micro Flashcards Preview

Step > micro > Flashcards

Flashcards in micro Deck (237):
1

woman with a painful vaginal ulcer and bilateral inguinal lymphadenopathy. negative tzanck and VDRL.
dx and tx?

haemophilus ducreyi, chancroid
tx - ceftriaxone or azithromhcin

2

virus with the leading risk for developing hepatocellular carcinoma?

hepatitis b

3

kaposi sarcoma belongs go which viral family?

hhv 8
herpes viruses incl hsv1 hsv2 and roseola (hhv6), EBV, CMV, and varicella

4

CSF for bacterial meningitis will have what characteristics?

high opening pressure
high protein
pleocytosis with PMN predominance
low glucose

5

previously healthy pt with a history significant only for mitral valve prolapse presenting with endocarditis like symptoms

strep viridans:
s. mutans
s. sanguinis
s. oralis
s. mitis

6

tx for hhv8?

alpha interferon

7

oxidasd negative motile GNR that is beta hemolytic on macconkey agar but light green with black centers on hektoen agar

salmonella

8

pt with new palpitations, chest pain, systolic murmur (mitral regurg), elevated cardiac enzymes. bx would show diffuse myocardial defeneration and necrosis with inflammatory infiltrate

cozsackie virus
naked ssrna

9

h. pylori infection is a risk factor for?

gastric adenocaecinoma and b-cell hodgkin gastric lymphoma (AKA MALT lymphoma)
most h. pylori infections are asymptomatic (not manifesting as PUD in the majority)

10

what PPE is recommended in a ptmwith c. diff?

non sterile gloves and gown
also must use soap and water to wash hands. alcohol based sanitizer is not sufficient

11

a pt with chronic granulomatous dz are at increased risk of infection with organisms with which feature?

catalase positive organisms
pt is NADPH osidase deficient
s. aureus, burkholderia cepacia, serratia, nocardia, aspergillus

12

what is burkholderia cepacia?

catalase positive, non lactose fermenter, gram neg cocobaccilli
opportunistic pathogen causing pneumonia in immune compromised hosts(cf, cgd)

13

a pt presents with mycoplasma pneumonia and anemia. he is given azithromhcin and both symptoms improve. why?

m. pneumoniae can cause intravascular hemolytic anemia due to similar Ags and cold agglutinins. the anemia resolves when the cold agglutinin IgM levels lower.
m. pneumo is also associated with stevens-johnson syndrome, arthralgia, encephalitis, arrythmia, and bullous myringitis

14

an infant presents to the er following a seizure and a 12 hour history of fever. 3 days after discharge she develops a maculopapular rassh on her trunk. dx?

roseola (hhv6)
the key is a high fever followed by a maculopapular rash on the trunk 3-5 days later
tx = supportive

15

unvaccinated kid presents with fever, runny nose, cough, bilateral conjunctival injection, and small white spots with erythematous base on buccal mucosa. dx and likely to develop what additional symptom?

rubeola (measles)
maculopapular rash

16

a pt with a history of smoking and alcohol abuse presents with malaise and cough with 2 month duration. yellow sputum with streaks of blood. poor dentition, ginivitis, and large submandibular nodes. ronchi in right upper lobe.

actinomycosis
systemic infection occurs when mucosa is disrupted (poor dentition)
pulmonary actinmycosis can follow aspiration.
dx - filamentous branching pattern
tx -penicillin

17

a kid presenting with epiglottitis probably has what in his history?

missed his H. flu vaccine.

18

presence of pyrrolidonyl arylamidase is associated with?

Strep pyogenes
(PYR positive)

19

pt on chemo presents with skin patches with an ulcerated appearance and occasional necrotic center.
increased PTT, neutropenia

psuedomonas aeruginosa
ecthyma gangrenosum is caused by psuedomona bacteremia

20

pt is newly diagnosed with CML and begins tx. later presents with HA and an eye problem. PE shows tenderness of paranasal sinus, left orbit swelling, cellulitis, mild proptosis, ptosis. bx shows hyphae with acute angles

aspergillus fumigatus

21

Nicotinic blockade (diplopia, dysphagia) and muscarinic blockade (dry mouth) is suggestive of

The 3 D's suggests Ingestion of C. botulinum toxin
Inhibits ACh release
Can be partially overcome by high-rate repetitive nerve stimulation (CMAP)

22

Tx of a pt with a recent heart valve replacement pt that has cultures poitive for cat + coag - Staph

Staph epidermidis
Vanco

23

Kidney transplant patient with pleuretic chest pain, cough, and low grade fever. Infiltrate in lower lobe of lung. Not responding to abx. Brnchoalveolar lavage reveals red round organism on mucicarmine staining

Cryptococcus neoformans
This is the only pathogenic fungi with a polysaccharid capsule (virulence factor). Stains red with mucicarmine
Can present as meningoencephalitis or lung dz in immunocompromised

24

Characteristics of scarlet fever (S. pyrogenes

fever, pharyngitis, sandpaper-like rash, circumoral pallor, strawberry tongue

25

Physical characteristics of candida

Pseudohyphae with bloastoconidia

26

Physical characteristics of blastomyces

Yeast with distinctive broad-based budding

27

Physical characteristics of Coccidioides

Spherules with endospores

28

Physical characteristics of cryptococcus

Capsule (India ink stain)

29

Physical chracteristics of Histoplasma

Small oval yeast within macrophages

30

Nearly all Candida infections can be treated with

fluconazole

31

Woman with recurrent transient pulmonary infiltrates and history of bronchial asthma, especially in winter. She does use albuterol. Labs demonstrate Eosinophilia. CT shows proximal bronchiectasis.

