Microbiology

Question 1

What is the most common cause of viral (aseptic) meningitis?

Answer 1

Enterovirus

Question 2

What are the dematiaceous molds?

Answer 2

Fast growers: Bipolaris, Drechslera, Exserohilum, Helminthosporum, Curvularia, Alternaria, Ulocladium and Stemphilium

Slow growers: Exophialia, Wangiella, Hortaea, Pseudoallescheria boydii/Scedosporium boydii complex and Scedosporium prolificans

Question 3

What is being shown here that is acquired from eating poorly cooked shellfish?

Answer 3

Paragonimus (lung fluke)

Question 4

What rapid growing mycobacterium:

• Negative iron uptake
• Tolerant to 5% NaCl (heavy growth)
• Negative nitrate reductase
• Resistant to all standard anti-TB drugs
• Fewer drug options than M. fortuitum
– Susceptible to amikacin, cefoxitin, imipenem,
clarithromycin
– Resistant to fluoroquinolones
• Clarithromycin is the drug of choice for localized
infections, although resistant strains are emerging

Answer 4

M. abscessus

Question 5

Explain how the different fermenters change the color of KIA/TSI slants initially and then at 24 hours (kind of a vague question but this is a paragraph in compendium and seems like good testable material).

Answer 5

Initially, a bacterium that ferments glucose but not lactose will produce an acidic (yellow) slant and acidic (yellow) butt. After the limited quantity of glucose is consumed, the organism will begin oxidative metabolism of proteins, which can only take place in the oxygen rich environment of the slant; this will turn the slant back to alkaline (red) by 24 hours, while the butt will remain yellow.

Therefore, when interpreting at 24 hours if the bottom is yellow and top is red, it means glucose fermenter only but if the top were yellow too it means lactose/sucrose fermenter in addition to glucose fermenter (both yellow, ferments both)

Question 6

What diseases and responsible organisms are transmitted by body lice (Pediculus humanus)?

Answer 6

• Epidemic typhus (Rickettsia prowazekii)
• Liceborne relapsing fever (Borrelia recurrentis)
• Trench fever (Bartonella quintana)

Question 7

What is the preferred lab test for Cryptococcus?

Answer 7

Latex antigen test

Question 8

What organism is seen in the photo?

Answer 8

Toxoplasma gondii

The latent form is represented by slow-growing protozoa forms called bradyzoites encased in cysts with a cyst wall. Multiple basophilic dot-like parasites can be seen in cysts

Question 9

What two mediums are mycobacterium spp grown in?

Answer 9

Lowenstein Jensen (solid medium egg based)

Middlebrook (agar based)

Question 10

What is the only malaria spp to have quartan fevers (every 72 hours instead of 48 hours)?

Answer 10

P malariae

Question 11

What parasitic organism is shown here and how can you be sure?

Answer 11

Entamoeba histolytica

Cannot distinguish E. histolytica/dispar unless RBCs seen in trophozoites

Erythrophagocytosis is diagnositc of histolytica cyst

Question 12

Which bacterial spp produces chalky white colonies which become salmon orange pink when they mature, have a “musty basement” odor, is lysozyme resistant and has aerial hyphae?

Answer 12

Nocardia spp

Question 13

What egg is this?

Answer 13

Taenia spp

Question 14

What are the ampC organisms resistant to that the ESBLs are not?

Answer 14

The cephamycins (cefoxitin and cefotetan)

AmpC is also resistant to the beta lactamase inhibitors

Question 15

Which virus causes this cytopathic effect?

Answer 15

HSV

RAPID (time to CPE 1-3 days), shrunken or enlarged cells starting at the edge of the cell sheet, sweeping CPE, occasional giant cells

Can be found in PMK and Hep2 (++) but grows best in HDF cells (+++)

*PMK=Primary Monkey Kidney, Hep2/HeLa=Human Epithelial Cells, HDF=Human Diploid Fibroblasts

Question 16

The organism seen here on this cornmeal plate looks similar to Candida glabrata (which will not have spaces between colonies) and it is UREASE positive and produces MELANIN on bird seed agar?

Answer 16

Cryptococcus neoformans

Urease positive and also phenol oxidase positive

Question 17

Which clostridium species is boxcar shaped and preliminary ID involves demonstrating lecithinase activity?

Answer 17

C. perfringens

*Double zone of beta hemolysis on blood agar

Question 18

Where is the latency and what are the acute and reactivation diseases caused by:

1) HHV6
2) HHV7
3) HHV8

Answer 18

1) HHV 6 is dorment in T cells and causes roseola (exanthem subitum) and can be reactivated in immunocomprised
2) HHV7 is dorment in lymphocytes and causes roseola (occasionally) and can be reactivated in immunocomprised
3) HHV8 is dorment in B lymphocytes and endothelial cells and causes unknown disease acutely but reactivation causes Kaposi sarcoma and Primary Body Cavity lymphoma

Question 19

Fulminant rocky mountain spotted fever can be seen in patients with what other disease?

Answer 19

Glucose-6-phosphatase deficiency

Question 20

What antibiotics are the enterococci intrinsically resistant to?

Answer 20

The enterococci are intrinsically resistant to cephalosporin antibiotics, clindamycin, trimethoprim-sulfamethoxazole, and the aminoglycosides (with the exception of high-level aminoglycoside resistance screening). In vitro susceptibility testing should not be performed on enterococci for these antimicrobial agents as these agents may appear effective in vitro but are not clinically effective.

Question 21

What two types of malaria DO recur from the liver?

Answer 21

– P. vivax – high incidence, most of the world except Western Africa

– P. ovale – lower incidence, occupies the niche in Western Africa

Question 22

What are the major causes of pneumonia in the setting of animal exposure from:

1) Cattle or cats
2) Birds
3) Bat or bird droppings, especially pigeons
4) Mouse urine and feces
5) Rabbits

Answer 22

1) Coxiella burnetii
2) Chlamydophila psittaci and Cryptococcus neoformans
3) Histoplasma capsulatum
4) Hantavirus
5) Francisella tularensis

Question 23

What organism is this?

Answer 23

Fusarium

Common in fungal keratitis (most commonly F. solani complex)

Macro and Microconidia

Question 24

Where in the US can Mycobacterium leprae be found?

Answer 24

Causes leprosy (Hansen disease)

In the US, found in Hawaii, Texas and Louisiana where it is harbored by armadillos.

Cannot be cultured on artificial media. In tissue biopsy, be visualized with Fite stain

Question 25

What is the 3 day test that rapid grower mycobacterium spp will be positive for?

Answer 25

Positive **_3 day arylsulfatase test_** –M. fortuitum complex (polymyxin B - S) –M. chelonae (polymyxin B – R; citrate negative, growth in 5% NaCl) – M. abscessus (polymyxin B – R; citrate positive, no growth in 5% NaCl)

Question 26

What HPV types cause anogenital squamous cell carcinoma? What is the caveat with verrucous carcinoma?

Answer 26

HPV 16 and 18 account for most cases Verrucous carcinoma (giant condyloma of Bushke and Lowenstein) is nearly always associated with HPV 6 or HPV 11

Question 27

Which Enterobacteriaceae are strong lactose fermenters?

Answer 27

E coli, Klebsiella, Enterobacter

Question 28

What two organisms are seen in intracellular vacuoles where they appear as mulberries or morulae and how you do tell them apart?

Answer 28

Ehrlichiosis and Anaplasma Human MONOCYTIC ehrlichiosis (HME) is caused by Ehrlichia chaffeensis Human GRANULOCYTIC anaplasmosis (HGA) is caused by Anaplasma phagocytophilum Therefore, the intracellular inclusions will look the same with both organisms and are told apart by the KIND of cell they are inside (monocyte=Ehrlichia, granulocytes=Anaplasma)

Question 29

Describe the mechanism and gene involved in MRSA

Answer 29

Based upon expression of altered penicillin binding proteins; these carry the mecA gene which allows them to express PBP2A, a penicillin target with little affinity for the drug. MRSA can be identified using routine disk diffusion testing with cefoxitin as the indicator drug, or with DNA hybridization probes to detect mecA or by detection of PBP2A using latex agglutination.

Question 30

What diseases and responsible organisms are transmitted by the Culex spp of mosquito?

Answer 30

- Arboviral disease including west nile virus, St Louis encephalitis virus, Japanese encephalitis virus - Lymphatic filariasis (Brugia malayi and Wuchereria bancrofti) \*Anopheles spp also transmits lymphatic filariasis

Question 31

What is Dr. Huber's mneumonic for remembering the AmpC Beta-lactamase producing organisms? \*AmpC organisms are resistant to beta-lactamase inhibitors--generally causes resistance to all beta-lactams, except carbapenems and 4th generation cephalosporins (cefepime)

Answer 31

"My SPACE" Morganella Serratia Proteus (not mirabilis), Providencia, Psuedomonas Aeromonas, Acinetobacter Citrobacter freundii (not kosari) Enterobacter

Question 32

What is the difference between a tube coagulase test and a slide coagulase test and which is the definitive one?

Answer 32

-Tube coagulase test detects FREE (secreted) coagulase and is the DEFINITIVE test--isolate is mixed with plasma in a tube and if coagulase is present will complex with coagulase reacting factor (CRF) in plasma which converts fibrinogen to fibrin forming a clot. Necessary to examine at 4 and 24 hours to avoid false negative. -Slide coagulase test detects cellbound coagulase (known as clumping factor). This test is faster but need tube test to confirm

Question 33

Interpret this KIA/TSI slant:

Answer 33

K/A (red/yellow) means alkaline slant over acid butt. The bottom was fermented and the top was not! If the bottom is yellow, it means glucose fermenter and if the top were yellow it means lactose/sucrose fermenter. This result means the bacteria is a glucose fermenter only. In addition, it is an H2S producer. Possibilities include: **Salmonella, Edwardsiella, Citrobacter (freundii), Proteus** "Black PECS"

Question 34

What organism is shown here?

Answer 34

Trypanosoma cruzi \*Brucei looks similar except it will not be C shaped and it can be seen dividing wheras Cruzi will not usually be seen dividing

Question 35

What HPV types (in order of frequency) cause oral focal epithelia hyperplasia (Heck disease)?

Answer 35

13, 32

Question 36

What types of HPV (in order of frequency) cause HSIL?

Answer 36

16, 18, 31, 33, 35

Question 37

This nematode is acquired from ingestion of raw or undercooked fish and biopsy may disclose an eosinophil rich granuloma containing the nematode.

Answer 37

Anasakiasis

Question 38

What parasite is shown here on this acid fast stain which is characterized by these smudgy blobs but if you are lucky you will see the 4 sporozoites (left)? Antigen detection is test of choice

Answer 38

Cryptosporidium ## Footnote - Resistant to **_chlorination_**, killed by ozonation, desiccation (2 h) - Organisms excyst in small intestine, enter brush border epithelial cells but remain extracytoplasmic VERY low infectious dose

Question 39

What two gene loci have been identified in isoniazid resistance in TB? What about rifampin, pyrazinamide and streptomycin resistance? *\*alot of info on 1 card but this was in OSLER lecture, seems important but I don't know how important so I just made a card*

Answer 39

– **katG**: a catalase/peroxidase, probably responsible for transforming INH to an active drug – **inhA**: involved in mycolic acid synthesis, probably a direct target of INH action Alterations in these 2 genes responsible for at least 85% of INH resistance **_Rifampin resistance_** – rpoB, the beta subunit of RNA polymerase alterations in this locus responsible for \>95% of RMP resistance **_Pyrazinamide resistance_** – pncA, pyrazinamidase, cleaves pyrazinamide to pyrazinoic acid – PZA inhibits a fatty acid synthetase; resistance mutations in this locus as well **_Streptomycin resistance_** – rpsL, S12 ribosomal protein – rrs, 16S ribosomal RNA

Question 40

What is a modified acid fast stain and name 4 organisms it is useful in IDing.

Answer 40

Decolorization with dilute sulfuric acid rather than 1M HCl Nocardia, Cryptosporidium, Cyclospora and Isospora

Question 41

What is the one haemophilus that does not require X or V Factor to grow (the only one that will grow by itself on blood agar)?

Answer 41

Haemophilus aphrophilus \*not really haemophilus anymore, moved to aggregatibacter Abscesses (liver, lung, brain) and endocarditis (the H in HACEK)

Question 42

In what patient population has an unusual inhalational form of Sporothrix been identified?

Answer 42

chronic alcoholics

Question 43

What organisms produce a green metallic sheen on EMB agar?

Answer 43

E coli and rarely Citrobacter freundii

Question 44

The optimal culture temperature for initial incubation is 37C. What are the caveats regarding: 1) Yersinia enterocolitica and certain Pseudomonas spp (P fluorescens, P putida) 2) Campylobacter jejuni and Campylobacter coli 3) Listeria monocytogenes

Answer 44

1) Grow optimally at 25-30C 2) Grow optimally at 42C 3) Grows optimally at 37C but displays its characteristic motility only at 25C and is notoriously able to multiply at refrigeration temperature (4C)

Question 45

What form of plasmodium spp is being shown here?

