Old Micro Written Exams 2 Flashcards
1
Q
- Hematologic findings in blood smear with the following conditions:
a. Babesiosis
b. Diphyllobothrium
c. Ehrlichia
d. EBV
A
a. Babesiosis – Intracellular and extracellular small ring forms, maltese cross conformation
b. Diphyllobothrium – Megaloblastic anemia (Vitamin B12 deficiency)
c. Ehrlichia – detection of morulae in the cytoplasm of infected monocytes
d. EBV – Reactive (atypical) lymphocytosis
2
Q
- Name 2 quality indicators each in the pre-analytic, analytic, and post-analytic phases.
A
Pre-Analytical: Blood culture volumes, Specimen mislabelling , Blood culture contamination rates, Sample delivery times
Analytical: Time to reporting of stat Gram Stains, QC performed accurately and on schedule, Sample contamination
Post-Analytical: Correct antibiotics given based on susceptibility report, Report delivery turn around times, Critical result reporting, proportion of corrected reports
3
Q
- Your lab wants to replace GC culture with urinary PCR for women. Name 3 disadvantages or limitations.
A
- Unable to perform susceptibility
- High costs
- Carryover contamination risk
- High QC requirements
- Assays are susceptible to inhibition from substances found in the urine
- Cross reaction with Neisseria lactamica (QMPLS document)
4
Q
- Name 2 disadvantages for Chlamydia PCR.
A
- Can not use for medico-legical purposes
2. Nongenital specimens have not been FDA approved
5
Q
- Safety for PGFE: what precaution should personnel take in handling the gel? What document should always accompany this product? What safety procedure must be done while taking the UV picture?
A
Always wear gloves when handling the gel due to the Ethidium Bromide.
An MSDS should always be with this product
When taking the UV picture make sure to wear protective eye wear
UV source should be contained
6
Q
Kidney transplant with increasing creatinine. There are decoy cells in urine. What infection do you suspect? What are 2 test specimens to submit?
A
BK Virus
- Urine and serum for PCR for BK Virus
- Renal Biopsy to detect cytopathic effect and positive immunohistochemistry staining for SV40 large T antigen
7
Q
- You suspect coccidiomycosis. Name two method to confirm.
A
Culture
Histopatholgy of biopsy
Serology
Antigen Testing
EIA for IgM and IgG are the most sensitive screening tests. The immunodiffusion tests are less sensitive but more specific.
Note: Gram stain does not stain the spherules. They can be seen with a saline or KOH wet mount, Calcoflour staining, or PAP stain. For tissue can use H&E, PAS or Silver Staining.
GenProbe has an antigen detection kit that can be used from cultures and detects C. immitans specific DNA.
8
Q
- Coxiella serology: phase I antibodies 1/1600; phase II 1/50. Interpret.
A
Chronic Q fever Infection
9
Q
- Name 3 yeast that are urease +.
A
- Cryptococcus
- Rhodotorula
- Trichosporon
- Malessezia
- Candida krusei
- Candidia lipolytica
10
Q
- Women with parvovirus B19 IgM +. 3 interpretations. What should you do next?
A
1) Acute infection (IgM present in 7-10 days)
2) Infection in the past 3 months (IgM lasts 2-3 months, but can last up to 6 months)
3) False positive IgM (due to Rheumatoid Factor)
Determine if pregnant
Check IgG Ab, if acute may have negative IgG, if 3 months ago IgG should be present. Can test IgG avidity to help distinguish between recent and past infections. (High avidity = past infection, low avidity = recent). Not commercially available.
Can test blood for Parvovirus DNA to determine possible infection via NAT (PCR).
Order CBC to assess for aplastic anemia.
Can also repeat serology to determine if there was
11
Q
- Fusiform GNB in blood in splenectomised patient. What is the likely organism? Name another organism with similar gram stain morphology.
A
Capnocytophaga
Fusobacterium nucleatum
Leptotricia buccalis
12
Q
- Contact lens wearer went swimming w/ his contacts on and develops keratitis.
a. What is the likely diagnosis?
b. What two stains should be done on the corneal
c. What is the best culture medium?
A
Acanthaomeba keratitis
b. What two stains should be done on the corneal scraping? Trichrome Modified Fields Stain Hemacolor Stain Fluorescent Dye Calcoflour Geimsa
c. What is the best culture medium?
Create a lawn of E.Coli or Enterobacter aerogenes on a petri dish with 1.5% Difco agar made with Page’s amoeba saline. This is a non nutrient media. Then inoculate the specimen
13
Q
Because of several years of high-level West Nile circulation, your lab wants to institute an IgM test. What are 2 disadvantages? What test do you use for detecting WNV in organs?
A
Disadvantages: 1) Cross reaction with other Flaviviridae viruses – need to follow a positive IgM with a neutralization test to determine which virus is causing the positive IgM
2) West Nile Virus IgM can remain positive for up to 2 years
after infection
3) IgM may be negative very early on in infection
Advantages: Short period of viremia, so hard to detect early. IgM is present within 3-5 days of the illness and appears early in the CSF (2-3 days).
Diagnosis in Organs = PCR
14
Q
- Patient on ganciclovir for CMV has persistant positive antigenemia. Name 2 resistance mechanisms for gancyclovir to CMV. Name 2 tests for susceptibility testing of CMV against ganciclovir. What 2 antivirals can you use if ganciclovir is resistant?
A
Resistance Mechanisms:
- Alternation in phosphorylation of gancyclovir, therefore the drug is not rendered active (UL97 - phosophotransferase gene mutation)
- Alteration in the viral DNA polymerase gene (UL54) : Also R to foscarnet
Susceptibility Testing:
- Phenotypic Assay – measures the ability of CMV to grow in cell culture in the prescence of various concentrations of antiviral drugs
- Genotypic Assay – to detect the known resistance genes via PCR and sequencing, or probes
Antivirals:
- Cidofovir
- Foscarnet
15
Q
- For rapid-growing mycobacteria, list 4 antibiotics found in the antibiogram.
A
- Clarithromycin
- Doxycycline
- Amikacin
- Cefoxitin
- Linezolid
- TMP-SMX
- Imipenem
- Moxifloxacin
- Tobramycin
- Ciprofloxacin
16
Q
- African with general deterioration. Negative HIV serology 6 months ago. Returns from trip to Africa. Rapid test HIV negative, but ELISA pos, WB indeterminate at reference lab.
a. What are two possible explanations?
A
1) HIV2 infection (will be negative on rapid test)
2) Early HIV1 infection with false negative rapid HIV result
3) Group O HIV1 infection
4) Group M, non B infection
5) False positive ELISA due to immune complexes (this is a problem with the p24 antigen ELISAs, not the 3rd generation tests but maybe the 4th generation tests. That’s why the positives have to be confirmed with NAAT or Western blot)
17
Q
- African with general deterioration. Negative HIV serology 6 months ago. Returns from trip to Africa. Rapid test HIV negative, but ELISA pos, WB indeterminate at reference lab.
b. What 2 tests should you do to supplement?
A
1) HIV1 NAT
2) HIV2 NAT
3) HIV2 specific Western Blot
4) Repeat the ELISA
5) Use an IFA to resolve the discrepant Western Blot result
18
Q
- Man with chronic cough. Dog was diagnosed with canine pertussis. A throat culture is growing on Bordet Gengou, coryneform that is oxidase positive.
a. What is the most likely etiologic agent?
b. Name 3 phenotypic tests for this bacterium.
c. What biosafety containment level is needed?
A
Bordetella bronchoseptica
b. Name 3 phenotypic tests for this bacterium.
1) Catalase positive
2) Motility positive
3) Reduction of Nitrate positive
4) Urea Reduction Positive
c. What biosafety containment level is needed?
Biosafety Containment Level 2
19
Q
- Differentiate between B anthracis & cereus.
A
hemolysis
colonial morphology
motility
β-lactamase
20
Q
Hunter gets sick. Blood cultures show small GNCB that is oxidase -, catalase weak +, urea -, only growing on chocolate.
a. What is the diagnosis?
b. What special nutrient does this bacterium need?
c. What 4 antibiotics does a reference lab need to test for?
A
Tuleremia (Fransicella tularensis) b. What special nutrient does this bacterium need? Cysteine c. What 4 antibiotics does a reference lab need to test for? 1) Gentamicin 2) Doxycycline 3) Ciprofloxacin 4) Chloramphenicol
21
Q
- What are 4 CLSI criteria for cumulative antibiotic susceptibility reports?
A
1) Data verification – only report final, verified results
2) Only report one isolate of the same species per patient during the time frame of the report
3) Data should be analysed at least annually
4) Include only species with testing data for >=30 isolates
5) Include only diagnostic isolates (not surveillance)
6) Include only routinely tested antimicrobial agents
22
Q
- POW from world war II in Japan complains of itchy skin, description of larva currens on the trunk. What is the diagnosis? Name 2 methods for finding this parasite in the stool?
A
Strongyloides stercoralis
To find the parasite in the stool:
1) Agar plate culture – look for the larvae to drag bacteria around the plate, then flood with saline and centrifuge to look for the rhabdiform larvae
2) Harada-Mori technique – feces on a filter paper dipped in water, the parasites migrate to the water and can then be detected via microscopy
3) Microscopy of feces (low sensitivity) after concentration
23
Q
- Your technician drops a blood culture bottle growing M. tuberculosis. What are the 5 steps to take in chronological order?
A
- Hold your breath (if you are not already wearing PPE)
- Put on appropriate PPE
- Turn off centrifuges?
- Turn on BSC?
- Contain the spill so it doesn’t continue to spread
- Exit the area safely and wait 30 minutes until returning
24
Q
- How do you confirm the presence of an ESBL by broth dilution w/MIC? Name 4 bacteria that should be screened for ESBL if found in blood culture.
A
Using CAMHB agar do MIC testing of Ceftazidime and Cefotaxime both with and without Clavulanate. A ≥3 twofold dilution concentration decrease in MIC in either agent in combination with clavulanate compared to either agent alone is positive for ESBL.
Example: CAZ MIC =8, CAZ/CV MIC = 1 would be an ESBL
25
4 bacteria to screen for ESBL
i. Klebsiella pneumonia
ii. Klebsiella oxytoca
iii. Proteus mirabilis
iv. E. coli
26
38. A woman is 12 wks pregnant. Toxo serology done at 0 & 12 wks show IgM & IgG positive
a. Give 2 possible explanations.
b. What are 2 other serologic tests that would aid the
c. If a PCR will be needed, what specimen should be sent?
a. Give 2 possible explanations.
1) Infection with toxoplasmosis during the past year
2) Acute infection during pregnancy
3) False positive IgM
b. What are 2 other serologic tests that would aid the diagnosis?
1) IgG avidity test – High avidity = 3-5 months, most helpful in the first 16 weeks. Low avidity can persist for many weeks.
2) Toxoplasma specific IgA antibody (usually falls faster than the IgM)
3) Toxoplasma specific IgE antibody serology (falls faster than IgA and IgM, more acute)
c. If a PCR will be needed, what specimen should be sent?
Amniotic fluid
27
39. Name 2 GNB anaerobes that are resistant to kanamycin & do not grow on BBE.
1) Prevotella species (RRV) KVC
| 2) Porphyromonas species (KR, VS, CR, Will not grow on bile)
28
40. Child with VP shunt presents with his fifth episode of meningitis. GPC, cat -, PYR -, LAP -, vanco R.
a. What is the species?
b. Name 3 other catalase-negative GPC with intrinsic vanco resistance.
```
a. What is the species?
Leuconostoc species (Also could be Weisiella)??
```
b. Name 3 other catalase-negative GPC with intrinsic vanco resistance.
Pediococcus
Weisiella
Enterococcus gallinarum
29
41. Explain 2 methods of sequencing.
1. Dideoxynucleotide Chain Termination –
Decreased quality after 700-900 bases
First 50 bases are not reliable
Sanger method
2. Pyrosequencing – luminometric detection of pyrophosphate generated during DNA synthesis. (New Generation Sequencing)
30
a. Name 2 staphylococci that are PYR +.
```
Staphylococcus lugdunensis
Stapylococcus schleferi
Staphylococcus hemolyticus
Staphylococcus intermedius/pseudointermedius
Staphylococcus carnosus
```
31
b. Which staphylococcus is PYR + and ODC +? What oxacillin breakpoint is used? This particular bacterium is sensitive to cefoxitin - what is the treatment?