Aspergillus fumigatus
Allergic bronchopulmonary aspergillosis
Pts with a history of asthma or CF are prone to allergic hypersensitivity reaction to the fungus.

32

Pt with persistant fever, chills, fatigue, dyspnea for 10 days. History significant for splenectomy and recent travel to Conneticut. Bilateral infiltrates on CXR. Labs show normocytic normochromic anemia with a cross-shaped intraerythrocytic inclusion

Babesiosis
Tick borne infection (like borrelia)
Coinfection is common

33

Live cycle of Hep B

dsDNA -> +RNA template -> dsDNA progeny

34

Apiration pneumonia

Lung parenchyma infection
Aspiration of oral microbes (anaerobes)
Presents days after aspiration with fever, cough, and sputum. Usually in RLL and can progress to abscess
Tx - Clindamycin

35

Aspiration pneumonitis

Lung parenchyman inflammation
Aspiration of gastric contents presenting hours after event. Range os symptoms and CXR infiltrates resolve without abx
Tx - supportive

36

Farm worker presenting with shortness of breath, fatigue, myalgia, and severe retroobital headaches. Elevated ALT/AST and throbocytopenia

Coxiella burnetii
Q fever - acute phase
Inhalation of bacteria from animal waste
Fatal if untreated and progressis to infective endocarditis

37

A female pt presents with pelvic pain, fever, and chills following a D&C 2 days ago. On PE she has lower abdominal tenderness, an open os, foul-smelling tissue in vaginal canal and moderate CVA tenderness

Septic abortion = infection of the retained products of conception in the uterus
S. aureus is the most common cause but can also be E. coli, Group B strep
Organisms usually stay in the placenta but pt can become septic if they enter the intervillous space
Tx - abx and surgical evacuation
Can have long term complications (Asherman syndrome) involving adhesions in the uterus leading to amenorrhea and infertility

38

Co innoculation of H. flu and S. aureus allows H. flu to grow larger colonies on sheeps blood agar. Why?

S. Aureus provides NAD+ (Factor V) "satellite phenomenon"
Hemattin (Factor X) will be released from lysed RBC's

39

How do you manage a pt with a recent staph infection that presents with fever and tenderness over the upper lumbar vertebrae without overlying skin changes?

Pt probably has vertebral osteomyelitis. Hmatogenous spread. Initial evaluation should include blood cultures and MRI of the spine.

40

If soil is heated to 100C for 15 min what bacteria could survive?

Bacillus anthracis
Just because it's in the soil in the form of a spores. Spore forming bacteria can survive boiling water

41

reovirus with dsRNA

Rotavirus

42

Flu-like febrile illness with myalgia, joint pain, retro-orbital pain, bleeding, rash, thrombocytopenia, leukopenia, and elevated LFT's following travel to mexico

Dengue Hemorrhagic fever
Do have life long immunity following infection, but can get a secondary infection with a different serotype and can cause a more severe illness

43

Sexually active female pt with UTI. Organism is Gram + cocci, catalase +

S. saprophyticus
Also noboviocin resistant

44

Pt being treated for Hodgkins dz presents with fever, chills, and malaise. Culture grows Gram positive rods with a very narrow zone of beta hemolysis on blood agar and grow well in the cold.

Listeria monocytogenes
Need cell-mediated immunity to clear them
Tumbling motility at 22C

45

A neonate presents with clenched muscles and difficulty feeding following an uncomplicated home delivery. The umbilical cord with covered with soil. Other than hygienic umbilical cord care, what other strategy could have prevented the condition?

Neonatal tetanus
Prevent with: good hygienic umbilical care and vaccination of the pregnant mom

46

A grandfather had HA, myalgia, malaise, cough, and throat pain and was set home on conservative management. He presents 5 days later with dyspnea, chest pain, and productive cough and is admitted

Pt initially had influenza
Elderly pts can develop a secondary bacterial pneumonia due to damaged mucocilliary epithelium. Generally acquire Strep pneumo, Staph aureus, or H. flu

47

How does Corynebacterium diphtheriae acquire virulence?

Transduction or lysogenization of exotoxin (Tox gene)

48

A pt with C. diff is placed on a po macrocyclic abx that is bacteriocidal and minimal systemic absorption

Fidaxomicin
inhibits RNA polymerase

49

What is the most important factor in the pathogenesis of Shigella dysentery

Mucosal invasion (M cells that overlie Peyer's patches)

50

The virulence in rabies is due to its ability to bind which receptor?

Nicotinic Acethlcholine receptors

51

A kid has a 2 day history of diarrhea and his puppy had diarrhea about a week ago. Kid is up to date on vax. Stool is negative for ova and parasites

Campylobacter jejuni can be transmitted from animal to human.
Yersinia too
Abdominal pain can mimic appendicitis

52

What is malignant otitis externa?

Severe ear infection seen in DM pts. Presents with ssevere ear pain and drainage and granulation tissue. Can progress to osteomyelitis of the skull
Pseudomonas aeruginosa - non lactose fermenting, oxidase +, Motile GNR
Tx - Ciprofloxacin

53

A pt with recent viral esophagitis and pneumocystis pneumonia is presenting with meningitis. CSF has high protein and pleocytosis. Positive latex agglutination for soluble polysaccharide Ag

Pt likely has HIV
Meningitis due to cryptococcus neoformans
Light microscopy of CSF would reveal budding yeast.