Answer 45

Band form of P. malariae Think of this one as the "gigolo" of the spp because it likes older red cells so they wil be SMALLER **Band form is pathognomonic!** **Mature form will have 8-12 merozoites rosetting with PIGMENT**

Question 46

Which antibiotics have almost universal coverage against the anaerobes?

Answer 46

Metronidazole, carbapenams and beta-lactam combos have almost universal coverage

Question 47

What is the general mechanism of action for ESBL?

Answer 47

ESBLs are TEM and SHV class beta lactamases that hydrolyze penicillins, cephalosporins and the monobactam, aztreonam, conferring resistance to all of these drug classes. ESBLs do not hydrolyze the cephamycin antibiotics (ie; cefoxitin and cefotetan). ESBL’s are also inhibited by beta-lactamase inhibitors such as clavulanate, sulbactam and tazobactam. \*LOOK FOR--decreased susceptibility to 3rd generation cephalosporins or aztreonam with MICs\>1mcg/mL and resistance to multiple cephalosporins but susceptibility to cephamycins (cefoxitin and cefotetan)

Question 48

Which two selective medias are used for cultivation and isolation hardy enteric gram negative rods?

Answer 48

- MAC (has bile salts and crystal violet which inhibit growth of gram positive bacteria and delicate gram negative bacteria) - EMB (eosin methylene blue which has aniline dyes that inhibit the growth of gram positive bacteria)

Question 49

1) Which Nocardia complex can cause indolent soft tissue infections in normal immunocompetent hosts? 2) Which Nocardia complex can cause invasive pulmonary infection and disseminated infection involving CNS in immunocompromised hosts?

Answer 49

1) Nocardia brasiliensis complex 2) Nocardia asteroides complex (includes N. asteroides, N. nova, N. abscessus and N. farcinica--particularly drug resistant)

Question 50

What is being shown here that is acquired by eating larvae with edible water plants?

Answer 50

Fasciola hepatica (liver fluke)/Fasciolopsis buski (intestinal fluke) Cannot tell eggs apart

Question 51

What disease and responsible organism is transmitted by the reduviid bug (Triatominae)?

Answer 51

American trypanosomiasis "Chagas disease" (Trypanosoma cruzi)

Question 52

Which rapid growing mycobacterium: * Positive iron uptake * Tolerant to 5% NaCl (heavy growth) * Positive nitrate reductase * Resistant to all standard anti-TB drugs

Answer 52

M. fortuitum group

Question 53

What yeast is presumptively ID'd using a rapid trehalose assimilation test?

Answer 53

Candida glabrata

Question 54

Which species is responsible for the majority of cases of aspergilloma and allergic bronchopulmonary aspergillosis?

Answer 54

A fumigatus

Question 55

1) What are the anaerobic spore forming gram positive bacilli? 2) What are the anaerobic non-spore forming gram positive bacilli? 3) What are the aerobic spore forming gram positive bacilli? 4) What are the aerobic non-spore forming gram positive bacilli?

Answer 55

1) Clostridium spp (perfringens, septicum, botulinum, tetani, difficile) 2) Actinomyces (same gram stain as Nocardia but Nocardia is aerobic and acid fast unlike Actinomyces), Propionibacterium 3) Bacillus spp (anthracis, cereus) 4) Listeria monocytogenes, Erysipelothrix rhusiopathiae, Nocardia, Rhodococcus equi, Corynebacterium diphtheria and Tropheryma whipplei

Question 56

What is the carriage rate for Neisseria meningitides and what is the site?

Answer 56

10%, oropharynx

Question 57

What is the significance of the lipopolysaccharide portion of the gram negative cell wall?

Answer 57

Endotoxin (Lipid A portion) O polysaccharides are used for serotyping

Question 58

Which dermatophyte produces a red pigment on the BACK of the plate and shows tear shaped microconidia arranged along the hyphae giving a "birds on a wire" appearance?

Answer 58

Trichophyton rubrum

Question 59

What biochemical test can be used to differentiate between the MTB complex species?

Answer 59

M. tuberculosis complex contains VERY closely related organisms which include M. bovis, BCG and M. africanum **Niacin/Nitrate can help!** **MTB is niacin/nitrate positive, M. bovis and africanum are negative** All produce a catalase that is labile at 68 degrees; most other mycobacteria produce heat-stable catalase!

Question 60

Which Enterobacteriaceae are hydrogen sulfide positive?

Answer 60

Salmonella, Edwardsiella, Citrobacter freundii, Proteus

Question 61

What is the carriage rate for strep pneumo in adults and in children and what is the site?

Answer 61

Adults-5%, Children-50% Oropharynx

Question 62

What does the Campy-BAP contain?

Answer 62

Antimicrobials to which Campylobacter spp are resistant (cephalothin, vancomycin, trimethoprim, amphotericin B and polymyxin B)

Question 63

What egg is this?

Answer 63

Trichuris trichiura (whipworm) Remember that the name is symmetrical and so is the egg with a lucent mucoid plus on each end

Question 64

What are the viruses that are NOT cultivatable with routine viral culture?

Answer 64

HIV-1; hepatitis C virus; hepatitis B virus; parvovirus B-19; human herpesviruses 6, 7, and 8; Epstein-Barr virus; human papillomavirus; BK virus; and JC virus

Question 65

What are the features of Legionnaires' disease?

Answer 65

Atypical pneumonia with high fever, **_hyponatremia_**, renal dysfunction, diarrhea and neurologic abnormalities

Question 66

Carbapenemases are grouped as molecular classes A, B and D. What organisms have: 1) Class A 2) Class B 3) Class D 4) What test illustrates KPC mediated resistance?

Answer 66

1) Predominately KPC which are found in Kleb pneumo, other Enterobacteriaceae and Serratia marcescens 2) Comprise the metallo-beta-lactamases such as IMP, VIM and SPM which are produced by Pseudomonas aeruginosa, Acinetobacter, Stenotrophomonas maltophilia and Enterbacteriaceae 3) OXA carbapenemase which are produced by Acinetobacter baumannii 4) Hodge test--Streak agar plate with carbapenam susceptible E. coli and put ertapenam disk in center and streak test organisms out from the disk. KPC organisms will distort zone of inhibition

Question 67

What parasitic infection can cause rectal prolapse?

Answer 67

Trichuris trichiura (whipworm)

Question 68

What are the metallo-beta-lactamases, what organisms have this and what antibiotic are these susceptible to that is different from the ESBLs and AmpC organisms?

Answer 68

VIM and IMP most common Require zinc for activity Pseudomonas and Acinetobacter (and a few enterics) Usually susceptible to aztreonam (but may be hidden by other enzymes)

Question 69

What is the most common helminthic infection in the world?

Answer 69

Ascaris lumbricoides

Question 70

What are the important thermally dimorphic fungi?

Answer 70

Histoplasma capsulatum Blastomyces dermatitidis Coccidioides immits/posadasii Paracoccidioides brasiliensis Sporothrix schenkii Penicillium marnefei

Question 71

What two antibiotics are Proteus spp intrinsically resistant to?

Answer 71

Tetracycline and nitrofurantoin

Question 72

What virus causes the inclusion shown?

Answer 72

Herpes Simplex Virus This picture is showing a Cowdry type A inclusion ("owl eye") bodies in multinucleated cells; nuclei are molded and chromatin in marginated

Question 73

DEFINITE BQ! ## Footnote Need to know how to recognize glucose fermentation in OF media (oxidation/fermentation) media. Which of these pairs of tubes is showing glucose fermentation?

Answer 73

Pair 3 ## Footnote First tube in each pair is open and the second in each pair is overlayed (closed) No yellow at all is negative reaction Yellow in open tube but not closed = oxidation only Yellow in both tubes = glucose fermentation

Question 74

What are 3 causes of false positive results with Cryptococcus antigen test?

Answer 74

– Trichosporon beigelii infection (cross-reactive polysaccharide is produced) – Contamination with agar and syneresis fluid on agar – Platinum wire loops

Question 75

What virus causes X linked lymphoproliferative disease (Duncan disease) and what is this disease?

Answer 75

EBV ## Footnote Fulminant primary EBV infection, frequently fatal. Affects mainly males and patients with this disorder mount an overactive immune response to EBV resulting in fulminant infectious mononucleosis, B cell lymphoma, aplastic anemia and dysgammaglobulinemia. Mechanism of death is usually hepatic necrosis; may be due to hemophagocytosis, agammaglobulinemia, B cell lymphoma ***Defect is found in the SH2DIA (SAP) gene*** Results in uncontrolled activation of T/NK cells following EBV infection

Question 76

The CDC has defined a positive HIV1 Western blot as?

Answer 76

Any two of the following bands: p24, gp41, gp120/160 \*p24 protein is the earliest detectable at 2-3 weeks

Question 77

With malarial infections, how are the following inherited red cell anomalies protective? a) Hgb S b) Duffy negative blood type c) G6PD Def d) hereditary ovalocytosis

Answer 77

a) protective against P falciparum b) protective againt P vivax c) protestive against all spp d) protective against cerebral malaria

Question 78

What is the treatment for carbapenamase producing organisms (Klebsiella, E. coli)?

Answer 78

At this time, there are a limited selection of treatment options for CRE infections. Clinicians have been forced to re-evaluate the use of agents, which have been historically rarely used due to efficacy and/or toxicity concerns, such as _polymyxins, fosfomycin, and aminoglycosides_

Question 79

BQ! Organism Associated with Butyric Acid Production in the Chromatographic Test:

Answer 79

Fusobacterium

Question 80

What serotypes of adenovirus are associated with: 1) respiratory illness 2) hemorhaggic cystitis 3) childhood gastroenteritis

Answer 80

1) serotypes 1-14 and 21 2) serotypes 11 and 21 3) serotypes 40 and 41

Question 81

The mold form of Paracoccidioides is identical to that of which other fungus?

Answer 81

Blastomyces ## Footnote Paracoccidioides has been called the "South American Blastomyces: because they look and behave very similarly

Question 82

Of the plasmodium species, which one is shown here and can be idenfied if this finding is seen on smear?

Answer 82

Plasmodium OVALE ## Footnote Most reliable diagnostic feature (albeit often difficult to find) to support the identification is a Schizont containing 6-14 merozoites clustered around the “dark pigment”. This was the only schizont seen on 5 thin smears and contains 7 very dark staining merozoites. Enumerating these merozoites is a very reliable method for determining P. vivax from P. ovale, as P. vivax Schizonts contain 12-24 merozoites.

Question 83

Which spp of mycobacterium is characterized by: ## Footnote Found in hot water systems—optimum growth temperature is 42°C. May take 6 weeks or longer to grow because 37°C incubation is not optimal. Causes chronic pulmonary disease in adults with underlying disease (e.g. COPD or bronchiectasis). Extrapulmonary infection seen only in immunocompromised. Slow growth, **_optimum growth at 42°C_** Long, thin, branching, acid-fast rods on smear from liquid culture (“atypical morphology”) Scotochromogenic and identified biochemically (**arylsulfatase pos)**

Answer 83

M. xenopi

Question 84

Tuberculosis can be caused by any of the M. tuberculosis complex which includes which organisms?

Answer 84

M. tuberculosis M. microti M. bovis M. africanum M. canetti

Question 85

What is the carriage rate for staph aureus and what site?

Answer 85

50%, nares

Question 86

What organism is being shown in this Fite stain?

Answer 86

M. leprae Acid fast organisms infiltrating a nerve

Question 87

What is the most common cause of abdominal TB?

Answer 87

Mycobacterium bovis

Question 88

What two types of malaria DON'T recur from the liver?

Answer 88

– **P. falciparum** – high incidence and severity ## Footnote \*so severe and you don't see anything in blood other then ring forms because if it matures over the ring form, it sticks to vessel walls like crazy so you do not see it in peripheral blood – **P. malariae** – lower incidence and severity Both worldwide in the tropics

Question 89

What two bacteria non glucose fermenting gram negative rods that are inherently resistant to carbapenams (treated with trimeth-sulfa)?

Answer 89

Stenotrophomonas maltophilia Burkholderia cepacia

Question 90

What should you avoid when performing a catalase test? What are the other important catalase positive pathogens other than Staph?

Answer 90

Avoid contaminating with blood agar since RBCs produce catalase ## Footnote _Other catalase positive pathogens_: Campylobacter spp, Listeria spp and Bacillus spp

Question 91

Which bacterial organism colony morphology is nonhemolytic with irregular borders (Medusa head colonies) that are tenacious and stand up when teased with a loop?