Staphylococcus lugdunensis
Use the break point for Staphylococcus aureus (MIC <=2) but if using disk testing oxacillin disk testing is not reliable and cefoxitin should be used as a surrogate.
If sensitive to cefoxitin can use Cloxacilin to treat.
32
43. Name one dermatophyte that does not affect the hair?
1) Microsporum cookie
| 2) Epdiermophyton floccosum
33
44. Name 2 methods for finding cryptosporidium in the stool.
1) Modified Acid Fast Staining
2) Wet mount
3) DFA
4) Stool EIA Antigen Test
34
45. Name two tests to distinguish Gram + from Gram - anaerobes, other than the KOH/string test.
1) GramSure? May fail to give expected results
| 2) Vancomycin susceptibility
35
46. Gastroenteritis outbreak in geriatric ward, on EM, you see a particle that is 32 nm in diameter. What is the most likely agent? What is the most sensitive test to diagnose it?
Small Round Virus
Norovirus
PCR is the most sensitive test
36
47. Name 2 phenotypic tests to differentiate Nocardia from Mycobacteria.
1) Kinyoun Stain (Nocardia NEG, Mycobacteria POS)
2) Aerial Hyphae (Nocardia POS, Mycobacteria NEG) ?? Variable for Mycobacteria….
3) ? Branching on gram stain
37
48. Name 2 methods to screen for high level gentamicin resistance in Enterococcus, and include media, antibiotic concentrations, incubation conditions, and interpretation.
1) Disk Diffusion – Muiller Hinton Agar, Gentamicin 120 ug disk, Incubate in Ambient Air, 35 +/- 2 degrees Celsius for 16-18 hours. 6 mm = Resistant, ≥10 mm = Susceptible, 7-9mm = Indeterminate. If Resistant it is not synergistic with a cell wall agent, if Susceptible there is synergy with a cell wall active agent. If inconclusive do Broth Microdilution or Agar Dilution.
2) Broth Microdilution – BHI broth, Gentamicin Concentration 500 ug/mL, Incubate in Ambient Air, 35 +/-2 degrees for 24 hours. 0.5 MacFarland Any growth is Resistant.
3) Agar Dilution – BHI agar, Gentamicin concentration 500 ug/mL, Spot 10ul of a 0.5 MacFarland onto agar surface. Incubate in Ambient Air, 35 +/-2 degrees x 24 hours. >1 colony = Resistant.
38
1. Name 4 indications for measles vaccination.
1. Children aged 12 months – 17 years (Routine childhood immunization)
2. Adults born after 1970 without documented vaccine receipt immunity to measles virus
3. Health care workers without 2 doses of measles vaccine, or no evidence of immunity, or no evidence of previous measles virus infection
4. Military personnel who do not have documentation of 2 doses of measles vaccine, no immunity to measles, or do not have documentation of laboratory confirmed measles infection
5. Travellers to destinations outside of North America
39
Contraindications for Measles Vaccine:
1. Persons with previous anaphylaxis to any component of the vaccine
2. Persons with impaired immune function, including primary and secondary immune disorders
3. Pregnancy
4. Individuals with active, untreated tuberculosis (Only in PHAC CIG)
40
2. Name 3 indications for IGRA.
1. Persons previously vaccinated with BCG vaccine
2. Persons unlikely to return for reading of a TST
3. In place of TST when testing indicated
4. In combination with TST if risk of infection progression to disease and poor likelihood of poor outcome do both
5. Children and suspect active TB can use TST and IGRA to support diagnosis
6. Skin conditions prohibiting TST testing
41
3. Teen with headache, fever and nuchal rigidity. LP shows gram negative diplococci.
a. 3 actions to be undertaken immediately?
1. Start empiric antibiotics to cover Neisseria meningitits (Ceftriaxone 2 g IV q12h)
2. Place the patient on Droplet precautions until 24 hours after antimicrobial therapy
3. Notify public health of a presumptive case of N. meningitidis
42
b. Meningococcus is confirmed; 2 subsequent actions or modifications?
1) Switch antimicrobial therapy to Penicillin G 4 MU IV q4 h for 7 days if susceptible
2) Initiate antimicrobial prophylaxsis and vaccination for close contacts of the patient
i. Prophylaxis (adults) =
Ceftriaxone 250 mg IM x 1 OR
Ciprfloxacin 500 mg PO x 1 OR
Rifampin 600 mg po q12h x 2 days
3) Give vaccine to contacts
43
c. List 4 indications of vaccination against meningococcus.
1) All children and young adults <=24 years old
2) Laboratory workers potentially exposed to N. meningitidis
3) Travellers to areas where vaccine is recommended
4) Persons with functional or anatomical asplenia
5) Military personnel during training
6) Persons with complement deficiencies
44
4. Name 6 treatment options for MRSA
```
Vancomyin
Linezolid
Daptomycin
Tigecycline
Septra
Clindamycin
Telavancin
```
45
Ceftaroline has been approved for what indication?
SSTI
| CAP
46
7. Fever, pancytopenia, and hypergammaglobulinemia from Northern India. Weight loss, HSM, adenopathy & thrombocytopenia. What is the diagnosis, what tests should you do, and what is the treatment?
```
Viseral leishmaniasis
Bone marrow biopsy
Splenic aspirate (gold standard)
Pathology
Culture and PCR for species
Antigen test K39 (Mayo)
Treatment = Amphotericin B
miltefosone, antimony, paromomycin
```
47
10. Chronic meningitis in HIV. Two specific tests to be requested?
```
Crytococcal Ag test from CSF, India ink, silver stain, culture
Culture CSF for mycobacteria (TB)
Syphilis (CSF VDRL)
HSV
Nocardia
```
48
11. Name 4 indications for endocarditis prophylaxis, and list 2 oral medications that can be used. What if patient has a non-anaphylactic allergy to penicillin? Include dosage.
1. Patients with prior IE, prosthetic valves, or prosthetic material used to repair a valve undergoing a dental procedure that involves manipulation of gingival tissue, periapical tooth region, or perforation of oral mucous (not for routine cleanings)
2. Patients with prior IE, prosthetic valves, or prosthetic material used to repair a valve undergoing respiratory tract mucosa incision or biopsy.
3. GU or GI procedure if there is active infection
2 oral medications = Amoxicillin or Cephalexin
Non Anaphylaxis Penicillin Allergy = Cephalexin 2 g in one single dose 30-60 min prior to procedure
Anaphylaxis to Penicillin = Clindamycin or Azithromycin or Clarithromycin
49
12. Enterococcus faecalis endocarditis. Penicillin MIC of 2, gentamicin MIC>500. Name treatment and duration.
Treatment =
Ampicillin 2 g IV q4h x 6 weeks PLUS
Streptomycin 15 mg/kg IV divided in 2 doses x 6 weeks
CLSI Penicillin breakpoints for Enterococcus = ≤8, -, ≥16. Therefore it’s Susceptible to penicillin.
CLSI screening for HLAR uses an MIC of 500 as the breakpoint, >500 is Resistant, ≤500 is susceptible.
Therefore this isolate is Susceptible to Penicillin and resistant to Gentamycin.
50
13. Treatment for HSV encephalitis in newborn. Dosage and duration.
Acyclovir 60 mg/kg per day IV divided q8h x 21 days. Some do repeat LP then and if positive continue treatment and weekly LPs until HSV DNA is not detected.
51
14. Case of gout crisis in a patient recently started on TB meds including PZA. What 2 things would you do?
1) Discontinue PZA
2) Treat gout with NSAID therapy
3) Start a fluoroquinolone (moxifloxacin)?
52
15. 65M w/ previous history of VZV wants Zostivax.
a. What is the efficacy?
b. This patient is on Valtrex. Do you give the vaccine? Justify.
c. Patient now wants pneumococcal vaccine. Can you give it at the same time?
a. What is the efficacy?
51% for incidence of herpes zoster, and 66% for post herpatic neuralgia
b. This patient is on Valtrex. Do you give the vaccine? Justify.
No. It is a live vaccine and Valtrex will decrease the efficacy of the vaccine. Should not take Valtrex for 24 hours before vaccine and 14 days after.
c. Patient now wants pneumococcal vaccine. Can you give it at the same time?
Yes
53
16. Woman exposed to VZV during 1st trimester.
| a. What is her risk for transmission to fetus?
0.4% for first trimester
2% for second trimester
Congenital varicella syndrome
54
b. What is the post-exposure treatment for VZV exposure in pregnancy?
VZIG (or VariZIG): Varicella specific immunoglobulin as soon as possible after the exposure and up to 10 days post exposure
55
17. Name 4 clinical features of congenital VZV.
Congenital Varicella Syndrome:
Cutaneous scars in dermatomal pattern
Neurological abnormalities (MR, microcephaly, hydrocephalus, Sz, Horner’s syndrome)
Ocular abnormalities (optic nerve atrophy, cataracts, chorioretinitis, microophthalmus, nystagmus)
Limb abnormalities (hypoplasia, atrophy, paresis)
GI abnormalities (GERD, stenotic bowel)
Low birth weight
56
19. Name numerator and denominator for surveillance of VAP.
```
Numerator = Number of patients undergoing mechanical ventilation who have VAP (NHSN definition)
Denominator = Number of ventilator days
```
57
20. Woman from Niger with chronic pruritus, dermatitis, and skin nodule on iliac crest. What is the diagnosis, method to confirm diagnosis, and treatment?
Onchocerciasis
Skin snip then incubate in saline for 24 hours and look for motile microfilaria
Treatment = Ivermectin
First have to rule out Loa Loa because if they have a high burden of LoaLoa microfilarie can precipitate an encephalopathy. If they were to have high levels of Loa Loa may have to do plasmaphoresis first. The treatment for Loa Loa is DEC but you can’t use that if they have oncocerciasis because they can go blind (kills the adult worm).
Ivermectin only kills the microfilaria
Wolbachia treated at the same time or prior with Doxycycline. Effective at reducing microfilarial production by adult worms.
Have to retreat until the adults eventually die off (10-14 years)
Onchocerciasis can cause blindness.
58
21. List 6 manifestations of chronic Lyme disease. What is the treatment of CNS Lyme?
1) Fatigue
2) Headache
3) Arthralgias
4) Myalgias
5) Cognitive difficulties
6) Acrodermatitis chronica trophicans
7) Radiculopathy
8) Keratitis
Treatment for CNS Lyme = Ceftriaxone 2 g IV daily 2-4 weeks
59
22. List 2 treatment options for an HIV patient with PCP, but with allergy to Septra. What are 3 options for prophylaxis? What is an indication to add steroids?
Treatment:
1) Pentamidine
2) Clindamycin + Primaquine
3) Dapsone + Trimethoprim
4) Atovaquone
Prophylaxis:
1) Pentamidine 300 mg monthly aerosolized via nebulizer
2) Atovaquone 750 mg po bid
3) Dapsone 100 mg po daily (monitor closely for possible hypersensitivity)
Steroids if moderate to severe disease (Pa)O2 35 mmHg
60
23. List 6 organisms that can cause culture-negative endocarditis.
1) Coxiella burnetii
2) Bartonella species
3) Trpheryma whippelii
4) Chlamydia species
5) Legionella species
6) Brucella species
7) Non-Candida fungus
8) Rickettsia
61
24. 53F w/ fever & pulmonary infiltrate. Sputum ZN - but culture grows MAC. Do you treat?
24. 53F w/ fever & pulmonary infiltrate. Sputum ZN - but culture grows MAC. Do you treat?
62
Treatment for MAC?
Macrolide (Clarithro 500 BID, or Azithro 250 Daily)
+ Ethambutol 15 mg/kg
+ Rifampin 600 mg daily or Rifabutin 300 mg daily
+/- Aminogylcoside (Streptomycin or Amikacin intermittently)
Duration = 12 months after cultures are negative
63
25. 32 y.o. Nigerian male with spastic paraparesis, but normal bladder & anal function. Name 1 parasitic cause, 2 bacterial causes, and 3 viral causes.
Parasites: Toxocara canis, Diphylobothrium latum (Vit B12 deficiency)
Bacterial: Mycoplasma, Borrellia burgdorferi, Treponema pallidum
Viral: HTLV1, HIV, CMV, HSV, EBV
64
26. 42 M w/ dementia for last 6 months. LP shows slightly elevated protein, MRI shows elevated signal on T2 in the thalamus. What is the most likely diagnosis? List 2 tests that can be done antemortem. Name 2 clinical forms of this disease.