54

The adult version of the S. pneumo vaccine contains which components?

Outer polysaccharide covering
This is found in both the conjugate and unconjugated vaccines

55

A pt with pyelonephritis has a culture positive for motile Gram negative rods demonstrating a green metallic sheen on eosin methylene blue (EMB) agar and hemolysis on blood agar

E. coli
Major virulence factor in UTIs = Fimbrial Ag

56

What perinatal care should be given to prevent a Strep aglactiae infection in a neonate?

Interpartum ampicillin

57

pt presents with fever and jar pain. PE shows a swelling of the postauricular area extending to the angle of the mandible. Dx?

Parotitis ( due to dehydration, intubation)
S. aureus
Elevated amylase confirms dx

58

Where is the primary site of ribosome synthesis and assembly?

nucleolus
All ribsomal rRNA is made here except 5S

59

A double stranded linear segmented RNA virus?

Rotavirus

60

Vector in Trypanosoma cruzi?

Reduviid bug

61

A gram + diplococci that causes pneumonia

S. pneumo

62

Staghorn calculi are formed by?

Urease producing microorganisms
Staph species
Ureaplasma
Proteus (most common)
Klebsiella
Pseudomonas

63

What is a worrisome complication of mucormycosis?

Meningitis

64

A pt presents with right upper quadrant pain, jaundice, and fever

Bacterial cholangitis
Long history of gallstones causes blockage of the bile duct leading to infection.
Bacterial infection of bile duct. Usually enteric GNR

65

Most common cause of osteomyelitis in a healthy child

S. aureus

66

Most likely cause of meningitis in a 2 day old infant?

Group B strep
Most common cause in kids

67

A female is brought to the ED for suspected appendicitis, but US revealed that the mass was within the pelvic cavity. She needs a different emergent surgical procedure

Chlamydia
Causes scarring of the fallopian tubes leading to ectopic pregnancy

68

A viral cause of seizures in an HIV pt with a CD count of 150

HSV 1 or HSV 2

69

Good alternative to treat gram + organisms in a pt allergic to penicillin

Macrolides (erythromycin)

70

a pt has a sore throat, hoarseness, productive cough, and elevated gamma-glutamyltransferase level. CXR shows lobar pneumor. Tx = cefuroxime. Dx?

Klebsiella pneumoniae
Nosocomial and CA pnumonia
Chronic alcoholics have elevated gamma-glutamyltransferase
GN encapsulated rod on sputum smear
mucoid colonies on MacConkey
tx = second gen cephalosporin and an aminoglycoside

71

A homosexual man with steatorrhea

Giardia

72

Viruses of the reoviridae family have what characteristics?

ds segmented RNA with icosahedral nucleocapsids
IE - rotavirus, coltivirus

73

What step of proteins translation does C. dpitheriae's toxin inhibit?

EF2 toxin
inhibits elongation (translocation)
Complexes with GTP to bind the ribosome

74

a pt with a history of mitral valve prolapse presents with subacute endocarditis that are throwing microemboli in the hands (Janeway, Osler), retina (Roth spots) dx?

Step veridians
Most commone cause of SAE in the setting of mitral valve prolapse

75

A pt with Aschoff nodules and a new murmur

Rheumatic heart dz

76

10 y/o with seizures, poor school performance, CSF findings consistent with viral infection. Respiratory secretions + multinucleated giant cells with intracytoplasmic and intranuclear inclusions. Rash on the trunk

Measles

77

I a pt has a penicillin allergy they should receive?

Erythromycin
Macrolide against Gram + and Gram -

78

A neonate presents with conjunctivitis on day 13 of life. Dx?

Chlamydia trachomatic (D-K) at risk of getting pneumonia

79

Trismus is?

Lock jaw
Seen in tetanus

80

Tenesmus?

Sensation of needing to empty the bowel although there is no stool to pass. Inflammatory dz of the bowel

81

Ziehl-Neelsen stain is used for?

Acid fast bacteria (M. TB)

82

Schistosoma haematobium causes which type of bladder cancer?

Squamous cell carcinoma (SCC)
Keratin pearls on bx

83

Which other organism carries a toxin with a similar MOA as Bacillis anthracis?

Edema factor = increase in intracellular cAMP
Also seen in cholera toxin

84

Germ tube postivie fungus

Candida albicans
Germ tube = hypahe

85

Germ tube negative fungus

histoplasmosis, blastomycosis, coccidioidomycosis

86

HIV pt (CD4 = 22) with hemiparesis, visual defects, cognitive impairment. Negative LP but bright spots are seen on the MRI. Dx?

JC virus
Multifocal leukoencephalopathy
CD4

87

Regan Lowe medium is used for?

Bordetella pertusis
Culture from a calcium alginate swab (bacteria do not transfer well on cotton)

88

What infection can occur when an HIV pts CD4 count drops

Disseminated Mycobacterium avium-intracellulare infection
TB like dz
Azithromycin prophylaxis

89

A 12 y/o presents with mental status changes characteristic of encephalitis x 1 wk. CSF has elevated WBCs, mildly elevated protein, and RBCs. CT show focal unilateral pathology of the temporal lobe. Dx?

