Infectious Disease

Question 1

Risky travel activities with HIV-1/HIV-2 EIA positive. Western shows bands for p24 (HIV-1 capsid antigen) and gp41 (HIV-1 transmembrane glycoprotein). What are the four groups of HIV-1?

Answer 1

1. M (main - A, B, C,D,F,G,H,J,K)
2. O (outlier)
3. N (non-M, non-N)
4. P (primate *gorillas to humans)

Question 2

Risky travel activities with HIV-1/HIV-2 EIA positive. Western shows bands for p24 (HIV-1 capsid antigen) and gp41 (HIV-1 transmembrane glycoprotein). What are the next two tests to order?

Answer 2

1. HIV-1 RNA viral load
2. HIV-1 genotyping

Question 3

Which HIV genes are sequenced for resistance?

Answer 3

Protease
Reverse transcriptase

Question 4

Ampliprep quantitative HIV-1 testing from 48-10,000 copies (1.68-7 log copies/mL) targets which HIV-1 M and N (and circulating recombinant forms -CRF) gene and which Group O gene?

Answer 4

gag (M and N)
long terminal repeat (O)

Question 5

RealTime quantitative HIV-1 testing from 40-10,000 copies (1.68-7 log copies/mL) targets which HIV-1 gene?

Answer 5

integrase

Question 6

None of the FDA-approved HIV viral load tests detect or quantify __

Answer 6

HIV-2

Question 7

HIV-1 genotyping is limited by the need for _____ HIV-1 RNA copies/mL in plasma

Answer 7

500 copies/mL

Question 8

HIV-1 resistance to _________, _______ and _____ inhibitors are not detected with the FDA-cleared platforms

Answer 8

fusion inhibitors
integrase inhibitors
CCR5 inhibitors

Question 9

Beyond HIV sequencing, a ________ assay measuring IC50 and IC90 can be performed for resistance.

Answer 9

phenotypic

Question 10

HIV-1 phenotyping is limited by the need for _____ HIV-1 RNA copies/mL in plasma

Answer 10

500

Question 11

After RealTime HIV-1 testing below 40 copies/mL and additional testing by Ampliprep 2, Aptima RNA qualitative TMA, what conclusion may be made after 12 months about the patient and their quantitative testing?

Answer 11

HIV-1 elite controller (high CD4 T-cells and low viral copies)

Question 12

Describe long-term non-progressors in HIV

Answer 12

CD4 > 500 without ART, detectable viral load under 5,000

Question 13

Intra-assay variation for HIV-1 load is 0.1 to 0.2, there for a variation greater than ______ log copies/ml (3 fold) is required to represent biologically meaningful change in viral load

Answer 13

0.5

Question 14

For positive 4th generation tests (HIV-1/2 antibodies and p24 capsid Ag) and negative Western, what are the two possibilities

Answer 14

Acute infection with p24 positive only
False positive

Question 15

For positive 4th generation tests (HIV-1/2 antibodies and p24 capsid Ag) and negative Western, what testing could help distinguish whether there is an acute infection or a false positive?

Answer 15

HIV-1 RNA testing

Question 16

HIV-1 groups (M-9 subtypes, N, O, P) are based on sequence diversity in ______ and ________ genes

Answer 16

gag, env

Question 17

HIV-1 group M subtype __________ is the most common globally while subtype __________ is the most common in the US

Answer 17

C (globally)
B (US)

Question 18

HIV binds _________on T-cells (using gp120 envelope protein) in syncytium inducing viruses and _______ on macrophage in non-syncytium inducing HIVs.

Answer 18

CXCR4 - CD4 Tcells
CCR5 - macrophage

Question 19

A homozygous 32 bp ______ in CCR5 is associated with resistance to HIV-1

Answer 19

deletion

Question 20

Beyond CCR5, __________ is associated with lower steady state viral levels and slow disease progression

Answer 20

HLA-I

Question 21

Where is the predominant geographic location of HIV-2

Answer 21

West Africa
Same as group O (non-M, non-N)

Question 22

What is the target for the Ampliprep HIV-1 version 1 test?

Answer 22

gag

Question 23

Which of the following statements regarding HIV-1 genotyping is false?
A. Current FDA-cleared assays generally use sequencing technology to compare the patient’s sequence with the wild-type
B. Genotyping can be performed by the TRUGENE and ViroSeq assays
C. Genotyping reports provide information on antiretroviral drug resistance
D. Patients who are treatment naïve should have genotyping tests performed
E. Performing genotyping tests is the only way to determine a patient’s antiretroviral drug resistance profile

Answer 23

E.
phenotype assays also exist

Question 24

Which of the following is not a characteristic of elite controllers?
A. They constitute <1% of the global HIV infected population
B. They have a normal CD4+ T-cell count
C. They maintain a viral load greater than 5000 copies/mL
D. They typically maintain a viral load less than 50 copies/mL
E. They will likely have a positive HIV-1 antibody screen

Answer 24

C.
Should be < 5000

Question 25

CMV ganglciclovir resistance is based on which two genes?

Answer 25

UL97 - viral kinase UL54 - DNA-dependent DNA polymerase

Question 26

Which CMV gene more commonly has mutations?