Pulvnar sign
CJD (Creutzfeldt-Jakob Disease)
Tests:
1) Demonstatration of abnormal prion protein forms on brain tissue via immunohisotchemistury
2) Western immunoblot to analyze protease resistant form of prion protein
Clinical forms:
1) Sporadic CJD – older, rapid progression
2) Variant CJD – younger, slower progression (6-12 months), more psychiatric manifestations
Biopsy shows vaculation of neutrophils, reactive gliosis, neuronal loss = Spongioform change
2 known familial forms: FFI, GSG
Kuru infection from canabolism
65
27. 22M presents w/history of multiple sexual partners & chancre on black base. Diagnosed as primary syphilis. What is the treatment & duration?
a. The patient calls you with a fever, myalgias, and chills the next day. Why?
b. What contact tracing needs to be done for him, and how far back must it go?
Benzathine Penicillin G 2.4 Millon Units IM X 1
a. The patient calls you with a fever, myalgias, and chills the next day. Why?
Jarisch-Herxheimer reaction
b. What contact tracing needs to be done for him, and how far back must it go?
All sexual partners in the past 90 days (Mandells)
66
28. Name the pathogen that causes:
a. donovanosis/granuloma inguinale
b. chancroid
c. LGV
d. condyloma acuminate
e. condyloma lata
f. molluscum contagiosum
28. Name the pathogen that causes:
a. donovanosis/granuloma inguinale – Klebsiella granulomatis
b. chancroid – Haemophilus ducreyi
c. LGV – Chlamydia tracomatis (serovars L1-L3)
d. condyloma acuminate – Human papilloma virus
e. condyloma lata – Treponema pallidum
f. molluscum contagiosum – Poxvirus
67
29. 20F w/otitis treated w/clavulin develops a fever, decreased mental status & CT head shows jugular thrombosis. No intracerebral mass, but there is meningeal enhancement. Blood cultures are+ for polymorphic anaerobic GNB. CSF culture is negative. What is the organism? What other test must be done? What is your treatment?
Organism = Fusobacterium necrophorum
Other Tests = Chest Xray to look for pulmonary emboli? (Not sure…)
Treatment = PipTazo
68
30. Name 2 infectious causes of congenital cataracts.
1) CMV
2) Rubella
3) Toxoplasmosis
4) HSV
5) Syphilis
6) Varicella
69
31. For Parvovirus B19, list 4 clinical syndromes.
1) Erythema infectiousum (EI)
2) Transient Aplastic Crisis (TAC)
3) Pure Red Cell Aplasia (PRCA)
4) Fetal Hydrops
5) Glove and Stocking Papular Purpuric Syndrome
6) Polyarthropathy
70
32. Patient post-allogeneic HSCT, on treatment for GVHD & taking voriconazole for aspergillosis prevention. Develops temperature, purpura on legs, & new lung infiltrates.
a. What are the 2 most likely diagnostic hypotheses?
b. List 4 tests to do.
c. What antimicrobials should you give?
a. What are the 2 most likely diagnostic hypotheses?
1) Infection with a fungus resistant to Voriconazole (Zygomyces)
2) Bacteremia with sepsis
```
b. List 4 tests to do.
Blood cultures x 2 sets
Bronchoscopy for bacteriology, fungal, viral, and mycobacterial culture
Tissue biopsy of skin lesions
CT Scan
```
c. What antimicrobials should you give?
Amphotericin B +/- posaconazole
Broad spectrum antibiotics
71
33. Giardia treated with Flagyl for 10d has recurrence. Symptoms & stool + 2 wks later.
a. What are 2 possible explanations?
b. What are 2 other possible treatments?
```
a. What are 2 possible explanations?
Reinfection
Failed treatment with Flagyl
Post infectious irritable bowel
Immunodeficiency leads to chronicity (IBD)
```
b. What are 2 other possible treatments?
Albendazole 400 mg po daily x 5 days
Paromomycin 500 mg po TID x 5-10 days
Tinidazole
72
34. What is the treatment for Dientamoeba fragilis? Name 2 other parasitic infections commonly found in daycare instititutions.
Treatment = Metronidazole 500-750 mg po TID x 10 days
OR Paromomycin 25-35 mg/kg divided in 3 doses PO x 7 days
Iodoquinol
Treat when Dientamoeba fragilis is the only pathogen in the stool with diarrhea or abdominal pain for 1 week.
Only see the trophozoite form. No flagella, 1 or 2 nuclei.
Can have peripheral eosinophilia with D. fragilis.
2 other parasites in daycares:
1) Giardia lamblia
2) Cryptosporidium
73
35. Macaque bite from monkey just delivered from Morocco. Name 4 infections that are preventable by prophylaxis.
1) Rabies
2) Herpes B (Acyclovir/Valacyclovir)
3) Bacterial infection
4) Clostridium tetanus
74
a. Name 2 ways to measure response to treatment for HCV.
Viral DNA
| Liver function tests?
75
b. The patient has genotype 1A. What is the treatment & duration? This patient is HIV/HCV co-infected
Ledipasvir + Sofosbuvir x 12 weeks OR (8 weeks if no cirrhosis)
Simepravir + Sofosbuvir x 24 weeks (12 weeks if no cirrhosis)
Don’t use Sofosbuvir + Ribavirin: It did worse in the coinfected patients
76
c. What is the test done at the start of HCV treatment that predicts good outcome?
IL28 polymorphism
77
d. What 2 ARV are contraindicated during HCV treatment & why?
1) Ritonavir boosted Tipanivir – Decreases Sofosbuvir levels
2) Tenofovir – Uncertain safety of increased tenofovir levels
3) Didanosine with ribavirin
4) Atazanvir with ritonavir (jaundice)
78
37. Name 4 indications for 2nd dose of MMR to prevent mumps.
1) Routine immunization of all children
2) Health care workers born after 1970
3) Military personnel born after 1970
4) Students in Secondary or Post Secondary Institutions
5) Outbreak control
6) Travel outside of North America
79
38. 22M with clinical picture of mumps.
a. Name 3 tests to confirm the diagnosis.
b. What are 4 possible complications?
c. How long can it be isolated for?
a. Name 3 tests to confirm the diagnosis.
Positive IgM serology with an epidemiological link
4 fold rise in IgG between acute and convalescent serology
Virus isolation from culture or PCR from buccal swab
b. What are 4 possible complications?
1) Orchitis
2) Oophritis
3) Aseptic meningitis
4) Deafness
5) Encephalitis
6) Pancreatitis
7) Sailatasia
8) Epididymitis
c. How long can it be isolated for?
14 days after onset of symptoms
80
39. Inuit child in respiratory distress, fever, throat culture pos suspicious for C. diphtheriae
a. What agar to use?
b. What 3 actions to take immediately, in addition to antibiotic treatment?
c. Once ID is confirmed, what other 2 actions to take?
d. What is the best treatment?
Tinsdale Agar
b. What 3 actions to take immediately, in addition to antibiotic treatment?
1) Diptheria antitoxin administration
2) Place patient on respiratory droplet precautions until 2 cultures 24 hours apart are negative
3) Intubate if airway concerns exist or may arise
c. Once ID is confirmed, what other 2 actions to take?
1) Notify public health (now or earlier?)
2) Treat close contacts with penicillin or erythromycin and offer unvaccinatinated patients vaccine
d. What is the best treatment?
Erythromycin 500 mg po QID x 14 days
(Penicillin is also good)
81
40. List 6 genera of fungi that are resistant to caspofungin.
1) Cryptococcus
2) Histoplasma
3) Blastomyces
4) Coccidioides
5) Sporothrix
6) Scedosporium
7) Trichosporon
8) Mucor
9) Fusarium
10) Paracoccidioides
82
41. Name 4 mechanisms of colonization of central catheters.
1) Hematogenous spread
2) Skin organisms
3) Instillation of infected material
4) Colonized hub
83
42. In an HIV treatment naïve patient, name 2 preferred treatments (one with PI & one without) that are dosed once daily.
1) Atripla – Efavrinez/Emtricitabine/Tenofovir (no PI)
2) Stribild – Elvitegravir/Cobistat/Emtricitabine/Tenofovir (No PI)
3) Complera – Rilpilverine/Emtricibaine/Tenofovir (No PI)
4) Triumeq – Dolutegravir/Abacavir/Lamivudine
5) Dolutegravir + Truvada (Emtricitabine/Tenofovir)
6) Darunavir/Ritonavir/Emtricitabine/Tenofovir (Has a PI)
7) Atazanavir/Ritonavir/Emtricitabine/Tenofovir (Has a PI)
84
43. EBV: list 4 related cancers.
1) Burkitt’s Lymphoma
2) Nasopharyngeal Carcinoma
3) T Cell Lymphoma
4) Hodkin’s Lymphoma
5) PTLD – post transplant lymphoproliferative disease
6) Primary CNS Lymphoma
7) Primary Effusion Lymphoma
85
44. 50 y.o. diabetic with sinusitis progressing to proptosis, dark nasal discharge & with a black spot on his palate. What is the etiology, and what are 3 interventions to take?
Zygomyces
3 interventions:
1) Start Amphotericin B (5-10 mg/kg IV daily)
2) Consult surgery re: Surgical debridement
3) Correct hyperglycemia
86
45. Pneumonia secondary to nosocomial Legionella in 2 patients.
a. What are 2 treatment options?
b. What are 2 interventions to stop transmission?
a. What are 2 treatment options?
Azithromycin
Levofloxacin
b. What are 2 interventions to stop transmission?
Heat water to 70 degrees celcius and flush water system for 30 minutes
Copper-Silver ionization units
Hyperchlorination
87
46. Name 2 contra-indications for flu vaccine.
1) Severe allergy to any components of the vaccine
2) Previous Guillain-Barre Syndrome within 6 weeks of influenza vaccine
3) Less than 6 months of age
88
47. Name 2 indications to look for & treat an asymptomatic bacteruria.
1) Pregnancy
2) Prior to Transurethral Resection of the Prostate (TURP)
3) Prior to undergoing an urological procedure with anticipated mucosal bleeding
89
2. S. aureus grows on oxacillin screen, and R to cefoxitin. Testing shows that it is mecA -.
a. What is the resistance mechanism?
b. What else should be tested?
1) Resistance mechanism is hyperproduction of Beta lactamase (BORSA)
2) mecC in Europe, not yet in Canada, not detected by mecA PBP or mecA PCR. mecC is an altered PBP but is different from the one caused by mecA
b. What else should be tested?
1) B – lactamase – would show that it has a beta lactamase. Could do an oxacillin MIC
Other things we came up with….
2) Test for PBP2a with latex agglutination and an anti-PBP2a monoclonal antibody – Baldwin said no for this because if it’s mecA negative then the PBP2a would not be helpful. But it could be helpful if the mecA PCR was false negative to see if it’s an MRSA. The PBP2a test will also be negative for mecC as it produces a different PBP2a(mecC).
3) Inhibitor test with Oxicillin and a B-lactamase inhibitor – Baldwin thought this was reasonable but didn’t know if the test exists
4) Look for mecC – specific mecC primers for PCR
90
3. Cervical swab received, with a request for anaerobes. What 2 things you should do?
1) Inform the physician that the specimen type is inappropriate for anaerobic culture due to the large number of anaerobes present as normal vaginal flora
2) If an IUD was present can look for actinomyces on a gram stain
91
4. Table: 3 distinguishing characteristics of endotoxins vs. exotoxins.
```
Exotoxin:
Released from cell
Protein
Produced by gram Pos and Neg
High antigenicity
```
```
Endotoxins:
Integral part of cell wall
Lipid A of the LPS
Only on gram Neg
Low antigenicity
```
92
6. For each organism & drug combination, list one susceptibility testing method with the media and the incubation conditions:
a. N. gonorrhoeae and ciprofloxacin
b. Aeromonas in blood
c. H. influenzae in CSF
d. Enterococcus screening
a. N. gonorrhoeae and ciprofloxacin – Agar dilution or Disk Diffusion – GC agar base and 1% defined growth supplement, 36 +/-1 degree, CO2, 20-24 hours
b. Aeromonas in blood – Disk Diffusion – Muiller Hinton Agar – 35 degrees, ambient air, 16-18 hours
c. H. influenzae in CSF – Disk Diffusion with Haemophilus Test Media, 35 degrees CO2, 16-18 hours
d. Enterococcus screening – Agar Dilution BHI agar with 6 ug/mL of Vancomycin, 35 +/-2 degrees, ambient air, 24 hours
93
7. List 3 yeast that are urease +, other than Cryptococcus. Name a colour indicator for urease.
1) Trichosporon
2) Rhoduroturula
3) Sporobolomyces
4) Candida krusei
Color indicator for urease = Phenol red
94
List 3 causes of a false + cryptococcal antigen.