Encephalitis due to HSV1
elevated proteins + RBCs in CSF = HSV1 encephalitis

90

A poultry farmer in ohio presents with pneumonia. XR lesion in the upper lung lobe and hilar lymphadenopathy. Dx?

Histoplasmosis
Ohio and Mississippi river valley
Found in bat droppings

91

7 y/o immigrant presents with red itchy eyes with swelling, cough, runny nose. Oral cavity has small lesions with white centers. Dx?

Rubeola (measles)
2 C's - cough, coryza, conjunctivitis, and Koplick spots
Expect to see a rash 1-2 days after the appearance of the Koplik spots that will start at the head and move its way down

92

What is the neurological syndrome associated with Rubeola infection

Subacute Sclerosing panencephalitis (SSPE)
Occurs 7-9 years after Rubeola infection
Personality changes, lethargy, difficulty in school, odd behavior. Can progress to dementia, myoclonic jerking, and eventual flaccidity a decorticate rigidity.

93

After a camping trip that included interaction with many types of animals a pt presents with RUQ pain, nausea, and vommiting. An enlarged liver with a cyst is found. Dx and Tx?

Echinococcus granulosus
Albendazole
parasitic tapeworm in feces (dog)
Albendazole inhibits tubule polymerization. Cannot go straight to surgery b/c the contents of the cysts causes anaphylactic shock

94

Which organisms cause struvite stones?

Urease positive
Proteus
Klebsiella
Staphylococcus
Ureaplasma
Pseudomonas
Alkaline urine with multiple magnesium ammonium phosphate crystals

95

What is the MOA of enfuvirtide?

Prevent entry of viral particles into the target host cell (gp41 mediated fusion)

96

What is the MOA of rltegravir?

Inhibits integrase and prevents viral integration into the host genome

97

MOA of maraviroc?

entry inhibitor
Binds CCR-5 on T cells and monocytes and block its interaction with gp120

98

Specific test for Syphillus infection?

Fluorescent treponemal antibody absorption test
VDRL and RPR are more sensitive but less specific

99

Virulence factor that allow S. pneumo to colonize the lung?

IgA protease
cleaves secretory IgA Ab in mucosal surfaces allowing for bacterial colonization

100

Which bacteria have lipopolysaccharide?

outter membrane of Gram-negative bacteria. Induces a strong immune response by the host

101

Pt presents with high fever, black vomitus (dark-colored blood in the vomitus as a result of GI bleeding), jaundice, HA, and back pain. Dx?

Yellow fever, flavivirus
Dx with rtPCR
Bx = councilman bodies (acidophilic inclusions in liver), but bx is usually not recommended due to bleeding risk

102

How is be facial n. palsy differentiated from stroke?

If the pt can furrow the brow - stroke
if the whole half of the face is paralyzed - borrelia

103

What syx are found in the second phase of Borrelia infection?

CN VII palsy, transient arthralgias, aV nodal block, secondary annular rash, carditis
Tx - doxycycline
However, if pt has cardio or neuro involvement tx with IV ceftriaxone

104

What makes Bells palsy different from facial n. palsy?

Bells palsy is idiopathic origin
Facial n. palsy is a known cause (ie borrelia)

105

A woman presents with a vaginal infection due to candida following a course of tetracycline. Why?

Loss of gram + faculative anaerobes
Lactobacilli make up the normal vaginal flora
Dx - KOH prep

106

What type of Hypersensitivity rxn is PSGN

Type III (Arthus rxn)
Ag-Ab complexes are deposited in the GBM and activates complement

107

What is a type II HS rxn?

Ab mediated but IgG binds Ag on the surface of a target cell - autoimmune

108

In CMV retinitis, what would be a late finding in the dz?

Retinal detachment
CMv is a common cause of blindness in AIDS pts
Presents with rapidly diminishing sight and on fundoscopy cotton-wool exudates, necrotizing retinitis, perivascular hemorrhages, and ultimately retinal detachment
Tx - ganciclovir and foscarnet

109

Which two toxicities are associated with isoniazid use?

Neurotoxicity (Add B6)
Hepatotoxicity

110

Infectious cause of CHF in a pt with no RF's?

Coxsackie B
Icosahedral member of the picornaviridae family

111

Which two agars can be used to culture Bordetella pertussis?

Bordet-Gengou (potato) agar
Regan-Lowe medium
Transfer with calcium alginate swab

112

Major cause of viral pink eye?

Adenovirus
Naked icosahedral dsDNa
Self-limited, no tx

113

When would you use Loffler medium?

Corynebacterium diptheriae

114

Maraviroc prevents?

CCR-5 binding to gp120

115

Enfuvirtide prevents?

gp41 mediated fusion

116

Why does Hep D need Hep B?

Coating of the viral particles
HDV needs HBV sAg so that it can enter future hosts

117

When Aspergillus forms a fungus ball within a preexisting cavity, what is this process?

Colonizing
Causes a lung hypersensitivty rxn in allergic bronchopulmonary aspergillosis in individuals with asthma

118

PSGN is which type of HS rxn?

Type III = Ag - Ab complexes leading to complement activation
Type II = Ab mediated

119

What is a clue cell made of and which infection does it suggest?

Clue cell = epithelial cell covered with gram-variable rods
Gardnerella vaginalis
Thin off-white discharge with fishy odor, imbalance of vaginal flora, see clue cells on wet mount
pH > 4.5, + whiff test (amine odor with KOH)
Tx - metronidazole or clindamycin

120

In TB cord factor is?