Answer 91

Bacillus anthracis \*This is one of the few NONMOTILE bacillus organisms

Question 92

What organism causes encephalitis characterized by bilateral hemorrhagic necrosis within the anterior temporal lobes and is associated with RBCs in the CSF?

Answer 92

Herpes Simplex Type 1 CSF: RBCs, very high protein and low glucose \*HSV2 can cause meningitis but not encephalitis. HSV1 lies dormant in the trigeminal ganglia and HSV2 lies dormant in sacral ganglia.

Question 93

What virus causes the effect shown?

Answer 93

Measles (Rubeola) This is a Warthin-Finkeldey giant cell which can have up to 50 or more nuclei! The inclusions are nuclear, cytoplasmic and syncytial

Question 94

What virus causes the inclusion shown?

Answer 94

CMV A nuclear AND cytoplasmic inclusion that produces "owl eye" appearance but they are not multinucleated like HSV

Question 95

What disease does this organism cause?

Answer 95

Scabies

Question 96

What is being shown in the picture and what infection is this characteristic of?

Answer 96

This is a fibrin ring granuloma commonly seen in the liver and bone marrow of patients with Q fever caused by Coxiella burnetii

Question 97

Which anaerobe is ALWAYS resistant to metronidazole?

Answer 97

Propionibacterium acnes

Question 98

Which bacteria traverse the bowel wall and entrench themselves within reticuloendothelial cells of the liver, spleen and gallbladder and what is this disease? The gallbladder then acts as a reservoir continually reinfecting the bowel leading to long term shedding.

Answer 98

Salmonella typhi and Salmonella paratyphi Typhoid fever

Question 99

What bacteria is gram invisible, requires L cysteine supplementation for in vitro culture, shows whitish colonies in 2-5 days on BCYE and ID can be confirmed by direct fluorescent antibody or latex aggluttination methods?

Answer 99

Legionella

Question 100

What is this?

Answer 100

Schistosoma hematobium

Question 101

What organism causes both granulomatous amebic encephalitis and amebic keratitis in contact lens wearers?

Answer 101

Acanthamoeba \*Balamuthia mandrillaris also causes GAE

Question 102

What are some key characteristics and toxin produced by the following diarrheagenic strains of E coli: 1) EHEC (enterohemorrhagic) 2) ETEC (enterotoxigenic) 3) EIEC (enteroinvasive) 4) EPEC (enteropathogenic) 5) EAggEC (enteroaggregative)

Answer 102

1) EHEC (enterohemorrhagic)--capable of producing Shiga toxin associated with HUS, esp O157:H7 2) ETEC (enterotoxigenic)--watery diarrhea, main cause of "traveler's diarrhea", produces choleralike toxin 3) EIEC (enteroinvasive)--causes dysentery similar to Shigella, produces Shigalike toxin (T3SS), like Shigella it is nonmotile and lactose nonfermenting 4) EPEC (enteropathogenic)--causes dysentery similar to Shigella, DOES NOT produce Shigalike toxin 5) EAggEC (enteroaggregative)--infant diarrhea in underdeveloped countries and refractory diarrhea in HIV pts

Question 103

VRE: What are the types of resistance and antibiotics affected by: 1) VanA gene 2) VanB gene 3) VanC gene

Answer 103

1) high level inducible resistance, vancomycin and televancin (Enterococcus faecium and faecalis) 2) high-to-moderate inducible resistance, vancomycin only (Enterococcus faecium and faecalis) 3) low level constitutive resistance, vancomycin only (Enterococcus casseliflavus and gallinarum--intrinsically resistant to vanc)

Question 104

What is the lab test for Aspergillus (not the IgE test for allergic bronchopulmonary aspergillosis)?

Answer 104

ELISA assay for the serum marker galactomannan and/or 1-3-beta-D-glucan

Question 105

What egg is this?

Answer 105

Ascaris lumbricoides \*this LUMBER as rough outer surface

Question 106

What aspergillus spp is associated with oxalosis (calcium oxalate tissue deposition)?

Answer 106

A. niger

Question 107

What two main diseases does HTLV virus cause?

Answer 107

HTLV1 infects CD4 T lymphocytes 1) Tropical spastic paraparesis (HTLV associated myelopathy) affects women 3:1, causes demyelinating lesions within the upper thoracic and lower cervical cord 2) Adult T cell leukemia/lymphoma Lifetime risk 5% in infected people before the age of 20yrs, incubation period of 20-30 years. Patients present with HSM, jaundice, wt loss and may feature **hypercalcemia, skin rash, high serum concentrations of free IL-2 receptor and pronounced sense of thirst**

Question 108

Detection of β-D-galactoaminidase activity identifies what spp of Candida?

Answer 108

Albicans

Question 109

Which drugs lack proven in vivo efficacy for infections with Enterococci?

Answer 109

Enterococci may appear susceptible to cephalosporins, clindamycin, trimethoprim-sulfamethoxazole, and aminoglycosides (except for high-level resistance screening) in vitro. However, these antimicrobials have no proven in vivo, clinical efficacy. Antimicrobial susceptibility reports should therefore not report these drugs as susceptible.

Question 110

What are the two exceptions for treating asymptomatic bacteriuria? What is the criteria for diagnosis?

Answer 110

_Exceptions_: pregnant women and patients undergoing urologic instrumentation ## Footnote _Criteria_: Asymptomatic women--two consecutive voided urines with isolation of the same species, \>10⁵ cfu/mL Asymptomatic men--single voided urine with isolation of a single species \>10⁵ cfu/mL Men or women--single catheterized specimen, single bacterial species \>10² cfu/mL

Question 111

What is a Jarisch-Herxheimer reaction?

Answer 111

A reaction to endotoxin-like products released by the death of harmful microorganisms within the body during antibiotic treatment. It is classically associated with penicillin treatment of syphilis. Duration in syphilis is normally only a few hours. The reaction is also seen in other diseases caused by spirochetes.

Question 112

What is the rapid urease test and what organisms does it help identify?

Answer 112

Proteus and H pylori (urease positive) Splitting (hydrolysis) of urea alkalinizes the medium leading to color change (pink or red) Many bacteria have urease activity but only a few can degrade it quickly (within 4 hours) and are designated "rapid urease positive" organisms Brucella is also rapid urease positive

Question 113

What biochemical test is pretty much the only difference between Klebsiella oxytoca and Klebsiella pneumoniae?

Answer 113

K. oxytoca is indole positive and K. pneumoniae is indole negative

Question 114

What are the viral cytopathic effects of Varicella Zoster Virus (VZV) and how does it differ from HSV?

Answer 114

VZV grows very poorly in culture and it takes about 14 days to grow whereas HSV is very rapid (1-3 days). The CPE is the same characterized by focal shrunken or enlarged cells, but advancing in a slow continuous manner. VZV will NOT grow in Hep2/HeLa cells (HSV will) but will grow in PMK and HDF cells. *\*PMK=Primary Monkey Kidney, Hep2/HeLa=Human Epithelial Cells, HDF=Human Diploid Fibroblasts*

Question 115

What are the IV Runyon groups and what are the organisms in them?

Answer 115

Classification for non-TB mycobacterium **_I Photochromogens_** Only produce pigment after exposure to light (**M. kansasii--often isoniazid resistant and M. marinum)** **Others: M. simiae, M. asiaticum, M. szulgai (22-24 degrees)** **_II Scotochromogens_** Always pigmented (**M. gordonae)--**called tap water chromogen because it is so commonly isolated and almost never pathogenic, report as contaminant, **M. xenopi, M. scrofulaceum M. flaviscens, M. szulgai (37 degrees)** **_III Nonchromogens_** No pigment (**M avium complex and TB complex)** **_IV Rapid growers_** **M. chelonae and fortuitum complexes**

Question 116

Name three methods for direct exam of fungal specimens.

Answer 116

Calcofluor white, KOH, Lactophenol cotton blue/KOH

Question 117

What is the most common cause of aseptic meningitis in the winter and spring?

Answer 117

Lymphocytic Choriomeningitis Virus (LCM)

Question 118

What is this?

Answer 118

Taenia saginata ## Footnote Eggs of T. saginata are not infectious, unlike T solium; thus cysticercosis (larval form of disease in humans) due to T saginata does not occur

Question 119

What supplementation does Francisella tularensis require to grow?

Answer 119

Sulfhydryl compounds (cysteine and cystine); can be isolated on routine media after extended incubation. Oxidase and urease negative, beta lactamase positive

Question 120

What is the purpose of using buffered charcoal yeast extract (BCYE) agar?

Answer 120

Recovery of Legionella spp Contains cysteine and iron supplementation which is necessary to support growth of Legionella. The activated charcoal helps bind and sequester growth inhibitors that may be present in the specimen

Question 121

What diseases and responsible organisms are transmitted by the Anopheles species of mosquito?

Answer 121

- Dog heartworm (Dirofilaria immitis) - Malaria (Plasmodium spp) - Lymphatic filariasis (Brugia malayi and Wuchereria bancrofti) \*Culex spp also transmits lymphatic filariasis

Question 122

What are the molecular pathogen specific targets for staph aureus and MRSA in multiplex PCR assay?

Answer 122

Staphylococcal protein A (spa), SCCmec, and mecA gene ## Footnote The spa gene is specific for staph aureus. SCCmec is the genetic element carrying mecA which is inserted by transposition into the orfX gene. The mecA gene encodes the protein conferring methicillin resistance which codes for the production of penicillin binding protein 2A (PBP2A) which acts as a beta lactam resistant transpeptide.

Question 123

If you see organisms in a macrophage, how can you tell apart Leishmania vs Histoplasma and which one is being shown in this picture?

Answer 123

**Leishmania** ## Footnote will show discrete organisms with nucleus and kinetoplast (PAS NEG) The picture here is showing Histoplasma which will show budding yeast but parent and bud are not within a discrete membrane (PAS POS)

Question 124

Which of the dimorphic fungi are associated with sclerosing mediastinitis?

Answer 124

Histoplasma

Question 125

What spp of plasmodium is shown here?

Answer 125

P. ovale Makes the red cells ovale Schuffner dots ARE seen

Question 126

What are the two primary diseases caused by EBV infection?

Answer 126

1) Infectious mononucleosis (mainly in adolescents and young adults) 2) X linked lymphoproliferative disease (Duncan disease) which mainly affects males. Patients with this disorder mount an overactive immune response to EBV resulting in fulminant infectious mononucleosis, B cell lymphoma, aplastic anemia and dysgammaglobulinemia

Question 127

Which bacterial organism's presumptive ID involves demonstration of the ability to reduce _potassium tellurite to metallic tellurite_? This organism's presumptive ID is also demonstrated by brown-black colonies surrounded by black halos on _Tinsdale agar_.

Answer 127

Corynebacterium diphtheriae ## Footnote **\*also must show toxigenicity! They have to be infected with a certain type of phage to produce a toxin so to test for the toxin there is a Elek test!**

Question 128

Name that microfilariae! (A-D)

Answer 128

**A) Wucheria bancrofti** ## Footnote Sheathed, nuclei stop short of end of tail **B) Brugia malayi** Sheathed, two small nuclei in tail **C) Onchocerca volvulus** Unsheathed, from skin, not blood (**if you seen unsheathed microfilariae in blood, it is probably Mansonella perstans!)** **D) Loa Loa** Sheathed, nuclei to continue to end of tail

Question 129

How many oil immersion fields but you examine on thick and thin smears when looking for malaria?

Answer 129

at least 100 oil immersion thick film fields or 300 thin film fields is required to acheive the reported sensitivity (5 parasites/uL)

Question 130

What are the 3rd generation cephalosporins?

Answer 130

Cefotaxime Ceftriaxone Ceftizoxime Ceftazidime

Question 131

This fungus has a yellow-green to olive colony and LIGHT reverse of the plate.

Answer 131

Aspergillus flavus

Question 132

What organism is this?

Answer 132

Trichinella spiralis \*if you see worms encysted in muscle, think about this organism

Question 133

Why is it important to distinguish between Candida albicans and dubliniensis?

Answer 133

They are morphologically identical and are both germ tube positive but dubliniensis is more likely to develop fluconazole resistance ## Footnote Distinguish by: – C. albicans growth at 45C – C. dubliniensis dark-green colonies on Chromagar – C. dubliniensis reduction of 2,3,5-triphenyltetrazolium chloride

Question 134

What is Ramsey Hunt syndrome and what causes it?

Answer 134

Reactivation of VZV in geniculate ganglion of the facial nerve Causes: otalgia, unilateral facial paresis, vertigo, hearing loss and tinnitus

Question 135

What is Bowenoid papulosis and what causes it?

Answer 135

Multiple small (2-3 mm) pearly papules in the genital region (penis, vulva, anus) that histologically resembles SCC in situ. Rarely progresses to invasive cancer. Caused by HPV 16 and/or 18

Question 136

What diseases and responsible organisms are transmitted by the sandfly (Phlebotomus and Lutzomyia spp)?