1) Rheumatoid factor
2) Tricosporon
3) Aspergillus
4) Capnocytophaga canimorsus septicemia
5) Malignancy
6) Sinuresis fluid
7) Rothia bacteremia
8) Soaps and disinfectants
95
9. List 6 causes as to why an ordinary light microscope would produce a blurry image.
1) Not in focus
2) Oil on the lens
3) Dust or dirt on the eyepiece
4) Improper kolher
5) Using an oil lens without oil on the slide
6) Vibration
7) Air bubbles in the oil
96
10. S. aureus tests with vancomycin MIC of 8 mg/L. What is your interpretation ?
Intermediate
S: =16
CoNS has different Vanco breakpoints. Instead S: =32
97
11. GPC testing slide coag +, tube coag -. What are two possibilities? What if it is PYR + and ODC +? Interpret the susceptibility of this organism if the oxacillin MIC is 1 mg/L.
2 possibilities: S. lugdenesis, S. schleiferi
If PYR+, Orn+ then S. lugdenesis
If the Oxacillin MIC = 1: Susceptible. (=4 resistant for S. aureus and S. ludg)
*Note for CoNS other than S. lugd the breakpoints are instead =0.5 for Oxacillin
98
12. How can a beta-metallolactamase be detected? Explain the principle of this test.
Disk diffusion inhibitor testing with meropenem alone and in combination with dipicolonic acid. If there is increase in zone diameter with addition of dipicolonic acid it is an MBL as the dipicolonic acid inhibits the effect of the MBL allowing the meropenem to be functional. Can also use EDTA.
99
13. Name and explain the mechanisms of resistance for the following combinations:
b. Pseudomonas testing R to carbapenems, ceftaz 4, piptazo 16
c. E. coli R to cefoxitin, S to carbapenems, no change with beta-lactamase inhibitors
d. Enterococcus with a vanco MIC of 32, and a teico MIC of 2
b. Pseudomonas testing R to carbapenems, ceftaz 4, piptazo 16
Pseudo: Piptazo =128
Ceftaz =32
Porin mutation
c. E. coli R to cefoxitin, S to carbapenems, no change with beta-lactamase inhibitors AmpC
d. Enterococcus with a vanco MIC of 32, and a teico MIC of 2
Van B
Or it could also be a vanC with species E. gallinarum or E. casseliflavis (MIC Vanco 8-32)
Van B – Shows in vitro resistance to Vanco and not Teico, but with use of Teico will develop resistance. (MIC Vanco 8-1000)
VanA would have tested resistance to both Vanco and Teico at the beginning
100
14. For the interferon-gamma release assay, what are 2 antigens? What is the necessary transport time? List 2 benefits.
2 Antigens = ESAT6 and CFP10
Early Secreted Antigenic Target 6
Culture Filtrate Protein 10
Transport time – 16 hours for Quantiferon, 8 hours for TSpot
2 Benefits:
1) No false positive in patients who have received BCG vaccine
2) Only 1 appointment needed
101
15. GNCB, testing ox +, cat +, ODC +, indole +, no growth on Mac. Identify.
Pasteurella species
102
16. List 4 biological contaminants of cell monolayers.
1) Bacteria (especially mycoplasma)
2) Yeast
3) Virus
4) Filamentous Fungi
5) WBCs or Epithelial cells
103
List 3 new respiratory viruses discovered in the past 5 years.
1) MERSCoV
2) Avian Influenza H7N9
3) Enterovirus D68
104
18. List for types of winter resp. viruses that can be grown in cell culture, and list 2 cell lines used.
1) Influenza
2) RSV
3) Parainfluenza
4) Adenovirus
105
19. List 2 molecular assays each that correspond to signal amplification, DNA amp., and RNA amp.
Signal amplification:
1) Branched DNA Signal Amplification (bDNA)
2) Hybrid Capture
DNA Amplification:
1) Polymerase Chain Reaction (PCR)
2) Strand Displacement Assay (SDA)
RNA Amplification:
1) Transcription Mediated Amplification (TMA)
2) Nucleic Acid Sequence Based Amplificatoin (NASBA)
3) RT-PCR
106
20. List 2 nucleic amplification tests that are isothermal.
1) LAMP (Loop Mediated Isothermal Amplification)
2) Strand Displacement Assay
3) Transcription Mediated Amplification (AMTD)
4) NASBA (Nucleic Acid Sequence Based Amplification)
107
21. List 2 methods of diagnosis of LGV.
PCR
| Cell Culture – McCoy or HeLa 229 cells
108
22. Name 2 specimens recommended by public health for the detection of measles.
Urine
NP Swab
Throat Swab
109
23. What are 3 modes of transmission of botulism? What are 2 diagnostic methods? What is the treatment for infant botulism?
Modes of transmission:
Ingestion (home canned foods, honey)
Cutaneous (wound botulism, Botox)
Inhalational (bioterrorism)
Diagnostic Methods:
1) Mouse neutralization test (test for the toxin from serum, gastric secretions, stool, or food)
2) Isolation of Clostridium botulinum via culture (from serum, stool or food)
Treatment for infant botulism = BabyBIG – Botulism Immunoglobulin (<1 year olds)
For adults is hBAT (hepavalent Botulism Antitoxin – A,B,C,D,E,F,G)
Botulism is a descending paralysis, involves cranial nerves, toxin mediated
If it is wound botulism add Penicillin and Metronidazole to the treatment
110
24. Why is the cefoxitin disk test done for S. aureus? For coagulase-negative staphylococci?
It is more a surrogate for oxacillin resistance as the oxacillin disk is not reliable to detect resistance for Staph aureus. Indicated the presence of the mecA gene.
For CoNS that are non-S. epidermidis oxacillin MIC may overcall resistance (Oxacillin MIC 0.5-2 called R but may not have mecA); therefore cefoxitin disk is used.
111
25. HIV WB with a single band (at gp41) is shown. What are 3 reasons for false negatives?
1) Acute infection (early seroconversion)
2) Infection with HIV2
3) HIV1 subtype O
4) Low viral load
112
26. List 4 reasons for false positives for the galactomannan test.
1) Therapy with PipTazo
2) Galactomannan in diet
3) Airway colonization with Paecilliomyces, Alternaria, Penicillium in BAL samples
4) Cross reaction with Bifidobacterium
5) Cross reaction with crytptococcus
113
List 6 criteria for the quality assurance of a homebrew molecular assay
1) Positive control
2) Negative control
3) Internal control (within each specimen – Endogenous is human DNA like B-actin, Exogenous is something you add to every patient like MS2 bacteriophage)
4) QC of new lots of reagents
5) External proficiency testing (CAP, QMPLS)
6) Internal proficiency testing (blinded to technologists, exchange samples with other labs)
7) Preanalytical factors – specimen types, temperature of samples
8) Measure DNA concentration after extraction
9) Calibrating equipment
10) Routine maintenance of equipment
11) Verifying temperatures of PCR
12) Development of written laboratory procedures
114
validation of a home brew molecular assay
1) Reportable range
2) Analytical and clinical sensitivity
3) Analytical and clinical specificity
4) Precision
5) Accuracy
6) Reference intervals
115
28. List 2 antigens used as targets in rapid tests for malaria.
1) HRP-2 (histidine rich protein 2)
2) Plasmodium Aldolase
3) Parasite Lactate Dehydrogenase
116
29. Name 6 quality indicators of blood cultures.
1) Contamination rates
2) Volume of blood in bottles
3) Correlation between smear results and culture results
4) Time to calling results to care giver from time of detection of positive blood culture
5) Number of bottles collected
6) Mislabelling or unlabeled samples
117
List 6 elements of a safety program in the laboratory.
1) Biosafety Manual
2) Biosecurity plan
3) Medical Surveillance and Evaluation Program
4) Training Program
5) Safe work practices and Standard Operating procedures
6) Emergency Response Planning
7) Regulatory Compliance
118
31. What are 4 steps to follow if a technician drops a Lowenstein-Jensen with TB in a BSL3?
1) Hold breath
2) Make sure biosafety cabinets are turned on
3) Turn off centrifuges
4) Exit laboratory
5) Keep door shut at least 30 minutes before re-entering
6) Return to clean up wearing proper PPE
7) Follow up exposure with TST or IGRA testing on those who were negative
119
32. List 4 scenarios where a patient may be anti-HCV +, HCV PCR -.
1) Previous HCV infection
2) Successful treatment for HCV
3) No HCV infection with false positive anti-HCV
4) HCV infection with false negative HCV PCR
5) Low viral load
6) Antibodies passively acquired from transfusion
7) Maternal antibotides in babies
120
33. A hemodialysis patient tests anti-HBsAg -, anti-HBc +, and HBV DNA 250. Please give 2 explanations.
1) Window period of acute HBV infection
2) Level of surface antibody below detection limit for the test
3) Occult infection
121
Patient tests EBV VCA IgM + and EBNA +. Please give 2 explanations.
1) Acute infection 6-12 weeks ago (VCA IgM sticks around for up to 3 months, and EBNA is present between 6-12 weeks and last lifelong)
2) Reactivation of EBV
122
35. WNV IgM tests + in patients with rash & fever. What are 3 methods to confirm the diagnosis?
1) WNV Avidity Testing
2) Plaque reduction neutralization testing
3) PCR from the serum
4) CSF IgM serology
5) Acute and convalescent IgG serology
123
36. List 2 arboviruses present in Canada, aside from WNV.
Eastern Equine Encephalitis
St. Louis Encephalitis
Powassan Encephalitis Virus
124
37. List 4 phenotypic differences between E. coli (inactive?) and Shigella.
1) Lysine Decarboxylase
2) Acetate Utilization
3) Mucate
4) Lactose fermenter
5) Gas from glucose for Ecoli
125
38. List 2 GNB’s that can test susceptible to vancomycin in vitro.
Elizabethkingia meningosepticum
| Porphyromonas species
126
39. List 6 diagnostic tests that can be used for culture-negative endocarditis, after clavulin?
1) Coxiella serology
2) Bartonella serology
3) 16S rRNA sequencing of cardiac valve
4) Pathology
5) Whipples testing (PAS and PCR positive)
6) ?
127
40. Name the corresponding host:
a. M. nanum -
b. M. canis –
c. T. rubrum
d. T. verrucosum
e. T. mentagrophytes
40. Name the corresponding host:
a. M. nanum - Pigs
b. M. canis – Cats, Dogs, Horses
c. T. rubrum - Humans
d. T. verrucosum – Cattle
e. T. mentagrophytes – Rodents or rabbits
128
41. List 2 CLSI-approved methods for antifungal susceptibility testing of Candida spp.
1) Broth Microdilution
2) Broth Macrodilution
3) Disk Diffusion
129
42. What are 4 mechanisms for transfer of genetic material between bacteria?
1) Transduction (Bacteriophage)
2) Transformation (Pick up from dead bugs)
3) Conjugation
4) Mobile Genetic Elements (transposons, integrons)
130
43. Child returns from Pakistan with diarrhea and dehydration. Stool culture grows a GNB, ox +, beta-hemolytic.
a. List 3 possibilities.
b. It tests esculin - and ADH +. What is the identification?
a. List 3 possibilities.
Vibrio species
Aeromonas
Plesiomonas (Can be hemolytic!)
b. It tests esculin - and ADH +. What is the identification?
Plesiomonas shigelloides
(Aeromonas is also ADH+ but it is usually bile esculin positive)
Vibrio cholera ADH is negative, for the other Vibrios it can be negative or positive.
131
1. List 5 tick-borne infections and their tick vectors.
1) Lyme Disease (Borrelia burgdorferi) – Ixodes scapularis
2) Rocky Mountain Spotted Fever (Rickettsia rickettsia) – American Dog Tick (Dermacentor variabilis)
3) Anaplasmosis (Anaplasma phagocytophilum) – Ixodes scapularis
4) Babesiosis (Babesia microti) – Ixodes scapularis
5) Relapsing fever (Borrelia hermsii) – Ornithodoros hermsii
6) Human Monocytic Erlichiosis (Erlichia chaffeensis) – Lone Star Tick (Amblyomma americanum)
132
2. What is the mechanism of action of colistin? List 4 GNB’s that are intrinsically R. What are 2 major toxicities?
Mechanism of action = Cationic detergent that damages the bacterial cell membrane and causes leakage of cell contents and cell death
Intrinsically resistant to Colistin:
1) Burkholderia cepacia
2) Morganella morganii
3) Serratia marcescens
4) Proteus mirabilis/vulgaris/penneri
5) Providentia rettgeri/stuartii
6) Vibrio species
2 major toxicities:
1) Renal toxicity
2) CNS toxicity (transient, reversible neurological disturbances)
133
3. 1 y.o. child with fever and unilateral paresis 10 d post-vaccination. List 3 possible explanations.