A virulence factor
Inhibits PMNs, destroys mitochondria, and increases release of TNF

121

8 y/o presents with rapid and irregular movements of his hands and funny faces. He also has several circular, faintly erythematous lesions on his abdomen. What is the mechanism?

Cross-reactivity of Ab against bacterial and host Ag
Anti-M Ab cross-react and attack cardiace and CNS Ag

122

If a person has Anti-HBs Ab then they?

Have been vaccinated against HBV

123

Why add clavulanic acid to amoxicillin treatments?

Decrease drug cleavage by bacterial cells
Sulbactam and tazobactam are beta-lactamase inhibitors.
Expands amoxicillin specturm of actitivy to include stains of B-lactamase synthesizing bacteria

124

MOA of zidovudine?

Inhibits 3'-5' phosphodiester bond formation
Nucleoside reverse transcriptase inhibitor
Thymidine analog (no 3'OH group)

125

A pt tests positive for HBsAG and elevated LFTs. The most likely outcome of the infection is?

Complete resolution
95% of HBV infected adults have acute hepatitis with mild or subclinical syx that eventually completely resolve

126

What mechanism do bacteria use to become resistant to rifampin?

Alter structure of enzymes involved in bacterial RNA synthesis
Inhibits bacterial RNA polymerase
Red-orange body fluids
Inhibits transcription

127

Pt presents with a urethral dischage that is rich in neutrophils with intracellular gram negative diplococci. He is given IM ceftriaxone but his syx do not improve. What tx should he receive next?

PO azithromycin
It should have been assumed that he had a co-infection of neisseria and chlamydia and he should have received ceftriaxone + doxy or azithromycin

128

Tx for enterobius?

Albendazole
Scotch tape test worm
Pyrantel pamoate - 2nd line

129

What is the mechanism for naficillin tx is Staph aureus?

Poor interaction with binding proteins
Altered penicillin-binding protein in the peptidoglycan cell wall that does not bind beta-lactams effectively

130

Elderly pt presents with acute mental status change, seizure, HA, focal neurologic deficits. CSF reveals hemorrhagic lymphocytic pleocytosis with NL glucose. ABN MRI signal in the temporal lobes. Dx?

HSV encephalitis
Tx - acyclovir

131

A pt with methicillin-resistant S. aureus and started on an IV abx. A week later he has mascle pains and elevated creatine phosphokinase that resolves with d/c. What is the MOA of the abx?

Maintenance of membrane potential
Daptomycin - gram positive organisms. Causes depolarization of bacterial cellular membrane and inhibition of DNA, RNA, and protein synthesis. Dapto is associated with increased creatine phosphokinase and increased incidence of myopathy

132

A pt with primary TB infection is put on Isoniazid monotherapy. This would result in?

Selective survival of bacterial cells secondary to gene mutation
Active TB is never treated with monotherapy due to the fast emergence of mycobacterial abx resistance from rapid, selective gene mutations.

133

A strain of Candida develops a mutation in the enzyme responsible for synthesizing a fungal cell wall polysaccharide. This strain would be resistant to?

Caspofungin
Inhibits the synthesis of the polysaccharide glucan
Azoles, Ampho - inhibits ergosterol in the cell MEMBRANE

134

What lab findings would suggest that a HBV pt has progressed to chronic HBV?

If HBeAg persists for several months and host anti-HbeAg remains low, suspect chronic HBV with high infectivity

135

Which antifungal causes a decrease in ergosterol incorporation into the cell membrane

Nystatin
Polyene antifungals (ampho, nystatin) act by binding ergosterol in the funagl cell membrane

136

MOA of Triazoles

Inhibit ergosterol synthesis
-azoles

137

MOA of Fluctosine

Converted to 5-fluorouracil interferes with fungal RNA and protein synthesis

138

HIV pt presents with esophageal hyperemia and linear ulcerations. Dx?

CMV

139

HIV pt presents with patches of adherent grey/white pseudomembranes on endoscopy. Dx?

Candida

140

HIV pt presents with small vesicle and "punched-out" ulcers on endoscopy. Dx?

HSV-1

141

Pseudomonas treatments

Penicillins - ticarcillin, piperacillin
Cephalosporins - ceftazidime, cefepime
aminoglycosides - amikacin, gentamicin, tobramycin
fluoroquinolones - ciprofloxacin, levofloxacin
Monobactams, carbapenems

142

Pt presents with mono syx with 30% atypical lymphocytes. Serum fails to agglutinate horse RBCs. Dx?

CMV
+ agglutination (monospot) would suggest EBV
other causes of monospot negative mono are HHV6, HIV, and toxo

143

A DM pt presents with a black eschar around his nasal cavity. What test would confirm the dx?

Mucosal bx
Mucormycosis

144

Pathogenecity of H. flu depends on?

antiphagocytic polysaccharide capsule

145

Primary causes of hepatic abscesses?

underdeveloped country - parasitic (Entamoeba, echnococcal)
Developed country - bacterial (S. aureus)

146

Pt in the north east presents with flu like syx on intraerythrocytic inclusions on smear. Dx?

Babesiosis
Ixodes tick vector
Maltese cross

147

Pt with a UTI has gram-positive cocci in chains. Dx?