Answer 136

- Leishmaniasis (Leishmania spp) - Bartonellosis; Carrion disease (Bartonella bacilliformis) - Arboviral disease (Vesicular stomatitis virus, Toscana and Sicilian virus)

Question 137

What two parasitic infections are capable of person to person spread?

Answer 137

Enterobius vermicularis Hymenolepis nana

Question 138

By what mechanism does EBV cause primary infection?

Answer 138

Enteres body through pharyngeal or genital mucosa Infects B lymphocytes via the C3d receptor (CD21) CD8 T cells proliferate and are responsible for peripheral atypical lymphocytosis The site of EBV latency is in the B cells; EBV genome persists in episomal form

Question 139

In addition to Staphylococcus, what are the other catalase positive pathogens?

Answer 139

Campylobacter spp, Listeria spp, Bacillus spp

Question 140

What is the novobiocin susceptibility test used for?

Answer 140

Distinguish Staphylococcus saprophyticus (resistant) from other coagulase negative Staph (susceptible)

Question 141

What is the germ tube test?

Answer 141

Separate spp of Candida ## Footnote – Grow yeast in serum 2h – Separates C. albicans (+ germ tube) and other Candida species (no germ tube, instead budding hyphae) C. **albicans is generally fluconazole susceptible (\>95%)**whereas other Candida include species with a higher frequency of resistance. When Candida is grown in human or sheep serum at 37°C for 3 hours, they forms a germ tubes, which can be detected with a wet KOH films as filamentous outgrowth extending from yeast cells. It is positive for Candida albicans and Candida dubliniensis. Approximately 95 – 97% of Candida albicans isolated develop germ tubes when incubated in a proteinaceous media.

Question 142

What do you have to do in order to grow Malasessia furfur?

Answer 142

Put olive oil on the plate! They need lipid to grow

Question 143

Which Enterobacteriaceae are Voges-Proskauer (VP) positive?

Answer 143

Klebsiella, Enterobacter, Hafnia, Serratia, Pantoea

Question 144

Which anaerobic gram negative bacilli show brick red fluorescence when exposed to UV light and after several days of growth, the colonies appear brown black in natural light?

Answer 144

Porphyromonas/Prevotella

Question 145

What is Loffler syndrome?

Answer 145

When nematode (roundworm, hookworm) larvae penetrate mucosa, enter bloodstream and larvae is carried to lungs. May produce transient infiltrates with eosinophilia

Question 146

If you have a patient with diarrhea lasting more than two weeks, what test should you suggest?

Answer 146

Get Giardia/Cryptosporidium antigen test!

Question 147

What is aminoglycoside synergy testing and what genus of bacteria is this recommended for?

Answer 147

Enterococcus--for sterile sites, CLSI recommends synergy testing Susceptibility to high levels of gentamicin and/or streptomycin will predict synergistic activity with penicillin, ampicillin or vancomycin

Question 148

What particular two species of Staphylococcus produce false positive slide coagulase tests and why?

Answer 148

Staph lugdunensis and Staph schleiferi because they produce clumping factor but not free coagulase

Question 149

What organism is this (including species)?

Answer 149

Aspergillus fumigatus The phialides only cover the TOP whereas flavus goes ALL the way around (see pic)

Question 150

Which bacteria forms white cerebriform (molar tooth) colonies?

Answer 150

Actinomyces israelii

Question 151

What are the 3 most common causes of otitis media?

Answer 151

Strep pneumo, Haemophilus influenza, Moraxella catarhalis

Question 152

What is Pontiac fever?

Answer 152

Flulike illness caused by Legionella pneumophila but without the pneumonia

Question 153

What are the gamma hemolytic gram positive cocci and what are their characteristic properties?

Answer 153

--Most strains of enterococci (PYR+, bile esculin+, grows in presence of 6.5% NaCl) --Most strains of strep bovis (PYR-, bile esculin+) --Some strains of viridans strep (PYR-, bile esculin-)

Question 154

What organism is shown here? ## Footnote - Asymptomatic to invasive intestinal / extraintestinal - Fetid “pigpen” odor to breath reported

Answer 154

Balantidium coli ## Footnote -Stool O&P – large ciliate Cysts have macro and micro nucleus

Question 155

The only medically significant ciliate organism is:

Answer 155

Balantidium coli Cilia and characteristic kidney bean-shaped macronucleolus

Question 156

What is this?

Answer 156

Schistosoma mansoni

Question 157

What are the major causes of pneumonia in the setting of alcoholism?

Answer 157

Streptococcus pneumoniae, Klebsiella pneumoniae, anaerobes (aspiration), gram negative aerobic bacilli

Question 158

What organism is being shown here (kind of trick question)?

Answer 158

Mycobacterium! You can only tell because of the characteristic "ghost cells"--the organisms are not picking up stain but you see a space where they are

Question 159

What are the 2nd generation cephalosporins?

Answer 159

Cefuroxime Cefoxitin and cefotetan (cephamycin group)

Question 160

What is the most common form of bacterial enteritis in the US?

Answer 160

Campylobacter jejuni \*most commonly identified cause of Guillain-Barre syndrome and causes reactive arthropathy in persons with HLAB27

Question 161

Where are the following spp of Treponema found and what disease do they cause: 1) T pallidum subspecies pertenue 2) T pallidum subspecies endemicum 3) T carateum

Answer 161

1) Africa, Asia, South America; causes yaws which is a tropical infection of the skin, bones and joints. The disease begins with a round, hard swelling of the skin and center may break open and form an ulcer. After weeks to years, joints and bones may become painful, fatigue may develop, and new skin lesions may appear. 2) Africa, Asia, Middle East; causes endemic nonvenerial syphilis (Bejel) which usually begins in childhood as a small mucous patch, often on the interior of the mouth, followed by raised, eroding lesions on the limbs and trunk. Periostitis of the leg bones is commonly seen, and gummas of the nose and soft palate develop in later stages. 3) South America; pinta which produces a raised papule, which enlarges and becomes hyperkeratotic. Lesions are usually present in the exposed surface of arms and legs. Local lymph nodes might be enlarged. Three to 9 months later, further thickened and flat lesions (pintids) appear all over the body. These generally resolve, but a proportion of people with pinta will go on to develop late-stage disease.

Question 162

What is the preferred specimen to culture for mycobacterium in kids?

Answer 162

gastric washings (early morning after overnight fast)

Question 163

What are the major causes of pneumonia in the setting of sandstorm exposure?

Answer 163

Coccidioides immitis/posadasii

Question 164

What is the K1 beta lactamase and what organism produces it?

Answer 164

Klebsiella oxytoca produces a chromosomal beta-lactamase, the K1 enzyme. Hyperproduction of the K1 enzyme can occur by mutation. The K1 enzyme is predominantly a penicillinase that can also significantly hydrolyze aztreonam, cefuroxime and cetriaxone and has weak activitiy against cefotaxome or ceftazidime. \*Organisms producing K1 beta lactamases may give false positive ESBL confirmatory tests with automated testing systems.

Question 165

Name three methods for the acid fast stain.

Answer 165

Cell wall structure like gram + but have mycolic acids which repel crystal violet/iodine so these acid fast methods use heat and/or phenol to allow a fuchsin dye to penetrate the hydrophobic barrier and stain the mycolic acids in the cell wall ## Footnote - Auramine/rhodamine (HCl decolorization then potassium permanganate counterstain. AFB will fluoresce orange on black background. Can restain with Kinyoun or Ziehl-Neelson for confirmation) - Kinyoun cold (red carbol fuchsin with higher concentration of phenol than Ziehl Neelson and no heat then HCl decolorization then methylene blue counterstain. AFB are red on a blue background) - Ziehl Neelson hot (red carbol fuchsin dye containing phenol is heated to aid penetration of cell wall; strong acid, 3% HCl, is used for decolorization

Question 166

What is the Thayer-Martin medium used for?

Answer 166

Recovery of Neisseria species from non sterile sites Contains Neisseria resistant antibiotics (vancomycin, colistin, nystatin and SXT)

Question 167

What diseases and responsible organisms are transmitted by rat fleas?

Answer 167

- Plague (Yersinia pestis) - Murine typhus (Rickettsia typhus)

Question 168

What bacteria is a tiny curved (seagull shaped) gram negative rod that needs a microaerophilic environment and grows on selective media at 42C, is oxidase and catalase positive?

Answer 168

Campylobacter jejuni \*HIPPURATE HYDROLYSIS positivity is key to distinguishing C jejuni from other Campylobacter spp!

Question 169

Which anaerobic gram positive bacilli is boxcar shaped and preliminary ID involves demonstration of lecithinase?

Answer 169

Clostridium perfringens (double zone of beta hemolysis)

Question 170

What are the cytopathic effects and culture characteristics of Rhinovirus?

Answer 170

CPE are focal granular and swollen cells. Will NOT grow in Hep2/HeLa cells but grows very well in HDF cells (+++). Will occasionally grow in PMK cells (+). Compendium does not mention time to CPE *\*PMK=Primary Monkey Kidney, Hep2/HeLa=Human Epithelial Cells, HDF=Human Diploid Fibroblasts*

Question 171

What is an increasingly common nosocomial pathogen that causes ventilator associated pneumonia, bacteremia, wound infections, UTIs and meningitis and has been associated with outbreaks of bloodstream infections, osteomyelitis, and complicated skin and soft tissue infections in US military and civilian personnel who were wounded while serving in Iraq and Afghanistan?

Answer 171

Acinetobacter baumannii ## Footnote This is a nonfermenter, gram negative, nonmotile, oxidase negative coccobacillus whose natural habitat is water and soil. It's ability to survive environmental desiccation for weeks contributes to its nosocomial transmission. It is HIGHLY drug resistant (one of the AmpC organisms but has many other resistance mechanisms). Carbapenams are the best choice if strain is susceptible.

Question 172

What fungal organism is a major concern as an opportunistic infection in burn victims?

Answer 172

Fusarium

Question 173

What HPV types (in order of frequency) cause oral squamous papillomas, laryngeal papillomas, condyloma accuminatum (genital warts), and LSIL?

Answer 173

6, 11

Question 174

How long after admission do you NOT accept stool specimens for routine stool pathogens and O and P exam in inpatients?

Answer 174

3 days

Question 175

What organism is shown here? It is unique in that high titers of serum antibodies is BAD (ie people that form Abs have disseminated disease) and the dissapearance of the antibodies is a sign of effective therapy?

Answer 175

Coccidioidomycosis

Question 176

The dimorphic yeast form of Paracoccidioides is often confused histologically with the mold form of what other dimorphic fungus?

Answer 176

Histoplasma

Question 177

What are the 1st generation cephalosporins?

Answer 177

Cafazolin, Cephalothin

Question 178

What biochemical tests can help differentiate between Proteus mirabilis and Proteus vulgaris?

Answer 178

Both are urea positive. Proteus mirabilis is indole NEGATIVE and Proteus vulgaris is indole POSITIVE. Proteus mirabilis is also ornithine carboxulase positive. The proteus spp OTHER THAN MIRABILIS have AmpC so will be resistant to cephalosporins including cephamycins so need to use quinolones or bactrim for these UTIs

Question 179

What egg is being shown?

Answer 179

Hookworm (can't tell apart Necator from Ancylostoma) Lucent shell with early embryo inside

Question 180

Describe the CAMP test and what organisms is it used to identify?

Answer 180

Identifies group B strep and Listeria monocytogenes Both produce CAMP factor which enhances staphylococcal beta hemolysin Isolate is streaked at a perpendicular angle to a staph aureus streak. Arrowhead shaped enhancement of beta hemolysis at the junction of the two streaks is characteristic of strep agalactiae; rectangular enhancement is characteristic of Listeria spp

Question 181

Interpret this KIA/TSI slant:

Answer 181

K/A (red/yellow) means alkaline slant over acid butt. The bottom was fermented and the top was not! If the bottom is yellow, it means glucose fermenter and if the top were yellow it means lactose/sucrose fermenters. This result means the bacteria is a glucose fermenter only. Possibilites include: **Shigella, Serratia, Morganella, Providencia, Yersinia** "MY SPS"

Question 182

What is the most common cause of antibiotic associated diarrhea and which strain is more virulent?

Answer 182

Clostridium difficile B1/NAP1/027 strain is more virulent due to deletion of tcdC gene (a toxin A/B regulatory gene) so there is increased production of toxins A and B

Question 183

What is the caveat regarding serologic testing for Bordetella pertusis?

Answer 183

Caveat: Serology is uninterpretable in immunized or unimmunized patients \<11 years of age – These patients are cultured regardless of duration of symptoms – Serology is never sent on these patients

Question 184

This dimorphic fungi looks like this as yeast (cigar bodies) and produces a black colony in culture, what is it?