1) Viral encephalitis unrelated to vaccination
2) Brachial neuritis from tetanus
3) Nerve injury
4) Post vaccination Guillan-Barre Syndrome
134
4. List 4 clinical signs of HIV in children.
1) Failure to thrive
2) Recurrent invasive bacterial infections
3) Generalized lympadenopathy
4) Unexplained Fever
5) Hepatosplenomegally
6) Developmental delay
7) Oral candidiasis
135
5. 17 y.o. male with a CT scan of the head & neck in post-dental procedure. Diagnosis? Possible complication(s)?
Lemieres – septic pulmonary emboli and bacteremia
| Abscess – mandibular osteo
136
List 4 indications for endocarditis prophylaxis peri-dental procedure.
Undergoing gingival or periapical manipulation or mucosal perforation with:
1) Prosthetic valve
2) Previous endocarditis
3) Congenital heart disease
a. Unrepaired cyanotic CHD
b. Completely repaired CHD with prosthetic material up to 6 months post procedure
c. Reparied CHD with residual defects at the site or adjacent to the site with the prosthetic material
4) Cardiac transplant recipients who develop valvopaty
137
7. What is the endocarditis prophylaxis regimen (include dose & duration) if:
a. po –
b. not po –
c. po with penicillin allergy –
d. not po, with penicllin allergy –
a. po – Amoxicillin 2 g PO x 1 30-60 min prior to procedure
b. not po – Ampicillin 2 g IV or Cefazoin 1 g IV x 1
c. po with penicillin allergy – Clindamycin 600 mg po x 1
d. not po, with penicllin allergy – Clindamycin 600 mg IV x 1
138
7. What is the endocarditis prophylaxis regimen (include dose & duration) if:
a. po –
b. not po –
c. po with penicillin allergy –
d. not po, with penicllin allergy –
a. po – Amoxicillin 2 g PO x 1 30-60 min prior to procedure
b. not po – Ampicillin 2 g IV or Cefazoin 1 g IV x 1
c. po with penicillin allergy – Clindamycin 600 mg po x 1
d. not po, with penicllin allergy – Clindamycin 600 mg IV x 1
139
8. In regards to the Menactra vaccine, what is the protein antigen and conjugate? What would you give a 4 y.o. child?
Protein Ag = Neisseria meningititis serogroup A,C, Y, W135 polysaccharides
Conjugate = Diphtheria toxoid protein
Menevo uses A, C, Y, W135 oligosaccharides conjugated to CRM-197 protein
There is also a meningitis polysaccharide vaccine that is not conjugated called Menomune (not routinely recommended)
Booster doses every 5 years
The quadrivalent vaccine is routintely given to adolescents. Outside of ages 12-24 it is only given to high risk groups (above). C
4 year old child – Would give meningococcal group C vaccine (those under 5)
If giving Menactra then give
140
8. In regards to the Menactra vaccine, what are 6 indications?
1) Healthy adolescents and young adults aged 12-24
2) Patients with splenectomy or functional asplenia
3) Laboratory workers potentially routinely exposed
4) Travellers age >2 to a high endemic area
5) Persons with congenital complement deficiency, or primary antibody deficiency
6) Persons with acquired complement deficiency due to receipt of eculizumab
7) Military personnel
8) Outbreaks of a vaccine covered group of Neisseria meningititis
141
9. A child has sickle cell anemia. Would you vaccinate with Menactra?
Yes – Functional asplenia
| 2 doses 8 weeks apart and booster every 5 years
142
10. What virulence factor of group A Streptococcus allows it to cause rheumatic fever?
M protein
M protein is a protein imbedded in the cell wall – prevents opsonization, inhibits complement
The M types associated with Rheumatic Fever = 1, 3, 5, 6, 14, 18, 19, 24
143
What are the Jones Critera for Rheumatic fever?
```
Evidence of GAS infection + 2 major or 1 major and 2 minors
Major:
• Carditis
• Polyarthritis
• Chorea
• Erythema marginatum
• Subcutaneous nodules
Minor
• Arthralgia
• Fever
• Increased acute phase reactants (CRP, ESR)
• Prolonged PR interval
```
144
Duration of prophylactic antibiotics in patients with rheumatic fever?
Carditis and residual heart disease = 10 years, or until age 40 (choose longest)
Carditis with no residual heart disease = 10 years or until age 21 (choose longest)
RF without carditis = 5 years or until age 21 (choose longest)
145
1. In the Prevnar vaccine, what is the protein carrier?
Protein carrier = CRM 197 protein (non toxic mutant of the diphtheria toxin)
Now Prevnar 13 which has 13 serotype specific polysaccharides.
146
12. Which serotype of S. pneumoniae was not included in Prevnar, and has resulted in a large increase in resistance?
19A - It's in preener 13
147
13. 25 y.o. male patient with the following. What would your treatment (incl. dose & duration) be?
a. gonococcal urethritis in India
b. primary HSV
c. LGV
d. latent syphilis, otherwise unspecified
a. gonococcal urethritis in India – Ceftriaxone 250 mg IM x 1 + Azithromycin 1 g PO x 1
b. primary HSV – Valacyclovir 1000 mg po BID x 10 days
c. LGV – Doxycycline 100 mg po BID x 21 days (also treat for gonorrhea here with Ceftriaxone 250 mg IM x 1)
d. latent syphilis, otherwise unspecified – Benzathine Penicillin G 2.4 million units IM weekly x 3
148
14. Histoplasmosis presents with the following. What would your treatment (dose, duration) be?
a. pulmonary nodule
b. chronic cavitary pneumonia
c. severe pneumonia
d. mediastinal fibrosis
a. pulmonary nodule – No treatment
b. chronic cavitary pneumonia – Itraconazole 200 mg PO TID x 3 days, then BID for 1-2 years
c. severe pneumonia – Liposomal Amphotericin B 3-5 mg/kg IV q24 h x 1-2 weeks, then Itraconazole 200 mg po TID x 3 days, then BID to complete 12 weeks total treatment. Can use steroids in the first 1-2 weeks
d. mediastinal fibrosis – No antifungals, surgical management
149
14. Histoplasmosis presents with the following. What would your treatment (dose, duration) be?
a. pulmonary nodule
b. chronic cavitary pneumonia
c. severe pneumonia
d. mediastinal fibrosis
a. pulmonary nodule – No treatment
b. chronic cavitary pneumonia – Itraconazole 200 mg PO TID x 3 days, then BID for 1-2 years
c. severe pneumonia – Liposomal Amphotericin B 3-5 mg/kg IV q24 h x 1-2 weeks, then Itraconazole 200 mg po TID x 3 days, then BID to complete 12 weeks total treatment. Can use steroids in the first 1-2 weeks
d. mediastinal fibrosis – No antifungals, surgical management
150
15. Patient presents with coccidiomycosis. List 4 complications.
Complications:
1) Severe Pneumonia
2) Pulmonary cavity
3) Meningitis
4) CNS Vasculitis
151
15. Patient presents with coccidiomycosis. List 4 indications for treatment.
Treatment Indications:
1) Immunosuppression
2) Pregnancy
3) Meningitis
4) Severe primary infections (weight loss >10%, night sweats >3 weeks, infiltrates more than ½ of 1 lung or poritions of both lungs, persistent hilar adenopathy)
5) Diabetes
6) Cardiopulmonary disease
7) Philipino or African descent
152
List 4 complications of Trichomonas infection in pregnant women.
1) Premature rupture of membranes
2) Preterm delivery
3) Low birth weight
4) Infection in the neonate
153
17. For tigecycline, what class is it, and what is its mechanism of action? What are 2 clinical indications?
Tigecycline = Class is gycylcycline
Mechanism of Action = Inhibits protein synthesis by binding to 30S ribosomal subunit
Clinical Indications:
1) Community Acquired bacterial pneumonia
2) Complicated intra-abdominal infections
3) Complicated skin and soft tissue infections
154
17. For tigecycline List 2 bacteria that are intrinsically R to it in vitro.
Intrinsic Resistance
1) Pseudomonas aeruginosa
2) Morganella morganii
3) Proteus mirabilis
4) Proteus vulgaris
5) Proteus penneri
6) Providencia rettgeri
7) Providencia stuartii
155
18. For chlorhexidine, what are its mechanism of action and spectrum of coverage? Name one advantage over alcohol.
Mechanism of action = Precipitation of cytoplasmic contents
Spectrum = Gram negative, positive, facultative anaerobes, aerobes, viruses and yeast
Advantage over alcohol = Prolonged residual effect (>>6 hours). Also not deactivated by blood, serum or other protein rich biomaterials, concentration much higher than the MIC of bacteria and fungi.
156
19. 13 month old child, non-vaccinated, now with septic arthritis. List 2 possible pathogens that would be GNCB. What empiric therapy would you begin?
1) Haemophilis influenza
2) Kingella kingae
Emperic therapy = Ceftriaxone
157
20. Child with fever, conjunctivitis, cervical adenopathy, and rash. What are 2 possible causes? What question would you ask about vaccines?
1) Measles virus
2) Varicella virus?
3) Adenovirus
4) Kawasakis
158
21. What are 4 causes of meningitis in infants/children? What additional precautions are necessary?
1) Herpes Simplex Virus
2) Group B Streptococcus
3) E. coli
4) Neisseria meningititis
5) Haemophilis influenza
6) Streptococcus pneumoniae
7) Enterovirus
8) Parechovirus
Precautions = Droplet isolation
159
What are 4 virulence factors of Pseudomonas aeruginosa?
4 virulence factors:
1) Exotoxin (Lipid A)
2) Endotoxin (LPS)
3) Pyoveridin
4) Pyocyanin
5) Pili
6) Flagella
7) Quorum Sensing Molecules
8) Adhesins
160
22. Pseudomonas aeruginosa - What mechanisms of resistance:
a. to fluoroquinolones
b. to cephalosporins
c. to carbapenems
d. to aminoglycosides
a. to fluoroquinolones – gyrA; mutation in DNA gyrase
b. to cephalosporins – ESBL or AmpC
c. to carbapenems – porin mutation (OrpD), efflux pump, carbapenemase
d. to aminoglycosides – aminoglycoside modifying enzymes
161
23. For maraviroc, what is its mechanism of action? What test must be done before initiation? What are 2 toxicities associated with it (other than N&V or rash)?
```
Mechanism of action = CCR5 Antagonist, Entry inhibitor by binding the CCR5 coreceptor on CD4 T cells preventing the gp120 and CCR5 interaction
Test before = Tropism test
2 toxicities:
1) Hepatotoxicity
2) CNS (dizziness)
```
162
List 6 epidemiological risk factors for acquisition of CA-MRSA.
1) Incarceration
2) Cosmetic Shaving
3) Group Homes
4) MSM
5) IVDU
6) Aborignial
7) Contact sports or sharing equipment
8) Positive close contacts
9) Military
163
25. What is the treatment (include duration) for fibronodular/bronchiectatic disease due to MAC?
Clarithromycin + Rifampin + Ethambutol for 12 months after culture conversion to negative
Doses:
Clarithromycin = 500 mg PO bid
Rifampin = 600 mg PO daily
Ethambutol 15 mg/kg PO daily
164
26. How would you detect hypersensitivity to abacavir?
Testing for HLA-B*5701 allele
165
List four parasites transmitted by organ donation or blood transfusion.
1) Trypanomoa cruzi
2) Plasmodium species
3) Babesia microti
4) Toxoplasma gondii
5) Leishmania
6) Microfilaria
166
a. List 2 non-infectious causes of PD peritonitis.
1) Icodextrin reaction (component of the dialysate)
2) Allergy to the tubing (eosinophilic peritonitis)
3) Endotoxin contamination of dialysate
4) Malignancy
167
Peritoneal dialysis patient, peritonitic, but no bacteria seen on Gram.
b. What is the probable diagnosis?
c. What empiric therapy would you start?