Enterococcus
gram positive cocci in pairs or chains
No hemolysis on blood again (gamma)
Pyrrolidonyl arymlamidase (PYR) +
Grow in bile and 6.5 % NaCl
Negative nitrites on UA

148

S. pneumo vaccine for adults includes which component?

Outer polysaccharide covering
Induces a T cell independent response
Also N. meningitidis and H. flu

149

S. pneumo vaccine for kids contains?

Conjugate vaccine = polysaccharide material attached to a protein Ag, more robust T cell response

150

Pt has a lung bx with spherules packed with endospores. Dx and recent hx includes?

Coccidioides
Recent travel to Arizona

151

Fungus passed through bird droppings?

Cryptococcus - pigeons, immunocompromised meningitis
Histoplasma - Mississippi and Ohio river basins, bird and bat droppings. Hx of cleaning bird coops or caving

152

Fungal rhinosinusitis with acute angles and septations

Aspergillus
Occurs in immunocompromised pt
Granuloma formation in the lung
V-shaped, narrow branching hyphae
Septations look like little bubbles within the organism on bx
Monomorphic, grows on decaying vegetation
Tx - Amphotericin

153

What process is most important for eliminating Listeria from the body?

Cell-Mediated Immunity
Intracellular bacteria are protected from circulating immune factors (Ab). Listeria is able to live within the macrophage with the action of listeriolysin O (pore-forming toxin selectively activated within acidified phagosomes)
Beta hemolytic (narrow), tumbling motility, grows at cold temps
Neonates are especially susceptible up to 3 months of age due to naive cell-mediated immunity
Contaminated dairy products

154

Skin lesions following the lymph nodes following a thorn prick

Sporothrix schenckii
Bx = granuloma with histiocytes, multinucleated giant cells, PMNs, surrounded by plasma cells
Forms subQ noddules and ulcers along the lymphatics
Dx - by culture
Tx - Itraconazole

155

EBV binds which host cell receptor for entry?

CD 21

156

Parvovirus binds which host cell receptor for entry?

RBC P Ag

157

Small ovoid bodies with Macrophages

Histoplasma
Seen in BM bx of immunocompromised
Hyphae on sabouraud agar
Can be dx'd with immunoassay and serology

158

nonlactose-fermenting, oxidase +, motile, GNR

Pseudomonas
Causes malignant otitis externa in elderly DM pts
Exquisite ear pain and drainage with granulation tissue in the ear canal

159

Doubly refractile wall with single broad-based bud

Blastomyces
Ohio miss river

160

Thick walled spherule filled with endospore

Coccidioides
Southwest

161

PYR +

Enterococcus
Strep pyogenes

162

CMV infection during pregnancy increases the risk of what to the unborn fetus?

Chorioretinitis
Sensorineural deafness
Seizures
Jaundice
Microcephaly

163

HHV 6 is? Syx?

Roseola
Occurs in

164

flulike illness + myalgias + retro-orbital pain + recent travel hx

Classic dengue fever
If pt also has thrombocytopenia and petechiae - Dengue hemorrhagic fever
ssRNA viruses with 4 serotypes, Flavirus

165

Why is HCV considered genetically unstable?

Lacks proofreading 3'-5' exonuclease activity in its RNA polymerase
Glycoprotein sequences also have a hypervariable region prone to mutation

166

Bartonella causes cat scratch fever and?

Bacillary angiomatosis in the immune compromised, culture negative endocarditis
Axiallary lymphadenopathy is common

167

Noneveloped ssDNA virus?

Parvo

168

Most common Catalse Problem organisms?

S. aureus
Burkholderia
Serratia
Nocardia
Aspergillus
Beware of these in a pt with Chronic Granulomatous dz (NADPH oxidase deficiency)

169

All rRNA (except 5S) is transcribed in the?

Nucleolus
Dense round structure
Contains ribosomal DNA, newly transcribed rRNA, and ribosomal proteins

170

Why do asplenic pts have more severe syx?

Defect in systemic bacterial clearance
Fxn of spleen red pulp = 1. Filter blood, 2. Site of opsonizing Ab synthesis (esp important for clearing encapsulated species)
Asplenic pts are prone to infection by encapsulated organisms (S. pneumo, H. flu, Neisseria)

171

What are the key characteristics of HSV encephalitis?

Potentially fatal complication of primary dz or reactivation
Necrosis of temporal lobe causing aphasia, personality changes, and classic syx of encephalitis

172

Changes in host range of a virus are usually due to a mutation in the?

Surface glycoprotein
Mediates virion attachment and fusion

173

STD with Deep, purulent painful ulcers with matted/suppurative lymphadenitis?

Chancroid
Haemophilus ducreyi
Dx - Gram stain, culture, PCR

174

STD with Painless, progressive, red serpiginous ulcerative lesions without lymphadenopathy

Klebsiella granulomatis
Dx - Gram stain, culture (tough), Bx (Donovan bodies)

175

Pt presents with vomiting two hours after ingesting a food with mayo. Dx?