Answer 184

Sporothrix schenckii The slide culture will look like this (daisy shaped with threads connecting to conidiophore)

Question 185

What are the biochemical characteristics of Pasturella multocida and what is the mneumonic for remembering?

Answer 185

**"COIN"** ## Footnote **C**atalase, **O**rnithine, **I**ndole and **N**itrate positive. Pasturella are most commonly associated with normal flora of dog and cat’s mouths. Infections due to Pasturella are commonly soft tissue infections secondary to bite wounds. However, Pasturella can cause a variety of disease manifestations, such as blood stream infections, meningitis, peritonitis, endocarditis, and osteomyelitis. _It is important to keep Pasturella in mind when a small Gram-negative coccobacillus that does not grow on MacConkey agar is isolated in the laboratory._

Question 186

Which of the following organisms grows as a mold with a characteristic daisy head shaped conidia? ## Footnote a) Chrysosporium b) Blastomyces c) Sporothrix d) Paracoccidioides e) Scedosporium

Answer 186

**c) Sporothrix** ## Footnote All the other molds listed can produce "lollipop" conidia. Sprothrix however produces a very characteristic "daisy head" conidia that is not easily confused with Blastomyces

Question 187

What is the organism seen here?

Answer 187

Enterobius vermicularis Cross section shows characteristic lateral alae

Question 188

What HPV types (in order of frequency) cause plantar warts?

Answer 188

1, 2

Question 189

This fungus has a dark brown to black colony with a LIGHT reverse of the plate.

Answer 189

Aspergillus niger

Question 190

IMPORTANT! What is listeria monocytogenes resistant to?

Answer 190

Cephalosporin!

Question 191

What are the seven latent diseases caused by EBV?

Answer 191

1) Burkitt lymphoma ## Footnote Endemic, sporadic and immunodeficiency associated forms; nearly 100% of endemic BL in African kids and 25% of sporadic and immunodeficiency associated cases caused by EBV 2) Hodgkin lymphoma (50% of cases EBV related) 3) Primary effusion lymphoma (70% of cases EBV related, 100% of cases are HHV8 related) 4) Lymphomatoid granulomatosis (systemic angiodestructive lymphoproliferative disease) 5) Posttransplant lymphoproliferative disorder (PTLD) More than 95% are EBV positive 6) Oral hairy leukoplakia Caused by EBV with HIV infection however **_EBER is negative_** 7) Nasopharyngeal carcinoma Nearly 100% EBV positive in Chinese and Inuit populations; 75% EBV positive in US

Question 192

Which Haemophilus spp: 1) require BOTH X and V factor 2) require X factor only 3) require V factor only 4) show hemolysis

Answer 192

1) H influenzae, H haemolyticus, H aegyptius 2) H ducreyi \*only species to do this! Think how do you get ducreyi? It's an STD so it's X rated (requires X factor) 3) H parainfluenza, H parahaemolyticus, H pittmaniae and H. paraphrohaemolyticus \*to remember, if it parts with a "P", it only requires "V" 4) H haemolyticus, H parahaemolyticus, H aegyptius (these show beta hemolysis)

Question 193

What virus causes the inclusion shown?

Answer 193

Adenovirus This is showing the smudge cells (a nuclear inclusion) produced by adenovirus in a case of adenovirus pneumonia. \*They could show this type of inclusion in multiple different organs

Question 194

What organism causes visceral larva migrans and ocular larva migrans? They wander throughout various organs and produce syndromes of hypereosinophilia, hepatosplenomegaly and pneumonitis.

Answer 194

VLM: Toxocara canis (dog roundworm) OLM: Toxocara cati (cat roundworm)

Question 195

What bacteria requires nicotinic acid, cysteine, and methionine for growth but does NOT require X or V factor, grows in 2-4 days on Bordet-Gengou or Regan-Lowe media incubated 35C with supplemental CO2 and colonies are small smooth and shiny which has been likened to a drop of mercury?

Answer 195

Bordetella

Question 196

What is the mneumonic to remember partially acid-fast organisms?

Answer 196

"DRTNG" (aka "darting") for acid-FAST * *D**ietzia * *R**hodococcus * *T**sukamurella * *N**ocardia * *G**ordonia \*note Dietzia is recently controversial as it may not be partially acid fast but this is good mneumonic

Question 197

Interpret this KIA/TSI slant:

Answer 197

A/A (yellow/yellow) means acid slant over acid butt. If the bottom is yellow, it means glucose fermenter and if the top were yellow it means lactose/sucrose fermenter. This organism is fermenting BOTH glucose and lactose. Possibilites include: **E coli, Klebsiella, Enterobacter and Citrobacter (not freundii which is H2S pos)** "CEEK"

Question 198

What two organisms will grow on chocolate agar but not on blood agar?

Answer 198

Haemophilus influenza and Neisseria gonorrhoeae

Question 199

How to remember the hyaline molds: 1) ones that occur in clusters 2) ones that have branching chain conidia 3) ones that occur singly

Answer 199

1) "**GAF**" (a tool to grab things and hold together in cluster) **G**liocladium **A**cremonium **F**usarium 2) "looking through a **P**AY telescope to **S**EE a **P**EN hanging from branch" **P**enicillium **S**copulariopsis **P**aecilomyces 3) Scedosporium, Beauveria, Sepedonium, and Chrysosporium

Question 200

Which Enterobacteriaceae are phenyalanine deaminase (PAD) positive?

Answer 200

Proteus, Morganella, Providencia

Question 201

What are the major causes of pneumonia in the setting of AIDS?

Answer 201

Pneumocystis jiroveci, Cryptococcus neoformans

Question 202

Which Enterobacteriaceae are nonmotile?

Answer 202

Shigella Klebsiella Yersinia (nonmotile at 37C but motile at 22C)

Question 203

What disease is characterized by hyperplastic mucosa with pseudoepitheliomatous squamous hyperplasia, granulomatous inflammation, foamy macrophages and plasma cells with Russell bodies? What organism causes this? What is the characteristic cell called that is associated with this disease?

Answer 203

Rhinoscleroma, a chronic granulomatous disease of the upper airways caused by Klebsiella rhinoscleromatis. Produces foamy macrophages containing bacteria which are called MIKULICZ CELLS

Question 204

PREVIOUS BOARD Q! What two toxins are responsible for the double zone of beta hemolysis seen in Clostridium perfringens?

Answer 204

Beta hemolytic theta toxin, and alpha hemolytic alpha toxin

Question 205

What fungal organism causes a characteristic syndrome of lung infection PLUS skin involvement?

Answer 205

Blastomycosis (also paracoccidiodomycosis) Also causes penile and prostate disease in men \*just like when you see lung plus brain, think NOCARDIA

Question 206

What is the name of the structure shown and what is it associated with?

Answer 206

Sclerotic (muriform) bodies which are sclerotic bodes having internal septations in more than one plane Seen in chromoblastomycosis which is a subcutaneous mycosis assoiated with _promient pseudoepitheliomatosis hyperplasia_ Principle agents: *Fonsecaea pedrosoi, Phialophora verrucosa and Cladophialophora carrionii*

Question 207

Which form of Plasmodium is described as intraerythrocytic collections of numerous organisms?

Answer 207

Schizonts Multiple merozoites are inside one schizont

Question 208

What are the requirements for routine blood cultures?

Answer 208

- Blood cultures x 2 drawn sequentially - 20mL draws divided between aerobic and anaerobic bottles (40mL total which means 10mL per bottle) -No more than 3 in a 24 hour period - \*To r/o endocarditis draw a third BC 20-60 minutes after the first two (and repeat the following day if still negative) - Pedi draws can be less volume and single draw

Question 209

What diseases and responsible organisms are transmitted by the Lone Star tick (Amblyomma americanum)?

Answer 209

- Erlichiosis (Ehrlichia spp) - Tularemia (Francisella tularensis) - Southern tick associated illness (unknown etiology)

Question 210

What Corynebacterium is strongly associated with urinary tract infections associated with formation of struvite crystals and is usually multiple antibiotic resistant?

Answer 210

Corynebacterium urealyticum

Question 211

Which subspecies within the strep bovis group is associated with colonic malignancy?

Answer 211

Strep gallolyticus, subspecies gallolyticus

Question 212

What organism is shown here?

Answer 212

Banana form of P. falciparum (gametocyte) If you see this, it is diagnostic but usually you will see the ring forms with either 1 or 2 dots or Applique forms where the organism is plastered against the side of the red cell \*Falciparum is the "slut" of the plasmodiums because it will infect any and every red cell

Question 213

What disease and responsible organism is transmitted by the Tsetse fly (Glossina spp)?

Answer 213

African trypanosomiasis (Trypanosoma brucei)

Question 214

What organism causes hemorrhagic cystitis and what is the clinical scenario where this is commonly seen?

Answer 214

Adenovirus 11 and 21 Most often seen in bone marrow transplant recipients

Question 215

Isavuconazole has activity against which organisms?

Answer 215

Isavuconazole was recently FDA approved for the treatment of invasive **aspergillosis and mucormycosis**. This triazole is available as a water-soluble intravenous formula with excellent bioavailability and few reported side effects. Like most azoles, isavuconazole inhibits cytochrome P450 (CYP)-dependent 14α-lanosterol demethylation which is required for fungal cell membrane ergosterol synthesis. This drug has been shown to have **activity against yeasts including all Candida spp. and Cryptococcus spp**.. For **hyaline molds, there is good activity against Paecilomyces lilacinus and Scedosporium apiospermum**, **but not S. prolificans**. S. prolificans demonstrates resistance to most antifungal agents. Isavuconazole also has activity against many dematiaceous molds and dermatophytes.

Question 216

What organism causes the characteristic feature shown in the picture which can permit preliminary ID?

Answer 216

Mycobacterium tuberculosis \*Picture is showing CORDING

Question 217

What spp of Candida tends to develop Amphotericin B resistance?

Answer 217

Candida lusitaniae

Question 218

What are the alpha hemolytic gram positive cocci and what are their characteristic properties?

Answer 218

--Strep pneumo (optochin susceptible) --Most viridans strep (optochin resistant, PYR-, bile esculin-) --Some strains of strep bovis (optochin resistant, PYR-, bile esculin+) --Some strains of enterococci, especially E faecium strains (optochin resistant, PYR+, bile esculin+, grows in presence of 6.5% NaCl)

Question 219

What disease and responsible organism is transmitted by the dung fly (Musca sorbens)?

Answer 219

Trachoma (Chlamydia trachomatis)

Question 220

What HPV types (in order of frequency) cause the common wart?

Answer 220

2, 1, 4 | (HPV7 in handlers of fish and meat)

Question 221

What is this?

Answer 221

Taenia solium (Pork tapeworm--solium is a shorter word than saginata and pigs are smaller than cows) Also solium has less uterine branches than saginata

Question 222

What organism demonstrates temperature dependent tumbling motility in wet mounts (best at room temp, not well demonstrated at 37C), reveals umbrella shaped motility in semisolid agar, CAMP test shows a rectangular zone of enhanced hemolysis, and can grow at 4C (may contaminate refrigerated foods)?

Answer 222

Listeria monocytogenes

Question 223

There are 6 capsular groups of Neisseria meningitidis associated with invasive disease. What are they? Where are they found? Which does the quadrivalent vaccine target?

Answer 223

6 groups: A, B, C, W-135, X and Y ## Footnote Group A and less often Group X predominately cause epidemics in Central Africa (the "meningitis belt") wheras groups B, C and W-135 commonly cause disease in industrialized nations. The human nasopharynx is the only known reservoir. A quadrivalent vaccine targeting the polysaccharide capsular antigens of serogroups A, C, Y and W135 is recommended in the US for military recruits, freshmen in college, prisoners and lab workers. The current vaccine does not cover group B due to the poor immunogenicity of its capsule.

Question 224

If a patient has clear symptoms of bacterial pharyngitis but rapid strep test is negative but culture picks up the organism, what is this likely due to?

Answer 224

Strep dysgalactiae subspecies equisimilis ## Footnote Common cause of pharyngitis in teens and young adults. The rapid strep tests are specific for group A strep (pyogenes) so culture is required for diagnosis

Question 225

Regarding parasitic oculocutaneous infections: 1) what parasite adult worm causes disease? 2) what parasite larvae causes disease?

Answer 225

1) Loa loa 2) Onchocerca volvulus

Question 226

What new FDA approved test is available for malaria?

Answer 226

Binax NOW approved 2007 * Detects P. falciparum (HRP2) and common malarial antigen separately (falcipurum channel is much more sensitive than other channel for other malarias) * Microscopy detection limit is ~5-20 parasites/ul * Negative results must be confirmed by thick and thin smears

Question 227

Where do Plasmodium sporozoites proliferate?

Answer 227

Liver

Question 228

Which Enterobacteriaceae are strongly urease positive?