CAPD associated bacterial peritonitis (often don’t see anything on the gram)
Intraperitoneal with Vanco + Ceftaz
168
List 4 indications to pull the Tenckhoff catheter.
1) Relapsing peritonitis with the same organism
2) Persistent tunnel and exit site infection
3) Fungal periotonitis
4) Mycobacterial peritonitis
5) Refractory peritonitis
6) Intraperitoneal abscess
7) Multiple enteric organisms
169
29. Central line infection, culture grows sporulating, aerobic GBP, growing as beta-hemolytic, lecithinase +, mannitol -, and not growing on the Mac. ID & treatment?
Bacillus cereus
Treatment:
Remove the line and treat with Vancomycin
170
30. List 2 pathogens that are favoured in iron overload. What is a virulence factor in this setting?
1) Vibrio vulnificans
2) Yersinia enterocolitica
3) Zygomyces
4) Listeria monocytogenes
5) Aeromonas hydrophila
Virulence factor = siderophores that bind and sequest iron
171
For Dukoral, what is the target antigen? What are 4 disadvantages to its use? What are 2 alternatives that can be use for diarrhea?
Target antigen = Recombinant Vibrio cholera toxin B, whole cell killed Vibrio cholera O1 vaccine
4 disadvantages:
1) Not for other causes of diarrhea
2) Must be taken 4 weeks prior to travel
3) Requires frequent booster doses
4) Requires 2-3 doses
5) Not effective for O139 strains
6) Nausea, vomiting, abdominal pain
2 alternatives for diarrhea:
1) Shanchol (another cholera vaccine has O1 and O139 but no toxin B)
2) Typhoid vaccine
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32. What is the definition of XDR-TB? What is the treatment?
Definition = Mycobacterium tuberculosis resistant to INH + Rifampin + a fluoroquinole + one of the injectable second line drugs (amikacin, capreomycin, kanamycin)
Treatment of XDR-TB = Any first line drugs that are susceptible + thionamide? + linezolid?
173
33. What is the mode of transmission of the following viruses:
a. Lassa fever –
b. chikungunya –
c. Japanese encephalitis virus -
d. monkeypox
a. Lassa fever – Inhalation of aerosols or contact with body fluids or excreta of infected rodents
b. chikungunya – Mosquito vector
c. Japanese encephalitis virus - Mosquito
d. monkeypox – Contact with infected animals bodily fluids or a bite (rodents, prarie dogs)
174
34. Why daptomycin is not effective in pneumonia?
Antibiotic effect is inhibited by lung surfactant
175
35. Name an indication for the QuantiFERON test. List 3 situations where it is not indicated.
Indication = Investigation for latent TB in a patient previously vaccinated with BCG
Not indicated:
1) Those who require serial testing
2) For the diagnosis of infectious TB
3) To monitor response to antituberculous drugs
176
36. List 4 organisms that are transmitted through aerosols.
1) Tuberculosis
2) Measles
3) SARS
4) Smallpox
5) Varicella virus
177
37. List 3 species of Bartonella, and list one clinical syndrome associated with each.
1) Bartonella henselae – Cat Scratch Disease, Bacillary Angiomatosis, Culture negative IE
2) Bartonella quintana – Trench fever, Culture negative IE, Bacillary Angiomatosis
3) Bartonella bacilliformis – Oroya fever (acute), Verruga peruana (late phase)
178
38. HIV patient, with neurological symptoms, and CD4 count of 66. List 4 possibilities.
1) PML (Progressive Multifocal Leukoencephalopathy – Demylinating disease)
2) Toxoplasmosis
3) Primary CNS Malignancy
4) Cryptococcus
5) Syphilis
6) HIV Encephalopathy
7) TB
8) Bacterial meningitis or brain abscess
179
40. List 3 HIV-associated neoplasias, and for each, name their respective co-factor.
1) Kaposi’s Sarcoma – HHV8
2) Lymphoma - EBV
3) Cervical Cancer – HPV
4) Anal carcinoma – HPV
5) Primary Effusion Lymphoma - HHV8
180
41. Two parasites that can be acquired by eating sushi
1) Diphilobothrium lata
2) Anisakis simplex, Anisakis physeteris (like ascaris, but from fish)
3) Gnathostoma spinigerum (swelling of subcutaneous tissues, eosinophilia)
4) Metorchis conjunctivus
5) Clonorchis
6) Opisthorchis
7) Paragonimus
181
41. Two parasites that can be acquired by eating sushi
1) Diphilobothrium lata
2) Anisakis simplex, Anisakis physeteris (like ascaris, but from fish)
3) Gnathostoma spinigerum (swelling of subcutaneous tissues, eosinophilia)
4) Metorchis conjunctivus
5) Clonorchis
6) Opisthorchis
7) Paragonimus
182
Name 6 organisms for which post-exposure prophylaxis is warranted.
1) HIV
2) Neisseria meningititis
3) Group A Streptococcus
4) Measles virus
5) Brucella
6) Varicella
7) Hepatitis A
8) Hepatitis B
9) Rabies
10) Anthrax
11) Influenza
12) B Virus
13) Bordetella pertussis
183
43. For chlamydia in a pregnant woman list 2 treaments,
2 treatments:
1) Azithromycin 1 g PO x 1
2) Erythromycin 500 mg po QID x 7 days
3) Amoxicillin 500 mg PO TID x 7 days
184
43. For chlamydia in a pregnant woman list 4 other interventions.
4 interventions:
1) Treat partners
2) Counsel regarding safe sex
3) Test for cure in 3-4 weeks
4) Test for other STIs
5) Treat for gonorrhea
6) HIV testing
185
43. For chlamydia in a pregnant woman list 4 other interventions.
4 interventions:
1) Treat partners
2) Counsel regarding safe sex
3) Test for cure in 3-4 weeks
4) Test for other STIs
5) Treat for gonorrhea
6) HIV testing
186
44. List 6 indications for treating a skin abscess with antibiotics.
1) Extensive surrounding cellutitis
2) Systemic signs of infection
3) Abscess >5 cm
4) Multiple lesions
5) Immunosupression
6) No response to I&D
7) Associated comorbidities
8) Extremes of age
187
45. List 2 syndromes caused by HHV-6 in immunocompetent hosts, and 2 in immunocompromised.
Immunocompetent:
1) Roseola infantum
2) Acute Febrile Illness
3) Febrile seizures
4) Meningoencephalitis
Immunocompromised
1) Pneumonitis
2) Encephalitis
3) Hepatitis
188
List 2 organisms that cause fever after the bite of a rat.
1) Streptobacillus moniliformis
| 2) Spirilium minus (Asia, spirochete, never grown in culture)
189
1. 2 technologists disagree on a Gram stain of a CSF: GPC vs artifact? You take a look and have no idea of what it is. Name 4 immediate actions to obtain a response
1) Repeat the gram stain
2) Do an acridine orange fluorescent stain
3) Consult with another microbiologist
4) Do another gram stain with a different fixing method (heat or methanol)
5) Call the ordering physician
6) Look at the cell count and review clinical history
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3. Serology to interpret:
a) VCA IgG +, EBNA -, EA +.
b) anti-HBs +, HBsAg -, anti-HBc -.
a) VCA IgG +, EBNA -, EA +. = Acute EBV infection
| b) anti-HBs +, HBsAg -, anti-HBc -. = Immune to Hepatitis B virus from vaccination
191
4. Serology to interpret (in a potential live kidney donor): HBsAg -, anti-HBs -, anti-HBc +. What test will help clarifying this result?
HBV DNA PCR
192
5. Name 4 indications for a post-HBV immunization anti-HB titre.
1) Dialysis patient or chronic renal disease
2) Immunocompromised
3) Workers immunized because of risk of occupational exposure
4) High risk pregnant women immunized before or after pregnancy
5) Infants born to infected mothers
6) Sexual partners and household contacts of actue cases of chronic carriers of HBV
7) Persons with potential percutaneous or mucosal exposure
193
6. MSDS: What is this acronym for? Identify 5 WHMIS symbols.
Class A = Compressed Gas
Class B = Flammable and Combustible Material
Class C = Oxidizing Material
Class D1 = Poisonous and Infectious causing Immediate serious effects
Class D2 = Poisionous and Infectious causing other toxic effects
Class D3 = Poisonous and Infectious, Biohazardous Infectious Material
Class E = Corrosive Material
Class F = Dangerously Reactive
194
8. Name 5 characteristics of a new strain of C. difficile that is increasing its prevalence and virulence? What is the gold standard test? What are 3 complications of infection?
New strain Characteristics (NAP1/BI/027)
1) Produces a binary toxin
2) Produces larger quantities of toxin A and B (partial deletion of tcdC)
3) Partial deletion of tcdC
4) Resistant to fluoroquinolones in vito
5) More severe disease
6) Increase risk of recurrence
7) More prone to sporulate
195
For C. difficult: What is the gold standard test? What are 3 complications of infection?
Gold standard = Cell culture cytotoxicity assay
Complications of Infection:
1) Toxic mega colon
2) Bowel perforation
3) Ileus
4) Sepsis
196
9. What is the mechanism of resistance and what antiviral would you give in the presence of in the setting of a significant infection with these isolates?
a. HSV and acyclovir
b. influenza A and amantadine:
c. HIV and ZDV/AZT (TAM)
a. HSV and acyclovir – Mutation in the gene encoding the viral thymidine kinase, also alteration of the DNA polymerase. Use Forscarnet
b. influenza A and amantadine: Mutation in the M2 gene (position 31) – Use oseltamivir
c. HIV and ZDV/AZT (TAM) – Mutation in the RT that promotes ATP dependent hydrolytic removal of chain terminating nucleotide monophosphates (selected by thymidine analogues) Use Tenofovir + Emtricitabine + PI?
197
10. Name 4 quality indicators for the pre-analytical phase of blood cultures.
1) Blood volume per bottle
2) Specimen labeling
3) Total blood volume collected
4) Contamination rate
5) Transport time
6) Transport conditions
198
11. Concerning antibiograms, what is a “very major error”?
An isolate reported as susceptible, however it is actually resistant
199
12. Give 3 reasons why it is important to perform MTB molecular testing (epidemiologic) following discovery of a positive case.
1) To determine an epidemiological link to other cases
2) Outbreak investigations
3) Recognize potential laboratory cross contamination
4) Descriminate between exogenous reinfection and endogenous reactivation
5) Resistance determinants
200
13. How can Acanthamoeba be cultured from a cornea scraping?
Resuspend the E.coli in Pages Saline
Plate it on a lawn of E.coli, 30 degrees for 7 days
It can also be cultured in many mammalian cell lines
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14. Name a test that can be used for the dx of hMPV
DFA
202
15. Name 2 cell lines that allows growth of respiratory viruses during winter season.
1) RMK (Primary Monkey Kidney Cell Line)
| 2) MRC5 (Human Fetal Lung Fibroblast)
203
16. 5 indications for HCV RT-PCR.
1) Baseline value after diagnosis
2) Monitor treatment response
3) Suspected acute infection
4) Monitor disease activity prior to initiating treatment
5) Diagnose infection in immunocompromised patient
6) Post liver transplant or post treatment to diagnose recurrence and reinfection
204
17. 4 tests that allows differentiation of Bacillus sp. from Bacillus anthracis.
1) Motility
2) Beta hemolysis
3) Capsule staining (McFayden or India Ink)
4) Penicillin susceptibility
5) B. anthracis will not grow on PEA
6) EYA is positive for the cereus complex but not the other
205
20. What does XDR-TB stand for? What is the definition?
Extensively Drug Resistant Tuberculosis
Definition = Mycobacterium tuberculosis that is resistant to isoniazid and rifampin and at least one fluoroquinolone and at least one of the injectable agents (e.g. capreomycin, kanamycin, amkiacin)
206
21. For C. difficile, name 3 advantages of antigenic tests, and 2 advantages of cell culture w/ cytotoxicity assay.
Antigenic test advantages:
1) Rapid
2) Low cost
3) Easy to perform
Cell Culture Cytotoxicity Assay Advantages:
1) Increased sensitivity
2) Can do typing
3) Gold standard
207
22. Name 4 organisms positive for modified Kinyoun.
1) Nocardia species
2) Rhodococcus equi
3) Legionella micdadei
4) Mycobacterium fortuitum
208
23. What is prozone effect?
High concentration of antibodies inhibits agglutination of the test. Due to high antibody concentration the test is falsely negative, by diluting the sample the test will then be true positive
209
24. What is the most common occupational injury among laboratory technologists?
Ergonomic Injuries
210
25. Name 2 HPV serotypes that cause the majority of cervical cancers, and the 2 most common serotypes causing benign condyloma.