S. aureus
Exotoxin was formed prior to ingestion
B. cereus also creates a stable exotoxin but look for hx of eating reheated rice

176

Diplopia
Dysphagia
Dysphonia

Botulism (12-36 hrs post consumption)
Dysphonia = difficulty speaking
Toxin prevents release of ACh

177

PE - tonsilar erythema with exudates
Microscopy - clumped Fram + bacter with polar granules that stain deeply with aniline dyes

Corynebacterium diphtheriae
Inhibits host cell protein synthesis by catalyzing the ADP-ribosylation of host cell elongation factor-2
Nonmotile, unencapsulated GPR found in cumps. Cytoplasm contains metachromatic granules that stain with aniline dyes (methylene blue)

178

Cause of cephalosporin resistant meningitis in a kid

Listeria
1st line tx = ampicillin
Causes dz in those with deficient cell-mediated immunity (kids and immunocompromised)
Cephalosporins would cover - H. flu, Neisseria, Srep agalactiae, strep pneumo)

179

HBV genome replication cycle

dsDNA -> + RNA -> dsDNA progeny
Replicates via reverse transcription

180

Genome, syx, tx, and route of transmission of adenovirus

Genome - dsDNA
syx - red eyes in croseded quarters (camp, military, dorms)
tx - supportive
transmission - direct contact, fecal-oral, respiratory droplets

181

HIV pt presents with tonic clonic seizure and two ring-enhancing focal lesion with surrounding edema in R frontal lobe. Dx?

Toxo - multiple ring-enhancing lesions with mass efect
Tx - Pyrimethamine + sulfadiazine, or pyr + clindamycin if allergic to sulfa drugs
Also add leucovorin (folinic acid)

182

Atypical pneumonia + watery diarrhea + smoking hx + recent travel on a cruise

Legionella
hyponatremia

183

Suspect gonorrhea and tx with?

Macrolide (chlamydia) and 3rd generation cephalosporin (ceftriaxone) (gonorrhea)

184

Morphology of Bordetella pertussis

Gram-neg coccobacillus

185

Which cell type secretes IFN gamma in a quantiferon test?

Th1
Macrophages secrete IL-2

186

Pt presents with pruritic rash (worse at night) on the palmsa. excoriations with small crusted red papules. Dx?

Scabies
Dx with skin scrapings from lesions showing mites, ova, and feces

187

MOA of isoniazid

Inhibits mycolic acid synthesis
Pathogen loses its acid fastness and stop proliferating

188

MOA of rifampin?

Inhibit bacterial DNA dependent RNA pol

189

Major virulence factor in epiglottitis?

Polyribosylribitol phosphaste
component of H. flu's capsule

190

A virus is identified to have a membrane envelope with a similar composition as its host. What could it be?

CMV, EBV, HHV etc
Herpesviruses bud through and acquire the lipid bilayer envelope from the host cell nuclear membrane
Most other viruses bud through the host membrane without acquiring a phospholipid membrane

191

Immigrant presents with tonic-clonic seizure. On MRI there is a cyst in the left sylvian fissure that has minimal enhancement and no associated edema. Dx and mode of transmission?

Neurocysticerosis
Ingestion of Taenia solium (pork tapeworm) eggs from the stool of tapeworm carriers (fecal oral route)
Common cause of seizures in central and south america
NOTE - eating contaminated meat does not cause neuro syx, just tapeworm infestation, nbd

192

What is used to treat rabies?

Inactivated vaccine
syx - agitation and muscle spasms progressing to coma

193

Infant with irritability, poor feeding vomiting, large head circumference. white-yellow chorioretinal lesions bilaterally. Enlarged ventricles with intracranial calcifcation on CT. Dx?

Toxo
Torches infection
Hydrocephay + intracranial calcification + chorioretinits

194

Agar for C. diptheria?

Cysteine-tellurite agair
Loffler's medium
(kid laughing at the telle)

195

How can you distinguish between toxo and Neurocysticercosis (Taenia solium) on seizure pt?

Immunocomp pt - Toxo
Travel to South America - Taenia

196

How does TB's cord factor establish virulence?

PMN inhibition
Mitochondrial destruction
TNF release

197

E. coli is able to cause sepsis by entering through the?

Urinary tract
Fimbriae are essential for colonization

198

Cause of fulminant hepatitis in pregnant women?

Hep E
Unenveloped, ssRNA
Fecal-oral
Asia, Africa, Mexico
No chronic dz
Higher mortality in preggo's

199

Fxn of the virulence factor found in the Peptidoglycan wall of S. aureus?

Protein A
binds the Fc portion of IgG -> impairs complement activation, opsonization, phagocytosis

200

Congenital rubella syndrome

classic triad = white pupils (congenital cataracts) + sensory-neural deafness, PDA
But also microcephaly, deafness
prevent with live MMR vax

201

Older woman is presenting with encephalitis, meningitis, flaccid paralysis, and a rash. dx?

West Nile virus (Flavivirus)
Encephalitis + flaccid paralysis + rash
+ ssRNA
Mosquito borne, see transmission in the sumer
Tx - supportive

202

Tx plan for cryptococcal meningitis?

Amphotericin B + flucytosine
followed by long term fluconazole

203

MOA of C. diff toxin?

Compromises the cytoskeleton integrity of intestinal mucosal cells
Disrupt actin cytoskeletal structure and intracellular signaling
toxin A - causes more inflammation and fluid secretion (enterotoxin)
Toxin B - is more cytotoxic

204

Why does HDV need HBV?

Coating of viral particles

205

Non lactose fermenting GNR causing syx in a pt with an indwelling catheter?

Pseudomonas aeruginosa

206

If you see viral gastroenteritis in US school kids assume it is?

Norovirus
Rotavirus has similar syx but rarely seen in the US due to vax's

207

Most likely route of infection of Listeria in immunocompromised?

Contaminated food

208

Water borne gastroenteritis with high mortality in Asian countries. Oxidase-positive GN bacilli that grow well on highly alkaline selective media?