Answer 228

Proteus, Morganella, Providencia rettgeri

Question 229

What EBV driven/related is disease is NEGATIVE with EBER?

Answer 229

Oral hairy leukoplakia

Question 230

What fungi has pseudohyphal extensions that extend from one corner of the rectangular arthroconidia and resemble a hockey stick?

Answer 230

Geotrichum ## Footnote Urease negative

Question 231

What is the Thiosulfate-citrate-bile salts-sucrose (TCBS) agar used for?

Answer 231

Recovery of Vibrio spp It has bile salts which inhibit gram positives and an alkaline pH which inhibits most enterics but enhances growth of Vibrio \*sucrose fermenters will be yellow thus making differentiating between the sucrose fermenting Vibrios (Vibrio cholerae) and sucrose nonfermenting Vibrios

Question 232

What types of HPV (in order of frequency) cause cervical adenocarcinoma in situ and invasive cervical adenocarcinoma?

Answer 232

18, 16, 45

Question 233

What is the premise behind the IFN-gamma release assay?

Answer 233

T cells of persons infected with M tuberculosis release IFN-gamma in large quantities when stimulated in vitro to ESAT-6 and CFP-10; as good or superior to PPD tuberculin skin test.

Question 234

What organism found in stool is shown here?

Answer 234

Isospora belli -Eosinophilia often present (not for other coccidians, Cryptosporidum and Cyclospora) Auto-fluorescence or modified acid fast stain

Question 235

A syndrome associated with recurrent Herpes encephalitis is called?

Answer 235

Mollaret's syndrome –Thought to be caused by Herpes Simplex or Varicella-Zoster virus –Acyclovir treatment

Question 236

What are the components of a gram stain?

Answer 236

Crystal violet, grams iodine, alcohol or acid alcohol and saffranin

Question 237

What bacterial organism that causes nongonococcal urethritis classically produces "fried egg" colonies?

Answer 237

Mycoplasma hominis

Question 238

What is the organism shown in this picture? ## Footnote - Questionable clinical significance – can find in almost every stool - Report when in significant numbers

Answer 238

Blastocystis hominis

Question 239

What is the beta glucuronidase enzyme activity test?

Answer 239

For presumptive ID of E coli A fluorometric substrate (MUG) can be employed which produces a compound that fluoresces under UV light and can be added to culture media like MacConkey which makes the medium differential for beta glucuronidase activity CAVEAT: the enterohemorrhagic strain of E coli associated with HUS (serotype 0157:H7) is MUG negative with is odd for E coli! It also does not ferment sorbitol in sorbitol MacConkey plates so sorbitol negative colonies of E coli are usually subbed to MAC/MUG plates and if they are neg, you have a presumptive ID of 0157H7 E coli!

Question 240

What is the carriage rate for C Diff in healthy infants, healthy adults and adults in long term care facilities?

Answer 240

Healthy infants-30%, Healthy adults-\<3% and adults in long term care-4-20%

Question 241

What plasmodium spp is shown here and how can you tell?

Answer 241

Schuffner dots of P. vivax Vivax is the "dirty old man" of the plasmodium spp because it likes young red cells Red cells are ENLARGED When they mature, they shown 12-20 merozoites so that is very helpful in distinguishing it from P. malariae

Question 242

BQ! Best stain to use for sulfur granules?

Answer 242

GRAM, GMS, or GIEMSA!

Question 243

This fungus has cinnamon brown colonies on the surface with a YELLOW or ORANGE reverse of the plate.

Answer 243

Aspergillus tereus

Question 244

What are the testing options for C difficile?

Answer 244

Culture in selective medium, cycloserine cefoxitin egg yolk fructose agar (CCFA), under strict anaerobic conditions. Colonies on CCFA are yellow with a ground glass appearance and fluoresce when exposed to UV light. Cultured C diff produces "horse manure" odor. Cytotoxic culture is the gold standard test for detecting toxin production (outdated). Molecular tests more common, can detect toxin A and toxin B genes. ELISA for stool toxin relatively insensitive. ELISA for stool glutamate dehydrogenase (GDH), an antigen produced by C diff, somewhat more sensitive than toxin ELISA.

Question 245

What virus emerged in the "4 corners" region of New Mexico, the deer mouse sheds virus in urine and feces and it causes a prodrome followed by ARDS? Peripheral blood findings include: thrombocytopenia, neutrophilia without toxic granulation, erythrocytosis and immunoblastic lymphocytosis

Answer 245

Hantavirus pumonary syndrome aka Sin Nombre virus

Question 246

What dimorphic fungi seen here produces this characteristic colony with diffuseable orange pigment?

Answer 246

Penicillium marneffii

Question 247

What virus causes the effect shown?

Answer 247

Rabies This is showing a Negri body (cytoplasmic inclusion) within a neuron

Question 248

What sequelae is responsible for most of the mortality from influenza virus?

Answer 248

Secondary bacterial infection (usually pneumonia)

Question 249

BQ! What is Vincent's angina?

Answer 249

**_Acute necrotizing infection of the pharynx caused by a combination of fusiform bacilli (Fusobacterium - a Gram negative bacillus) and spirochetes (Borrelia vincentii)_**. These are the same organisms that cause a gingivostomatitis known as trench mouth. These organisms are part of the normal oral flora. The patient complains of unilateral sore throat that increases in intensity over several days with an associated referred earache on the same side. In addition, the patient complains of a bad taste in the mouth and a fetid bad breath. On examination, there is a deep well circumscribed unilateral ulcer of one tonsil. The base of the ulcer is gray and bleeds easily when scraped with a swab. There may also be an associated submandibular lymphadenopathy. Vincent angina is diagnosed using a gentian violet-stained smear of the pharyngeal exudate, which demonstrates the presence of Fusobacterium and spirochetes. Penicillin or Clindamycin and surgical debridement are the recommended treatment.

Question 250

How long can a specimen remain at room temperature and still give reliable results?

Answer 250

General rule of thumb is two hours

Question 251

What strain of C diff is increasingly associated with severe C diff colitis?

Answer 251

BI/NAP1/027 strain Newest PCR assays can detect, in addition to toxin producing strains of C diff, 027 strains by detecting the toxin genes and the mutated form of the tcdC gene that typifies the 027 strain.

Question 252

Weird fact: What fungus can cause fungemia in pts on hyperalimentation (high lipids)?

Answer 252

Malassezia

Question 253

Which virus causes this cytopathic effect?

Answer 253

Adenovirus ## Footnote Grapelike clusters on Hep2! Time to CPE: 2-7 days *\*PMK=Primary Monkey Kidney, Hep2/HeLa=Human Epithelial Cells, HDF=Human Diploid Fibroblasts*

Question 254

What is the carriage rate for group B strep in pregnant women and what site?

Answer 254

10-30%, rectum/vagina

Question 255

What are culture negative UTIs often due to (name 3)?

Answer 255

Ureaplasma urealyticum, Chlamydia species or Mycoplasma hominis

Question 256

What is the oxidase test used for and what are the oxidase positive and negative organisms?

Answer 256

Initial classification of gram negative organisms _Oxidase positive_: Neisseria, Moraxella, Pseudomonas, Legionella and the curved gram negative rods (Campylobacter, Vibrio and Helicobacter) _Oxidase negative_: Enterobacteriaceae The reagent, P phenylenediamine, is oxidized by cytochrome oxidase forming iodophenol blue

Question 257

What organism is shown?

Answer 257

Trypanosoma Cruzi and Brucei (African sleeping sickness) look the same but if you see a dividing form (pic) it's NOT cruzi

Question 258

1) Which Vibrio species is sucrose positive on selective TCBS agar (yellow colonies) as well as string test positive? 2) Which Vibrio species is sucrose negative on TCBS agar (green colonies)?

Answer 258

1) Vibrio cholerae 2) Vibrio parahemolyticus

Question 259

What diseases and responsible organisms are transmitted by the Dermacentor spp of tick? \*Most common in southern and western US is Dermacentor andersoni, and in southern and eastern US is Dermacentor variabilis

Answer 259

- Rocky Mountain Spotted Fever (Rickettsia rickettsia) - Tularemia (Francisella tularensis) - Colorado tick fever (Colorado tick fever virus)

Question 260

If you see worms moving on agar plate with bacteria, what should you think about?

Answer 260

Strongyloides stercoralis ## Footnote **Autoinfection is unqiue to this worm!** This is the only one of the infective nematodes that is capable of replicating and produces more worms (with other you only have as many worms as you ingested eggs) Strongy is infected organs as they go and cause chronic eosinophilia which makes people with **HTLV**, on steroids and neutropenic susceptible to hyperinfection

Question 261

There is a serologic cell surface antigen test for Aspergillosis, Galactomannan test. What patient population can be a false positive for this test?

Answer 261

People that are taking Zosyn

Question 262

What are the main anaerobic gram positive cocci?

Answer 262

Peptostreptococcus, Finegoldia, Peptococus, Parvimonas, Anaerococus

Question 263

What does CIN agar contain and what is it used for?

Answer 263

Cefsulodin-Irgasan-Novobiocin and is used for recovery of Yersinia spp Mannitol fermenters will have a characteristics "bull's eye" colony (colorless with red center) which helps differentiate between mannitol fermenting Yersinia spp (ie Yersinia enterocolitica) and mannitol nonfermenting Yersinia spp

Question 264

What is the most common cause of eumycotic mycetoma in the US?

Answer 264

Scedosporium

Question 265

What are the beta hemolytic gram positive cocci and what are their characteristic properties?

Answer 265

--Strep pyogenes (PYR+, bacitracin susceptible, expresses Lancefield group A antigens) --Strep dysgalactiae (PYR-, bacitracin resistant, expresses Lancefield group C or G antigens) --Strep agalactiae (PYR-, bacitracin resistant, CAMP factor +, hippurate hydrolysis +, expresses Lancefield group B antigens) --Some strains of enterococci (PYR+, bile esculin+, bacitracin resistant, expresses Lancefield group D antigens) --Some strains of anginosus group Strep "strep milleri" (PYR-, bacitracin resistant, small colonies, butterscotch odor, may express Lancefield group A, C, F or G antigens)

Question 266

Name the causative organism: Hallmark feature is fever with lymphadenopathy, hepatosplenomegaly and malodorous perspiration; may be a cause of spontaneous abortion, hepatitis (with granulomas in biopsies) and endocarditis (a principal source of mortality)

Answer 266

Brucella ## Footnote This is a chronic granulomatous zoonotic infection transmitted to humans through infected animals. _Serologic tests to detect antibodies specific for Brucella are diagnostic_. This is one of the most common infections that can be acquired in microbiology labs from routine workup outside safety cabinets. Brucella exposed people that are classified as high risk are advised to receive postexposure prophylaxis with a regimen of doxycycline and rifampin for 21 days. The 2012 CDC guidelines for frequency of serologic testing on all workers exposed include a baseline at 6, 12, 18 and 24 weeks.

Question 267

Why can't Haemophilus spp grow on MacConkey or sheep blood agar?

Answer 267

Requires X and/or V factor X=hemin, V=NAD+ Sheep blood agar has an enzyme that neutralizes X and V factors but horse or rabbit blood agar doesn't so it will grow on those Can get small colonies on chocolate agar because this is a cooked agar and hemolysis releases the X and V factors

Question 268

Which rapid growing mycobacterium: • Negative iron uptake • Not tolerant to 5% NaCl (minimal growth) • Negative nitrate reductase • Resistant to all standard anti-TB drugs • Fewer drug options than M. fortuitum – Susceptible to amikacin, imipenem, tobramycin, clarithromycin – Resistant to fluoroquinolones, cefoxitin • Clarithromycin is the drug of choice for localized infections

Answer 268

M chelonae

Question 269

What bacteria shows puffball or cottonball colonies in serum supplemented thioglycolate broth, gram stain shows tangles of gram variable filamentous rods with moniliform swellings and is the causative agent of rat bite fever?

Answer 269

Streptobacillus moniliformis

Question 270

What are the major causes of pneumonia in the setting of a ventilated patient?

Answer 270

Staph aureus, Strep pneumoniae, Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia spp, Enterobacter spp, E coli and fungi

Question 271

Interpret this KIA/TSI slant:

Answer 271

(K/K) Red over Red means Alkaline slant over Alkaline butt so nothing was fermented This excludes all enterobacteriaceae as all are glucose fermenters. Possibilites include nonfermentative bacteria such as Pseudomonas, Eikenella, Moraxella, and Campylobacter.

Question 272

Which virus causes this cytopathic effect?

Answer 272

CMV ## Footnote Slow, focal clusters of CPE (plaques) on HDF ONLY! Time to CPE: 14 days *\*PMK=Primary Monkey Kidney, Hep2/HeLa=Human Epithelial Cells, HDF=Human Diploid Fibroblasts*

Question 273

What organism is the most common cause of onychomycosis?