```
Cancer = 16, 18
Codyloma = 6, 11
```
211
```
Selective, Differential, Utility?
Brucella Agar
PEA
BBE
Thio
KVLB
```
Brucella - No, No, Isolation of anaerobes and facultative anaerobes
PEA - Yes, No, Inhibits gram negatives and swarming by some clostridia
BBE - Yes, Yes Bacteroides fragilils group
Thio - No, No Liquid culture media for cultivation of anaerobes, facultative anaerobes and aerobes
KVLB - Yes, No Isolation of bacteroies fragilis group and prevotella
212
```
Selective, Differential, Utility?
Brucella Agar
PEA
BBE
Thio
KVLB
```
Brucella - No, No, Isolation of anaerobes and facultative anaerobes
PEA - Yes, No, Inhibits gram negatives and swarming by some clostridia
BBE - Yes, Yes Bacteroides fragilils group
Thio - No, No Liquid culture media for cultivation of anaerobes, facultative anaerobes and aerobes
KVLB - Yes, No Isolation of bacteroies fragilis group and prevotella
213
27. You suspect a fungi (yeast or mold) on a GIEMSA stain of a pathology cut section. Name 3 other histology stains that can help in the dx.
1) PAS – Periodic Acid Schiff Stain
2) Grocott Methenamine Silver Stain (GMS)
3) Mucicarmine
214
28. Describe 3 physical characteristics of level 3 concerning the ventilation
1) Air filtered through a HEPA filter if recirculated or exhausted away from occupied areas or from building intake locations
2) Negative pressure air flow (inward directional)
3) Supply air duct to be provided with effective backdraft protection
4) All windows must be sealed
215
29. 3 ways to differentiate a thin smear for P. falciparum from Babesia.
1) Multiple Babesia organisms can infect the same cell, usually only one or two organisms in P. falciparum infected cells
2) Babesia organisms are variable in size and the smallest ones are usually smaller than P. falciparum
3) Babesia may form a Maltese cross formation and P. falciparum does not
4) The cytoplasms of Babesia may have a vacuole, P. falciparum does not
5) Extracellular trophozoites are more common in Babesia
6) No gametocytes
216
Treatment for Babesiosis?
Babesiosis treatment = Atorvaquone + Azithromycin (Mild)
Primaquine + Clindamycin for Severe
B. divergens = Plasma exchange transfusion
217
30. List 3 ways to diagnose Coccidioides immitis. Why is a BSC/hood necessary? Explain.
1) Culture of the organism
2) Identification of the spherules in histology slides
3) Antibody assay
4) Urine antigen assay
Requires a BSC/hood as it is a level 3 pathogen. The arthroconidia from the mould form can infect those manipulating the culture.
218
31. Name 2 Candida spp. with reduced susceptibility to amphotericin B.
1) Candidia lusitaniae
2) Candida krusei
3) Candida glabrata
219
32. Name laboratory methods allowing confirmation of an ESBL. Name 2 antibiotics for screening of ESBL.
MAST test – disk diffusion inhibitory assay using Cefotaxime 30 ug and Cefazidime 30 ug with and without clavulinic acid 10 ug
2 screening antibiotics:
1) Cefpodoxime
2) Ceftazidime
3) Cefotaxime
4) Aztreonam
This is for Klebsiella pneumonia, Klebsiella oxytoca, Proteus mirabilis and E. coli.
220
33. E. histolytica : 2 limitations with microscopic diagnosis.
1) Can not distinguish it from E. dispar which is non-pathogenic
2) Low sensivitity depending on technologists experience
221
33. E. histolytica : 2 limitations with microscopic diagnosis.
1) Can not distinguish it from E. dispar which is non-pathogenic
2) Low sensivitity depending on technologists experience
222
34. Enterococcus growing on agar containing vanco 6 mg/L. Name 3 different phenotypic tests allowing differentiation between VanA/B and VanC-containing enterococci (can identify to species). What would you expect the MIC to be for a VanC containing strain of Enterococcus?
1) MGP – Negative for faecalis/faecium
2) Motility – Negative for faecalis/faecium
3) Utilization of xylose – Negative for faecalis/faecium
MIC for VanC Enterococcus is 2-32 or
223
36. Name 3 phenotypic tests that identify Listeria monocytogenes.
1) Bile esculin positive
2) Positive for tumbling motility at 25 degrees
3) CAMP test positive
4) Hippurate positive
5) Catalase positive
6) Beta hemolytic
224
37. 4 causes of false positive VDRL.
1) Rheumatoid factor
2) Malaria
3) Brucellosis
4) Tuberculosis
5) HIV infection
6) Mononucleosis
7) Viral hepatitis
8) LGV
9) IVDU
10) Leprosy
11) Other spirochetes (Lyme)
12) Pregnancy
225
38. Soldier returning from Afghanistan. Chronic ulcer in the leg. What is the most likely diagnosis? Name a method of diagnosis, and list two possible therapies.
Leishmania
Diagnosis with punch biopsy and geimsa stain. Can also use aspirated material or scrapings. Can also do PCR or culture in Tobie’s medium with and without antibiotics.
Thearpy
1) Hyperthermic therapy
2) Intralesional antimony
If it was New World Leish would use Miltefosine (FDA approval), antimony or Amphotericin B.
226
39. Name 3 laboratory methods for ID of aerobic actinomycetes.
1) 16S gene sequencing
2) MALDI TOF
3) PCR with restricition endonuclease analysis
227
40. Name 3 indications for performing AST on anaerobes.
1) Infection not responding to anerobic therapy
2) Confirmation of appropriate therapy for serious infections
3) Periodically monitor local resistance patterns to guide empiric therapy
4) Determine patterns of susceptibility to new antimicrobials
228
41. Name 2 molecular methods allowing identification of M. tuberculosis complex.
1) DNA Probe assay
2) PCR
3) AMTD Assay (Amplified Mycobacterium tuberculosis Direct Assay) - TMA
4) 16S Gene sequencing
229
42. Name the two blood based testing systems for latent TB, describe how they work and what antigens they use. In what clinical situations would you find them to be helpful?
1) QuantiferonTB Gold In Tube Assay
2) TSpot TB Assay
IGRA = Interferron gamma release assay. Measure T cell release of interferron gamma following stimulation by antigens specific to M. tuberculosis.
Antigens = Early Secreted Antigenic Target 6 (ESAT6) and Culture Filtrate Protein 10 (CFP10). Quantiferon also uses TB7.7 Antigen.
Helpful in potential TB exposed patients who have recieved the BCG vaccine
230
45. For each of the following methods of Dx of H. pylori, indicate 1 advantage and 1 disadvantage.
a. Serology:
b. Culture:
c. urea breath test:
d. stool antigen detection:
e. PCR:
a. Serology: Ad= easy to obtain, Dis=May indicate past and not active infection, not useful post eradication, no antimicrobial susceptiblity
b. Culture: Ad= High specificity, Dis= Incubate for 10 days
c. urea breath test: Ad=Noninvasive, Dis= Not available in all centers, rapid, false negatives
d. stool antigen detection: Ad=Does not require specialized equipment, rapid, assess response to treatment Dis=False positives, no susceptiblites
e. PCR: Ad=High Sens, Dis= Equipment needs
231
1. History of a patient with prosthetic knee replacement several months ago and now infected with S. aureus, according to knee fluid aspirate culture (no susceptibility given). What is your proposed Rx?
Vancomycin + Rifampin IV for 2-6 weeks (tailored to sus results), then oral antibiotic + Rifampin for a total of 6 months if retaining the joint
232
2. Name 2 antibiotics that require G6PD testing in a G6PD deficient pt prior to using them (prevention of hemolytic anemia complication).
Dapsone
Nitrofurantoin
Primaquine
233
3. What is the rx for disseminated MAC (CD4
Clarythromycin 500 mg po bid – GI distress, bitter taste, rash, hearing loss
Ethambutol 15 mg/kg po daily– Optic neuritis, GI distress
Rifabutin 300 mg po daily – hepatitis, neutropenia, GI distress
+/- Amikacin
234
4. An HIV patient is treated with DDI, 3TC & efavirenz. He has a positive urine test for cannabinoids and insists he’s never taken drugs. What is the explanation?
Cross reaction of the test with efavirenz
235
Candidemic patient with Candida spp. in the ICU, with a non-tunneled central line in place. Name 3 interventions besides antifungals.
Remove the central line
Opthalmology eye exam
Repeat blood cultures until negative
236
6. Name 2 blood tests replacing PPD/Mantoux test. List for each the type of antigen used, as well as an indication where these tests are clearly superior to traditional TST.
1. QuantiferonTB Gold In Tube Test IGRA – ESAT6, CFP10, TB7.7
2. TSPOT.TB IGRA – ESAT6, CFP10
Do not react with BCG vaccine
237
7. Pathology report of a recent brain biopsy indicating strong suspicion for CJD. Indicate all the steps of sterilization required for instruments that have been used in the procedure.
Instruments should ideally not be reprocessed and rather discarded.
If they must be reprocessed then…
Keep them moist after contamination
Clean routinely
Soak in 1 Normal sodium hydroxide
Autoclave at 134 degrees celcius for 60 min in a prevacuum sterilizer
238
8. Newborn from an HIV+ mother + no prior medical follow-up. Name one intervention.
Start therapy in the newborn with PO zidovudine + Neverapine + Lamivudine
Order HIV PCR testing on the newborn.
Also you would give IV AZT to the mom during delivery
239
9. HIV and 5 prophylactic rx (primarys or secondary)/infectious conditions
a. Thrush
b. PJP
c. Toxoplasma
d. MAC
e. LTBI
f. CMV retinitis
a. Thrush - Treat with Fluconazole, usually no suppression until severe or frequent recurrences. If suppression then fluconazole 100 mg po daily
b. PJP – TMP-SMX 1 ds tab po daily, Dapsone, Pentamidine
c. Toxoplasma – TMP-SMX 1 ds tab po daily (if IgG positive toxo proph)
d. MAC – Azithromycin 1200 mg po weekly
e. LTBI – Isoniazid 300 mg po x 9 months + pyridoxine 25 mg po daily
f. CMV retinitis – Valgancyclovir 900 mg daily (2nd proph)
240
10. Clinical case. Question : what are the criteria according to ATS guidelines that allows dx of atypical NTM pulmonary infection in this pt?
Pulmonary symptoms, nodular or cavitary opacities on CXR or CT scan showing multifocal bronchiectasis and small nodules AND
Isolation of NTM in culture from 2 or more sputum and 1 or more BAL or biopsy or transbronchial biopsy with NTM features on histopathology and a positive culture for NTM from the biopsy or a sputum or bronchial wash
241
11. Clinical scenario of a splenectomized patient presenting with recurrent sepsis (no organisms
given) .
a. What will your approach be to prevent future episodes?
Vaccinate against pneumococcus and Neisseria and Hib
Check they have received all primary series vaccinations
Counsel regarding dog bites
Can give amoxil prophylaxis, higer dose available if they develop fever
Vaccinate household contacts?
242
b. The asplenic patient is bitten by a dog and develops a cellulitis. What prophylaxis/treatment would you give considering the patient has an anaphylactic allergy to penicillin? c. Name a bacteria from dog bite that could give rise to fulminant sepsis in these patients
Clindamycin + Doxycycline
Capnocytophaga canimorsum
243
12. Treatment of pregnant woman for: (dose and duration)
a. Chlamydia
b. primary syphilis
c. Trichomonas vaginitis
d. pharyngeal gonorrhoea
a. Chlamydia – Azithromycin 1 g PO x 1 or Amoxicillin 500 mg po x 7 days
b. primary syphilis – Benzathine Penicillin G 2.4 MU IM x 1
c. Trichomonas vaginitis – Metronidazole 2 g po X 1 or 500 BID x 7 days
d. pharyngeal gonorrhoea – Ceftriaxone 250 mg IM x 1
244
13. Name 2 risk factors for CMV disease post-SOT
1. Recipient CMV positive prior to transplant
2. Rejective treated with T-cell depleating agents
3. High dose steroids
245
14. 5 risk factors for colonization by ESBL enterobacteriaceae.