Vibrio
Thiosulfate citrate bile salts sucrose again (TCBS)
Pts with achlorhydria (low gastric acid production) can get the disease from a lower infectious dose (this includes taking omeprazole)

209

Following an influena infection a pt presents with pneumonia due to?

Bacterial pneumonia
S. pneumo > S. aureus > H. flu

210

Pt presents with appendicitis. Most likely organism?

Usually polymicrobial with Bacteroides fragilis and E. coli

211

Botulinum toxin blocks?

Presynaptic excocytosis of ACh vesicles

212

In Mycoplasma pneumo, which Ab's cause the hemolytic anemia?

Cold agglutinins

213

While in central america a pt develops watery diarrhea with cramps n/v that resolves two days later w/o abx?

ETEC "traveler's diarrhea"
Heat labile (LT) and/or heat stable (sT) enterotoxins are endoded on a plasmid
LT = cholera like toxin, increases intracellular cAMP in gut mucosal cells by activating Gs
ST = increases cGMP

214

Tx for pseudomonas?

cephalosporins (Cefepime, ceftazidime)
Penicillins (ticarcillin, piperacillin)

215

Pt has dysuria and hematuria 2 weeks after visiting africa. U/S bilateral hydronephrosis and bladder wall thickening. Dx?

Schistosomiasis haematobium
Transmitted by snails
S. japonicum and S. mansoni cause intestinal and hepatic schistosomiasis

216

Lobar pneumonia in an alcholoic is caused by?

Aspiration of oropharyngeal contents (anaerobic bacteria: Fusobacterium, Peptostreptococcus, Bacteroides)
Common cause of lung abscesses

217

A baby born to a mom that was infected by HBV during the third trimester is likely to have elevated levels of what in her serum?

HBeAg
Infected neonates are at high risk for chronic infection but are usually asymptomatic with very minor clinical findings

218

Pt has pneumonia in the RUL. Encapsulated GNR that ferments lactose

Klebsiella pneumoniae

219

Linear ulcerations in immunocompromised?

CMV

220

Infection post dog bite that has mouse like odor on culture?

Pasteurella multocida
Tc - amoxicillin + clavulanate

221

A woman has a stillbirth at 18 weeks gestation that has pleural effusion, pulmonary hypoplasia and ascites. Dx?

Parvo
Nonenveloped ssDNA
Mom had reported arthralgias
Fetal hydrops = pleural effusion with secondary pulmonary hyoplasia and ascites

222

Grayish white vaginal discharge
Fishy odor
Clue cells

Gardenella
Anaerbobic gram variable rod
Add KOH = whiff test
Tx - metronidazole, clindamycin

223

MOA of edema factor

Adenylate cyclase that increases intracellular cAMP -> PMN and macrophage dysfunction and tissue edema
Found in Bacillus anthracis and Bordetella pertusis

224

Infant presents with winter cough and difficulty breathing. Diffuse expiratory wheezes and scattered rales throughout

RSV

225

How do we prevent vertical transmission of HIV1?

Antiretroviral therapy
All HIV + moms should take ART regardless of CD4 count or viral load
2 NRTs + protease inhibitor/NNRT/integrase
Infants will generally receive several weeks of zidovudine

226

Group A strep is resistant to phagocytic killing when placed in fresh human blood. This could be overcome by adding Ab against?

Protein M - major virulence factor, inhibits phagocytosis and activation of complement
NOT:
Streptolysin O - lyses RBCs
Steptokinin - catalyzes plasminogen to plasmin to facilitate strep spread

227

A medium containing vancomycin, colistin, nystatin, and trimethoprim favors growth of?

Neisseria gonorrhoeae
Thayer-Martin selective medium
Chocolate agar + Vanco, colistin, nystatin, trimethoprim

228

Which cause of gastroenteritis has a small infectious dose?

Shigella flexneri
Also entamoeba and Giardia

229

Most important factor in pathogenesis of Shigella?

Mucosal invasion
Non-motile, non-lactose fermenting organism
Mucosal invasion of M cells that overlie Peyer's patches

230

Pt develops parotitis following intubation. What serum marker would be useful in dx?

Elevated Amylase (nut lipase WNL to rule out pancreatitis)
Typically in post op or post intubated elderly pts.
Usually S. aureus

231

Pneumonia + intranuclear cytoplasmic inclusion bodies in a post lung transplant pt?

CMV
enveloped dsDNA virus
Owl's eyes

232

How do you treat C. diptheriae?

Passive immunization

233

aedes aegypti transmit which 2 diseases?

Dengue Fever - retrorbital pain + joint and muscle pain
Chikungunya - Flu like + polyarthralgias + rash

234

Filamentous bacteria with pulmonary, skin, and CNS syx?

Nocardia

235

Pt with flu like illness, retroorbital headace with recent exposure to animal waste (farm animals)

Coxiella burnetii
Q fever

236

HSV1 acquires acyclovir resistance from co culture with HSV 2 and the progeny continue to be resistant. What is the mechanism?

Recombination
Gene exchange through cross over
Can't be phenotypic mixing because the progeny would have lost resistance

237

A strain of M. TB has decreased activity of intracellular catalase peroxidase. It would be resistant to?

Isoniazid
INH prevents mycolic acid synthesis and INH must be processed by mycobacterial catalase peroxidase for the drug to be activated within the bacteria