Answer 273

Trichophyton rubrum

Question 274

DEFINITE BQ! What organism is shown here which has been grown at 30C and shows fluffy mold with TUBERCULATED MACROCONIDIA (spiny large spores)?

Answer 274

HISTOPLASMA Testing: serum antibodies (CF or ID to H or M antigens) or **_immunoassay for antigens**_ _**in urine, serum, CSF_** At 37C will show narrow based budding (picture)

Question 275

What are the serology findings at different stages of EBV infection?

Answer 275

_Early acute_: heterophile pos, IgM anti VCA pos, IgG anti VCAagG pos _Acute_: add IgG anti EA and anti EBNA _Convalescent_: heterophile and IgM go away, left with IgG anti EA, IgG anti VCAAgG and anti EBNA _Remote_: may loser IgG anti VCAAgG and left with anti EBNA and IgG anti EA

Question 276

What are the cytopathic effects and culture characteristics of influenza, mumps and parainfluenza? If there is no CPE, what test can you do to confirm?

Answer 276

Will either show no CPE or focally enlarged and granular cells; parainfluenza may have focal multinucleated giant cells. If minimal to no CPE, _CONFIRM WITH HEMADSORPTION/HEMAGGLUTINATION_ Time to CPE: 2-5 for influenza, and 3-10 days for mumps and parinfluenza. Grows best in PMK (+++) and may or may not grow in Hep2/HeLa and HDF cells. *\*PMK=Primary Monkey Kidney, Hep2/HeLa=Human Epithelial Cells, HDF=Human Diploid Fibroblasts*

Question 277

What HPV types (in order of frequency) cause epidermodysplasia verruciformis and what is this disease?

Answer 277

2, 3, 10, 5, 8 ## Footnote Also called Lewandowsky-Lutz dysplasia, colloquially known as tree man illness is an extremely rare autosomal recessive skin disorder associated with a high risk of carcinoma of the skin. It is characterized by abnormal susceptibility to HPVs of the skin.

Question 278

What disease and responsible organism is transmitted by the Ornithodoros spp of tick (soft ticks)?

Answer 278

Relapsing fever (Borrelia spp)

Question 279

What bacteria causes pharyngitis in OLDER childern and is beta hemolytic and catalase negative (must be ## Footnote distinguished from S. pyogenes in throat specimens) and to ID – **_reverse CAMP test_**?

Answer 279

Arcanobacterium haemolyticum

Question 280

Dual infections involving parasites: 1) Ascaris lumbricoides and \_\_\_\_ 2) Enterobius vermicularis and \_\_\_\_ 3) Babesia, Borrellia burgdorferi and \_\_\_ 4) Lepromatous leprosy or HTLV and \_\_\_\_

Answer 280

1) Trichuris trichiura 2) Dientamoeba fragilis 3) Anaplasma phagocytophilum 4) Strongyloides stercoralis hyperinfection

Question 281

Definite board Q! Be able to differentiate colonies of Staph from colonies of C. diphtheriae on tellurite agar. Which is this?

Answer 281

Staph! They will have a clear zone around them from lecithinase production Here is what C. Diphtheriae looks like

Question 282

If you are given a stem regarding someone being stung by a catfish barb, what main organism should you think about?

Answer 282

Edwardsiella tarda ## Footnote Edwardsiella is a member of the Enterobacteriaceae. It is typically associated with aquatic environments and animals that inhabit water. E. tarda can cause diarrhea in humans but is also a rare cause of extraintestinal infections, such as soft tissue infections. Systemic infection occurs most frequently in patients with liver disease or iron overload. E. tarda produce H2S, and are oxidase and urease negative and indole positive. Isolates are positive for lysine decarboxylase and ornithine decarboxylase.

Question 283

What disease and responsible organism is transmitted by mites (Liponyssoides sanguineus)?

Answer 283

Rickettsial pox (Rickettsia akari)

Question 284

This fast growing dematiaceous mold has oval transversely septated conidia that arise from bent conidiophores and they have germ tubes from both ends of the conidia in saline mounts incubated for 12-24 hours.

Answer 284

Bipolaris

Question 285

What disease can be seen in infected live born neonates as a result of Listeria monocytogenes infection?

Answer 285

Granulomatosis infantseptica --pyogenic granulomas distributed over the whole body and may suffer from physical retardation

Question 286

What organism is shown here which shows broad, aseptate hyphae, branching at 90 degree in tissue?

Answer 286

Mucormycetes (Rizopus, Mucor, Absidia)

Question 287

What organism is usually responsible for intestinal spirochetosis in humans?

Answer 287

Brachyspira aalborgi

Question 288

What diseases and responsible organisms are transmitted by the deer fly (Chrysops spp)?

Answer 288

- Tularemia "deerfly fever" (Francisella tularensis) - Loiasis (Loa loa)

Question 289

What are the probes used in the sequencing of mycobacterium spp?

Answer 289

**16S rRNA, hsp65, rpoB** ## Footnote Microseq system is FDA-approved for 16S. No single target is sufficient to identify all mycobacteria to the species level. Expensive, labor-intensive, but likely to expand as methods improve.

Question 290

These 3 dematiaceous slow growing molds have early yeast like growth (seen here) and late grow is mold like.

Answer 290

Exophiala, Wangiella, Hortaea (mold seen here) _Slow growing dematiaceous molds that are moldlike early and late_: Pseudoallescheria boydii/Scedosporium boydii complex and Scedosporium prolificans

Question 291

What is the mneumonic for remembering the organisms that are INTRINSICALLY resistant to vancomycin?

Answer 291

"PWEELL" Pediococcus, Weisella, Erysipelothrix, Enterococcus (casseliflavus and gallinarum), Leuconostoc, and Lactobacillus It is important to note that among the Lactobacillus genus, the resistance to vancomycin is seemingly species-specific. The species with the best-described resistance to vancomycin is L. rhamnosus. Weissella confusa was formerly grouped with the Leuconostoc genus and includes the former Lactobacillus confusus, which was also characterized by its resistance to vancomycin. Enterococcus faecium and faecalis can be resistant to vancomycin, however the resistance is acquired through plasmid encoded vanA or vanB genes, not intrinsic to the genome like E. casseliflavus and E. gallinarum which contain the vanC gene to mediate resistance in all isolates.

Question 292

What spp of Candida is INHERENTLY resistant to fluconazole but typically susceptible to voriconazole and posaconazole? What spp is resistant to amphotericin?

Answer 292

Candida krusei ## Footnote C. lusitaniae is considered resistant to amphotericin (despite low MICs in many cases)

Question 293

What species of enterococcus expresses altered penicillin binding proteins with little affinity for penicillins and are frankly resistant to penicillin, the aminopenicillins (ampicillin) and the carbapenams?

Answer 293

E faecium

Question 294

What strain of Shigella causes shigellosis in 1) the US and 2) in underdeveloped countries?

Answer 294

1) In the US, Shigella sonnei 2) In underdeveloped countries, Shigella flexneri (this species can lead to postinfectious arthritis in HLA-B27+ patients) Requires the smallest inoculum of any form of bacterial gastroenteritis--only 100-200 organisms Shigella dysenteriae can cause HUS

Question 295

What are the 4th and 5th generation cephalosporins?

Answer 295

4th: Cefepime 5th: Ceftaroline

Question 296

What parasitic organism is shown on this acid fast stain? If you stain 4 cysts, usually only a couple will pick up the stain so you will see some refractile, some staining. These also AUTOFLUORESCE blue in UV light

Answer 296

Cyclospora Kind of looks like crinkled paper inside Not picked up with Giardia/Cryptosporidium antigen test

Question 297

What is the characteristic lesion of yellow fever in the liver?

Answer 297

Extensive midzonal necrosis, Councilman bodies (eosinophilic structure in pic), microvesicular fatty metatmorphosis and ABSENCE of an inflammatory component

Question 298

This fungus has a blue-green colony with distinct white apron and a LIGHT reverse of the plate.

Answer 298

Aspergillus fumigatus

Question 299

What mycobacterium spp need to be cultured at 30 degrees?

Answer 299

M. marinum, M. hemophilum and M. ulcerans ## Footnote Skin specimens get processed in duplicate (one set at 35-37°, one set at 28-30°C) M. hemophilum requires hemin to grow

Question 300

What are the main causes of noninflammatory (watery without fever) infectious diarrhea and which is most common cause?

Answer 300

MOST COMMON cause of traveler's diarrhea: Enterotoxigenic E. coli (ETEC)--has heat labile (LT) and heat stabile (ST) enterotoxins Also: Vibrio cholera (serogroup O1 and O139), Clostridium perfringens, Staph aureus and Bacillus cereus

Question 301

Describe the PYR test and what does it help identify?

Answer 301

Identifies group A pyogenic strep and Enterococcus spp Both can enzymatically hydrolyze PYR yielding beta naphthylamide in presence of detection reagent yields red color change

Question 302

This slow growing dematicaceous mold has gray or black surface and reverse, its growth is inhibited by cyclohexamide, it has no sexual state and it's resistant not only to ampho B but also to the azoles and echinocandins making antifungal therapy ineffective.

Answer 302

Scedosporium prolificans

Question 303

What is a Buruli ulcer and what organism causes it?

Answer 303

Indolent, necrotizing ulcerating cutaneous lesions caused by Mycobacterium ulcerans

Question 304

What test is used to predict response to interferon/ribavirin therapy in genotype I HCV?

Answer 304

IL 28B Mutation

Question 305

What is the Regan-Lowe medium used for?

Answer 305

Recovery of Bordetella pertussis and Bordetella parapertussis Contains cephalexin to which Bordetella is resistant

Question 306

Which method is most commonly used in molecular epidemiology to generate strain specific molecular fingerprints to determine microbial strain relatedness in a hospital setting?

Answer 306

Pulsed-field gel electrophoresis (PFGE) ## Footnote Molecular strain typing methods in a hospital setting are most often applied to determine whether a cluster of infections in a particular medical unit is caused by a single clone or multiple strains. PFGE is the gold standard and involves generating large DNA fragments (40kb to 2000 kb) by restriction endonuclease digestion of chromosomal DNA with agarose plugs. Plugs are added to agarose gel and pulsed electric fields separate fragments into distinct patterns.

Question 307

What organism causes the characteristic finding of a widened mediastinum noted on anterior posterior plain films of the thorax caused by hemorrhagic mediastinitis?

Answer 307

Bacillus anthracis

Question 308

Describe what a Kligler iron agar and triple sugar iron (KIA/TSI) slant is.

Answer 308

Agar slants that contain proteins, sugars and a phenol red indicator. There is a 10:1 ratio of lactose:glucose for KIA or 10:1 lactose:sucrose and glucose for TSI. Phenol red indicator is yellow when pH is 6.8. Fermentation is evidenced by lowering the pH (yellowing of the indicator). The tubes are interpreted at 24 hours. When interpreting, "K" means alkaline and "A" means acid (ie K/A means alkaline slant over acid butt)

Question 309

The mycobacterium avium complex includes both Mycobacterium avium and Mycobacterium intracellulare and infection can be seen in both immunocompetent and immunosuppressed patients. Amongst immunocompetent, there are 3 forms of disease, what are they?

Answer 309

1) Seen in heavy smokers with upper lobe cavitary disease resembling classic TB 2) "Lady Windermere syndrome" seen typically in elderly women with a weak cough; akin to colonization 3) Hypersensitivity reaction to MAC after exposure to hot tub water contaminated with the organism \*MAC is the most common cause of scrofula in US!

Question 310

What is the spirochete shown (tight coils with hooked ends) and what disease does it cases?

Answer 310

Leptospira interrogans Causes Weil disease which has classic triad of meningitis, hepatitis and nephritis. Humans are infected through contact with the urine of an infected animal, the usual portal of entry being the conjunctiva or abasions/cuts in skin. In US, highest incidence in Hawaii and rats are usual hosts

Question 311

What fungi causes eumycotic mycetoma after penetrating trauma, fungal keratitis, and _pneumonia after near drowning incidents_ (weird fact so probably good for boards)?

Answer 311

Pseudallescheria boydii/Scedosporium boydii ## Footnote **Both are resistant to Ampho B**

Question 312

What HPV types (in order of frequency) cause flat (juvenile) warts?

Answer 312

3, 10

Question 313

What diseases and responsible organisms are transmitted by the Ixodes spp of tick? \*Most common Eastern US is Ixodes scapularis, in Western US is Ixodes pacificus and in Europe is Ixodes ricinus

Answer 313

- Lyme disease (Borrelia burgdorferi) - Babesiosis (Babesia spp) - Anaplasmosis (Anaplasma phagocytophilum) - Tickborne encephalitis (Tickborne encephalitis virus)

Question 314

What patient population is particularly susceptible to Babesia?