```
Length of hospital stay
Central venous catheter
Emergency abdominal surgery
Low birth weight
Prior administration of any antibiotic
Prior residence in long term care facility
Presence of urinary catheter
Hemodialysis
Ventilatory assistance
Travel to endemic area
```
246
14. 5 risk factors for colonization by ESBL enterobacteriaceae.
```
Length of hospital stay
Central venous catheter
Emergency abdominal surgery
Low birth weight
Prior administration of any antibiotic
Prior residence in long term care facility
Presence of urinary catheter
Hemodialysis
Ventilatory assistance
Travel to endemic area
```
247
15. Name 3 indications for HIV genotyping
Entry into care
When starting antiretrovirals
Treatment failure
Pregnancy
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16. Name 4 classes of antiretrovirals. For each, indicate mode of action, mechanism of resistance and one example.
a. NNRTI – Binds to an Inhibits the reverse transcriptase by inducing a conformational change, resistance by point mutations of the reverse transcriptase, neverapine. NNRTIs are easy to have resistance as it’s just a point mutation.
b. protease inhititors – binds to and inhibit the viral protease activity, point mutations of viral protease, lopinavir
c. NRTI – nucleoside/nucleotide analogues that are incorporated into the virus by the reverse transcripase and inhibit further replication, resistance by mutation in the reverse transcriptase, tenofovir
d. integrase inhibitor – prevents the proviral DNA from integrating into the hosts chromosome by blocking strand transfer, resistance by point mutation in the viral integrase, raltegravir
e. CCR5 receptor antagonist –inhibits the gp120/CCR5 interation thereby blocking the virus from attaching to the CD4 T cell, resistance by changes in co receptor usage to CXCR4, maraviroc
f. fusion inhibitor – peptide mimic of gp41, resistance by mutations in gp41 envelope gene, enfuvirtide
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17. Name 4 indications for HAV vaccine.
```
Travel to endemic region
Household contact of a case
Daycare attendees during an outbreak
Persons with chronic liver disease
Workers involved in research of HAV or production of HAV vaccine
Persons with hemophilia A or B receiving plasma derived replacement clotting factors
IVDU
MSM
```
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18. Name 3 indications for follow-up HBsAb titre following HBV vaccination.
Dialysis patient or chronic renal disease
Those with risk of occupational exposures (ex. Health care workers)
Persons with potential percutaneous or mucosal exposure (MSM, IVDU)
Immunocompromised persons
High risk pregnant women immunized prior to pregnancy
Infants born to infected mothers should be tested 1 month after completion of vaccine series
Sexual partners and household contacts of cases
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19. Mechanism of action of tigecycline? Name 2 organisms considered resistant to it. Name 4 advantages compared with piptazo.
Tigecycline – Binds to the 30S ribosomal subunit inhibiting protein synthesis
Resistant – Pseudomonas aeruginosa, Proteus species, Providentia species, Morganella species
Advantages – No renal adjustements necessary, broad coverage, active against atypical bacteria
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20. H. influenza meningitis in a 3 year old. What prophylaxis should be given to his younger unvaccinated siblings (4 & 6 y.o.)? To their parents? An aunt who visited for a few hours?
The 2 siblings and the parents should receive once daily rifampin for 4 days
The aunt does not need prophylaxis.
The reason the whole house is being vaccinated is because there is an unvaccinated child 48 months of age then no one needs prophylaxis.
Recommend vaccination to the 4 year old (
253
21. What is the mechanism of action of colistin?
Acts as a cationic detergent, damages cell membrane causing leakage of cytoplasmic contents
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22. WNV IgM elevated. 3 confirmatory methods. Name 2 other arboviruses in Canada.
Plaque reduction neutralization assay
CSF IgM
PCR
2 other arboviruses in Canada – St Louis encephalitis, Eastern equine encephalitis, Powassan
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B. pertussis
a. phases of the disease and duration:
b. name appropriate test according to timing after onset of symptoms
c. 4 measures for in-hospital patients w/ symptoms x 4 wks
d. IC measures for contacts
e. indications for vaccination
a. phases of the disease and duration:
Catarrhal - 1 week
Paroxysmal – 3 weeks
Convalescent – 4-6 weeks
b. name appropriate test according to timing after onset of symptoms
NP swab for culture within 3 weeks after symptom onset
PCR up to 6 weeks
c. 4 measures for in-hospital patients w/ symptoms x 4 wks
- No isolation
- Vaccine once resolved
- Contact tracing
- Contact prophylaxis or vaccine if indicated
d. IC measures for contacts
Erythromycin x 7 days or
Azithromycin x 5 days
```
e. indications for vaccination
All children 7 should have one dose of Tdap
All adults should have one does of Tdap
Post Exposure
Persons new to Canada
```
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24. H. influenzae b meningitis in a 2 year old, unvaccinated. What prophylaxis should be done, and with what?
If there is another child in the household who is
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25. Name 3 treatment for influenza A as well as a contraindication for each.
1. Oseltamivir – allergy
| 2. Zanamivir – allergy, age
258
26. Most common cause of pneumonia associated with hemolytic anemia?
Mycoplasma pneumonia
259
27. A patient is diagnosed with dengue fever after returning from Haiti. He wants to return to Haiti for visits regularly in the future. What should you tell him, regarding risk of dengue in the future, and regarding measures to reduce risk of acquiring dengue?
If he is infected with a serotype other than the one infected with now he is at risk for severe dengue infection (Dengue hemorrhagic fever)
Reduce risk by protecting self from mosquito bites with barriers, deet, avoid standing water
Day biting mosquitoes – screen building, not bug nets
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28. Case of severe malaria. List 6 complications. Name three diagnostic methods to prove P. falciparum other than smear. How would you treat? What if she was pregnant?
1. Severe anemia
2. Renal failure
3. Seizure
4. DIC
5. Death
6. Respiratory distress
7. Metabolic acidosis
8. Hepatic failure
9. Hypoglycemia
Other than smear: Rapid antigen test, PCR, Serology
Treatment = Artesunate
If pregnant = Artesunate
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29. Name the etiologic agent of:
a. Melioidosis
b. Glanders
c. trench fever
d. bacillary angiomatosis
e. rat-bite fever –
f. cat scratch disease
29. Name the etiologic agent of:
a. Melioidosis – Burkholderia pseudomallei
b. Glanders – Burkholderia mallei
c. trench fever – Bartonella quintana
d. bacillary angiomatosis – Bartonella henselae and quintana
e. rat-bite fever – Streptobacillus monoiformis
f. cat scratch disease – Bartonella henselae
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31. Compare scombroid and ciguatera. Given an example of fish affected, mode of acquisition, one symptom
Scombroid - Hisitdine, Tuna, Mackerel, Mahi-Mahi, Facial rash, flushing, swelling, respiratory distress
Ciguatera - Marine biotoxin ciguatoxin, Snapper, Baracuda, Grouper, Eel, GI, then 48 hours later neuro symptoms
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31. Compare scombroid and ciguatera. Given an example of fish affected, mode of acquisition, one symptom
Scombroid - Hisitdine, Tuna, Mackerel, Mahi-Mahi, Facial rash, flushing, swelling, respiratory distress
Ciguatera - Marine biotoxin ciguatoxin, Snapper, Baracuda, Grouper, Eel, GI, then 48 hours later neuro symptoms
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32. Clinical picture of necrotizing fasciitis given. Name the most important treatment of this condition, and indicate what else you would do (which antimicrobial?).
Most important is early surgical management
| Antibiotics : PipTazo (or Carbapenem) + Clindamycin (for antitoxin) + Vancomycin
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33. Type & duration of isolation for: (A=airborne, C=contact, D=droplet)
a. disseminated zoster
b. measles
c. pertussis
d. hepatitis A
e. influenza
33. Type & duration of isolation for: (A=airborne, C=contact, D=droplet)
a. disseminated zoster – Airborne and contact for duration of the illness
b. measles – Airborne until 4 days after rash onset (all of illness if immunocompromised)
c. pertussis – Droplet until 5 days after initiation of abx therapy or 3 weeks after cough onset if no antibiotics are given
d. hepatitis A – Contact until 1 week after onset of symptoms for incontinent and diapered patients
e. influenza – Droplet for the duration of the illness
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33. Type & duration of isolation for: (A=airborne, C=contact, D=droplet)
a. disseminated zoster
b. measles
c. pertussis
d. hepatitis A
e. influenza
33. Type & duration of isolation for: (A=airborne, C=contact, D=droplet)
a. disseminated zoster – Airborne and contact for duration of the illness
b. measles – Airborne until 4 days after rash onset (all of illness if immunocompromised)
c. pertussis – Droplet until 5 days after initiation of abx therapy or 3 weeks after cough onset if no antibiotics are given
d. hepatitis A – Contact until 1 week after onset of symptoms for incontinent and diapered patients
e. influenza – Droplet for the duration of the illness
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34. Young man with encephalitis. Probable diagnosis? What therapy (dose, duration)?
HSV encephalitis
Acylovir 10 mg/kg q8h x 14-21 days
(1-2 cases in Ottawa a year)
MRI finding is temporal lobe encephalitis
EEG finding is PLEDS (periodic lateralized eliptiform discharges)
PCR can be negative early on in the illness
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35. A CT scan and a CXR of a neutropenic pt are shown.
| a. What are 3 criteria (according to EORTC/MSG) for diagnosis of invasive pulmonary aspergillosis?
- lesion on CT scan
- growth in culture
- pathologic
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36. Name 2 limitations to galactomannan test.
Patient population – heme malignancies and stem cell transplant
False positives with piptazo therapy
False positives with other invasive mycoses (histo, blasto, Penicillium)
Cross reaction with gut bacteria
Decreased sensivitity on mould active agents
270
37. Name 4 microorganisms (genera and species) acquired by a tick bite as well as the associated disease.
Borrelia burgdorferi – Lyme disease
Ehrlichia chaffeensis – Human Monocytic Erlichiosis
Rickettsia rickettsia – Rocky Mountain Spotted Fever
Anaplasma phagocytophilum – Human Granulocytic Anaplasmosis
Rickettsia africae – African Tick Typhus
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38. Indications for exclusion from work and duration for :
a. smear + TB
b. VZV
c. herpetic whitlow
a. smear + TB – until smear negative and on therapy for at least 2 weeks with clinical improvement. If MDR TB it’s 6 weeks of thearpy
b. VZV – exclude until all lesions have crusted over. If shingles can work as long the lesions can be covered
c. herpetic whitlow – exclude if lesion can not be covered, if not until lesion has crusted over
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39. Peritoneal dialysis pt., peritoneal fluid culture positive for E. coli, Enterococcus spp., anaerobes. What is this clinical picture compatible with? 4 interventions to consider?
Secondary bacterial peritonitis
Interventions:
- Broad spectrum antibiotics
- Removal of the catheter
- Image the abdomen to assess for collections
- Surgery for source control if deemed necessary (? perforation)
- Gastric suction
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40. Clinical picture of post-antibiotic diarrhea (clearly C. difficile). Name 2 complications.
Ileus
Toxic Megacolon
Hypotension
Intestinal perforation
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41. Name 3 conditions necessary for a flu pandemic.
New subtype for which there is little or no human immunity
Easily transmitted between humans
Ability to infect and replicate in humans
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42. A large clinical case of a young man returning from an exotic travel, presenting with rash distributed to the face and extremities, some lymphadenopathy; blood test relatively normal. Name 4 differential diagnosis as well as their respective vectors/reservoir if applicable.
1. Dengue fever - mosquito
2. Chickungunya – mosquito
3. Syphilis
4. Ricketsial infection
5. Measles
6. Acute HIV
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42. A large clinical case of a young man returning from an exotic travel, presenting with rash distributed to the face and extremities, some lymphadenopathy; blood test relatively normal. Name 4 differential diagnosis as well as their respective vectors/reservoir if applicable.
1. Dengue fever - mosquito
2. Chickungunya – mosquito
3. Syphilis
4. Ricketsial infection
5. Measles
6. Acute HIV
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43. Name 3 most common infections seen frequently in patients treated with TNF alpha inhibitors. What is the pathophysiology of this susceptibility?
```
TB
HBV
Listeria
Legionella
Herpes zoster infection
Histoplasmosis
Aspregillus
JC Virus
Pneumococcal
Nocardia
Salmonella
Toxoplasmosis
```
Impaired cell mediated immunity
278
44. Name 4 infection control measures in the management of a norovirus outbreak.
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Hand hygiene
PPE
Bleach disinfection
Contact precautions
Designated bathrooms
No visitation
No mass gatherings
```