Answer 314

Splenectomy

Question 315

Which antibiotic, that is useful against gram positive organisms, cannot be used in the lungs and why?

Answer 315

Daptomycin It is inactivated by surfactant

Question 316

What disease and responsible organism is transmitted by midges (Culicoides spp)?

Answer 316

Filariasis (Mansonella spp)

Question 317

What gram negative rod can cause antibiotic associated ischemic/hemorrhagic colitis as well as be a cause of neonatal sepsis?

Answer 317

Klebsiella oxytoca

Question 318

Which gram negative cocci displays the hockey puck sign on blood agar and what disease does is cause?

Answer 318

**Moraxella catarrhalis** ## Footnote Frequent cause of otitis media in children, COPD exacerbation in older adults Gram stain similar to Neisseria, **most produce beta lactamase** (AMP resistance)-**BQ!** and they are indoxyl butyrate positive

Question 319

What fungi can contaminate food and produce aflatoxins which are carcinogens and can cause HCC?

Answer 319

Aspergillus flavus (hence AFLAtoxins)

Question 320

What organism is being shown in this intestinal biopsy?

Answer 320

Microsporidia (apical aspect of cells containing intraceullular organisms)

Question 321

Which bacterial organism is a nonbranching, nonspore forming gram positive rod and is nonmotile and catalase negative, produces H2S on TSI slants causing a blackened butt (how it is distinguished from Listeria and Lactobacillus spp) and is intrinsically resistant to vancomycin?

Answer 321

Erysipelothrix rhusiopathiae

Question 322

Which organism is the cause of adiaspiromycosis, a benign granulomatous infection with characteristic large walled spherules?

Answer 322

Chrysosporium

Question 323

What virus causes subacute sclerosing panencephalitis (SSPE)?

Answer 323

Measles (risk is ~0.001%, average incubation of 7 years)

Question 324

What organism is shown here?

Answer 324

Babesia! Usually will see ring forms predominate which are similar to plasmodium but the Maltese cross is characteristic

Question 325

**DEFINITE BOARD Q!** Stem gives a kid with diarrhea. What virus is this?

Answer 325

Rotavirus

Question 326

What is the mneumonic for remembering the gram negative oxidase POSITIVE organisms?

Answer 326

The enterobacteriaceae are by definition oxidase negative (oxidase neg glucose fermenters--EXCEPT for Plesiomonas). To remember the gram negatives are ARE oxidase positive: "one can hallucinate on ***PCP*** a ***VAN*** driven by an ***OX*** named ***B**ruce **M**an*" Pseudomonas Campylobacter Pasteurella Vibrio Aeromonas Neisseria Brucella Moraxella

Question 327

What disease and responsible organism is transmitted by chiggers (Trombiculid mite)?

Answer 327

Scrub typhus (Orientia tsutsugamushi)

Question 328

What organism is being shown?

Answer 328

Aspergillus this one is probably Niger based on the pigment but fumigatus and flavus will look just like this only no pigment Neutropenia or phagocyte dysfunction (eg, CGD) is the key risk factor for invasive aspergillosis because neutrophils are the primary defense.

Question 329

What are the major causes of pneumonia in the setting of bronchiectasis and cystic fibrosis?

Answer 329

Pseudomonas aeruginosa, Burkholderia cepacia, Staphylococcus aureus

Question 330

Which virus causes this cytopathic effect?

Answer 330

RSV ## Footnote Syncytia in Hep2 cells (syncytia can be produced in various cell types by measles, parainfluenza and mumps viruses) Time to CPE: about 14 days *\*PMK=Primary Monkey Kidney, Hep2/HeLa=Human Epithelial Cells, HDF=Human Diploid Fibroblasts*

Question 331

What are the major causes of pneumonia in the setting of COPD?

Answer 331

Haemophilus influenza, Moraxella catarrhalis, Legionella pneumophilia

Question 332

Where can Cryptosporidium be found in an infected host? ## Footnote a) adherent to small intestinal brush border b) within an intracellular apical vacuole c) interdigitated between enterocytes d) in foveolar gland crypts of the stomach e) intracytoplasmically within enterocytes

Answer 332

**b) within an intracellular apical vacuole** On light microscopy, Cryptosporidium appears to be small (8-15 um) round organisms attached to the extracellular brush border. However, ultrastructural studies have determined that the organism is located in a unique position within an intracellular, yet extracytoplasmic apical vacuole. Isospora interdigitates. Microsporidium is intracelluar. Strongyloides is found within the crypt epithelium.

Question 333

What is the criteria for evaluating prosthetic joint infections on frozen section?

Answer 333

\>5 neutrophils per HPF in 5 different hpfs, excluding surface exudate and fibrin, has sensitivity of 29% and specificity of 95%

Question 334

What spp of Schistosoma produces intestinal schistosomiasis?

Answer 334

Schistosoma intercalatum *Mansoni and Japonicum effect the liver and hematobium effects bladder* Schistosoma found in snail infested water and migrate through bloodstream to mesenteric and pelvic vessels, releases eggs into the bloodstream which are lodged in small capallaries. Some eggs penetrate bowel or bladder wall to be excreted in stool or urine.

Question 335

How is the modified acid fast stain different than the regular acid fast stains and what organisms can it help identify?

Answer 335

Fite (modified) acid fast stain uses a weaker decolorizing agent and is good for "weakly" acid fast organisms such as: -Nocardia spp, Cryptosporidium, Isospora, Cyclospora, Sarcocystis, and Legionella micdadei

Question 336

If you see this picture of a fragmenting nucleus in this flagellate, what is your diagnosis?

Answer 336

Dientamoeba fragilis Usually asymptomatic but can cause diarrhea and anal pruritus and in fact is often co-infected with Enterobius vermicularis

Question 337

What is the hippurate hydrolysis test and what organisms does it help identify?

Answer 337

Presumptive ID of Campylobacter jejuni, Listeria monocytogenes, Strep agalactiae, Gardnerella vaginalis and Legionella pneumophila (all hippurate hydrolysis positive) Uses ninhydrin reagent; blue purple color indicates a positive result

Question 338

What is the lysozyme test and what organism does it ID?

Answer 338

Nocardia spp Most bacteria are inhibited by lysozyme so growth in lysozyme containing broth medium is indicative of Nocardia spp

Question 339

Which virus causes this cytopathic effect?

Answer 339

Enteroviruses (including coxsackie A and B, echovirus, poliovirus) ## Footnote Causes an angular, tear shaped cells that can be focally swollen or glassy. Time to CPE: 1-7 days Seen best in primary monkey kidney (PMK) or human diploid fibroblasts (HDF)

Question 340

What disease and responsible organism is transmitted by dog and cat fleas?

Answer 340

Double pored dog tapeworm (Dipylidium caninum)

Question 341

What serogroups of N meningitides cause the majority of disease in the US and which of those is not represented in the tetravalent vaccines available?

Answer 341

Serogroups B, C and Y cause majority of disease in US Serogroup B not represented in vaccine

Question 342

What is Lemierre syndrome and what organism causes it?

Answer 342

Tonsillitis complicated by septic thrombophlebitis of the internal jugular vein Caused by Fusobacterium necrophorum (also associated with placental infections)

Question 343

Which organism has the largest egg?

Answer 343

Fasciola Fasciola hepatica and Fasciolopsis buski have the largest human parasite eggs known (150 um in diameter)

Question 344

What spp of plasmodium is known for causing nephrotic syndrome?

Answer 344

P malariae \*also only spp to have quartan (72 hour) fevers

Question 345

What is the MLSB phenotype in staph/strep and why is this clinically important?

Answer 345

These strains have methylase enzyme (ermA or ermC) which alters ribosomal target. Suspected when isolate is noted to be resistant to erythromycin but susceptible to clindamycin. CLSI suggests D zone test on all staph aureus and on CNS by request. \*NEW 2013 CLSI guideline--requirement for beta streptococci

Question 346

What aspergillus spp is resistant to amphotericin B and has this colony morphology?

Answer 346

A. terreus

Question 347

What medium can be used to distinguish between Cryptococcus gattii and neoformans?

Answer 347

Canavanine glycine bromthymol blue agar (CGB agar) can be used to distinguish between C. gattii and C. neoformans.  C. gattii is blue on this medium.  Requires genotyping for confirmation.

Question 348

What is the basis for the hemadsorption test?

Answer 348

The viruses that express the surface antigen, Hemagglutinin, will bind to sialic acid containing receptors on respiratory epithelial cells and then will become expressed on infected cells (the basis for the hemadsorption test) Hemadsorption positive viruses: Influenza A and B, parainfluenza and mumps

Question 349

Describe the bile esculin test and what is it used to identify?

Answer 349

IDs enterococci and group D strep (Strep bovis) Both are able to hydrolyze esculin in the presence of bile Bile esculin agar slant inoculated and incubated for 24 hours. Diffuse blackening of the medium indicates esculin hydrolysis. Rapid spot versions of this assay also available.

Question 350

What is the Kaufman White typing scheme?

Answer 350

ID of Salmonella spp ## Footnote – O somatic antigens – cell wall – H flagellar antigens – Vi capsular antigen –Found in S. Typhi only

Question 351

Which bacteria causes UTI in older males with obstructive uropathy?

Answer 351

Enterococcus

Question 352

What is the procedure to process TB cultures?

Answer 352

– NaOH ± N-acetyl-cysteine – Centrifuge – Neutralize, add albumin to stabilize, continue with staining and culture

Question 353

What bacteria is seen growing in this Staph streak test as pinpoint colonies?

Answer 353

**Haemophilus spp** ## Footnote A phenomenon called satellitism. This is due to the ability of S. aureus to synthesize V factor (NAD), and releases X factor (hemin) by lysing blood. A colony of possible Haemophilus species can be subcultured to an SBA plate and streaked as a lawn. A single streak of S. aureus is made through the inoculum . After overnight growth in a CO2 enriched environment, the haemophilus conlonies may be observed within the hemolytic area adjacent to the staphylococcal growth.

Question 354

Which non spore forming gram positive bacillus is a common cause of CSF shunt infections?

Answer 354

Propionibacterium

Question 355

What diseases and responsible organisms are transmitted by the Aedes spp of mosquito (most commonly Aedes aegypti and Aedes albopictus)?

Answer 355

Arboviral disease including dengue virus, yellow fever virus, and Chikungunya virus

Question 356

This organism is acquired through ingestion of undercooked freshwater fish, the egg is 30 um, found in parts of Asia, causes chronic biliary infection.

Answer 356

Clonorchis sinensis

Question 357

What disease and responsible organism is transmitted by the black fly (Simulium spp)?

Answer 357

Onchocerciasis "river blindness" (Onchocerca volvulus)

Question 358

What are the treponemal and nontreponemal lab test for Treponema pallidum and what are the current CDC screening recommendations?

Answer 358

Treponemal: FTA-ABS, TP-PA, syphilis IgG by microhemagglutination or EIA Nontreponemal: RPR and VDRL Nontreponemal antibodies tend to wane with treatment or in late infection whereas treponemal antibodies remain positive indefinitely CDC Rec: screening with a treponemal specific test, specifically syphilis IgG by EIA. This results in fewer false positive results but positive tests should still be confirmed using a nontreponemal test to show disease activity

Question 359

In viral culture, which viruses grow best in: 1) Primary Monkey Kidney cells (PMK) 2) Hep2/HeLa cells 3) Human Diploid Fibroblasts (HDF)

Answer 359

1) Influenza, mumps, parainfluenza 2) Adenovirus, RSV 3) Rhinovirus, CMV, HSV \*Enteroviruses (Coxsackie A & B, echovirus, poliovirus) grow equally well in PMK and HDF

Question 360

What virus shows LANA1 positivity by IHC in a speckled nuclear pattern?

Answer 360

HHV8

Question 361

Which of the following mycobacteria spp is nonchromogenic, slow growing and grows at 30C but not 37C? ## Footnote a) M bovis b) M. haemophilum c) MAC d) M. leprae e) M. marinum

Answer 361

b) M. haemophilum

Question 362

Patients with the following immunodeficiencies are susceptible to what parasitic infections: 1) T cell (cellular) immunodeficiency 2) B cell (humoral) immunodeficiency 3) Splenectomy

Answer 362

1) Many! (ie Toxoplasma, Crytosporidium, Cystoisospora, Cyclospora, microsporidia are more common) while others (strongyloides) are more severe 2) Giardia more common 3) Babesia more severe

Question 363

What is a main difference between Candida glabrata and other spp of Candida?

Answer 363

Glabrata dose not produce hyphae or pseudohyphae!

Question 364

What are the characteristic biochemical properties of staph lugdunensis and why is it important to ID?

Answer 364

It is often positive by the slide coagulase test but negative by the tube coagulase test, PYR positive, ornithine decarboxylase positive It causes infections similar in severity to staph aureus