Answer 26

UL97 1292-1998 - amino acids 430-666

Question 27

Gangciclovir is an acyclic 2-deoxyguanosine that acts as a "suicide substrate" of the CMV DNA-dependent DNA polymerase encoded by the _____ (pol) gene.

Answer 27

UL54

Question 28

Gangciclovir is initially phosphorylated by the ________-encoded viral kinase and then by cellular kinases

Answer 28

UL97 = viral kinase

Question 29

CMV UL97 S/T kinase develops resistance through mutations at amino acids 460(________-_________ domain), 520 and 591-607 which is hypothesized to be the __________-_________ domain

Answer 29

460- phospho-transfer 591-607 gangciclovir-binding

Question 30

Phenotypic assays in CMV define resistance by an IC50 change greater than ______ fold.

Answer 30

5-fold (IC50 change)

Question 31

Given a major mutation in CMV (>5X IC50 change), what is the next step in therapy?

Answer 31

Foscarnet (herpes virus DNA polymerase) - does not require UL97 kinase

Question 32

Cidofovir is another inhibitor of herpesvirus DNA polymerases but is not a recommended as a first line therapy. Why?

Answer 32

common UL54 (polymerase) mutations confer cross-resistance between cidofovir and gangciclovir. Also nephrotoxic

Question 33

What should be done clinically with a patient who has no resistance mutations and does not appear to be responding virologically?

Answer 33

Reduction of immunosuppression to augment the gangciclovir

Question 34

In addition to reduction of immunosuppression in a patient that does not appear to be responding to gangciclovir (virologically), what are the treatment changes in low and high risk (lung, CMV negative patient in CMV positive allograft)patients

Answer 34

low- gangciclovir intensification high- empiric foscarnet

Question 34

CMV syndrome is a constellation of ______, ______ and _______

Answer 34

fever, anorexia and malaise

Question 35

Due to the absence of a reference standard, patients should be followed for CMV titers using a _______________ assay

Answer 35

single (assay)

Question 36

_______(pol) mutations that show resistance in gangciclovir show mutations in codons 300-1000

Answer 36

UL54

Question 37

Gangciclovir inhibits CMV replication by disrupting

Answer 37

chain elongation

Question 38

Gangciclovir resistance in solid organ transplant occurs most commonly due to:

Answer 38

Viremia after months of treatment

Question 39

Gangciclovir resistance in solid organ transplanst most commonly occur in which pretransplant CMV serologic profile? (Donor____, recipient _____ )

Answer 39

Donor positive, recipient negative

Question 40

Which HR-HPV type accounts for the highest percentage of disease of the cervix?

Answer 40

HPV 16

Question 41

Transmission of HR-HPV which can lead to cervical cancer occurs by which route?

Answer 41

Contact by infected epithelium with mucous membranes (sexual activity)

Question 42

The recommendations from the 2006 Consensus Guidelines suggest all of the following EXCEPT: A. All women 30 years and older should be screened for high-risk (HR) HPV DNA testing from their cytology specimen   B. HPV-16 and HPV-18 genotyping is not recommended as the initial screening test for women 30 years and older   C. HPV-16 and HPV-18 genotyping should be used for women 30 years and older with HR HPV DNA to determine whether to perform colposcopy and biopsy of suspicious lesions or wait 12 months for repeat cytology testing   D. HR HPV DNA testing should be included in evaluating a patient with atypical glandular cells of undetermined significance (AGUS) E. Women with atypical squamous cells of undetermined significance (ASC-US) cytologic results of any age should have HR HPV DNA testing on that cytology specimen    

Answer 42

E. Women with atypical squamous cells of undetermined significance (ASC-US) cytologic results of any age should have HR HPV DNA testing on that cytology specimen   No ASCUS testing in less than 20 years

Question 43

The only FDA-approved methods currently available for detection of HR HPV are based on which methods?

Answer 43

RT PCR and invader/cleavase signal amplification

Question 44

Describe the Digene (Qiagen Inc) Hybrid Capture II assay?

Answer 44

It is a signal amplification method using RNA probes and antibodies specific for RNA:DNA duplex hybrids

Question 45

What gold standard assay for cervical cancer screening?

Answer 45

biopsy

Question 46

Pap smears suffer from low __________ (sensitivity/specifity) but have high_________ (sensitivity/specifity

Answer 46

Paps have: low sensitivity high specificity

Question 47

FDA-approved Digene HPV Hybrid Capture2 (Qiagen) and Cervista HPV HR (Hologic) and Cervista HPV-16/18 genotyping are approved with the _________ liquid-based cytology media

Answer 47

Thin-prep (Hologic) not Surepath (BD)

Question 48

Cervista HPV HR test (Hologic) is a ____ ______ method of detection with _________ reactions

Answer 48

signal amplification 3 reactions

Question 49

Cervista HPV HR test (Hologic) uses complementary oligonucleotides and a _________ which cleaves the FAM (6-carboxyfluorescein) fluorophore if the 3 targets are present.

Answer 49

cleavase

Question 50

Cervista HPV HR test (Hologic) (Hologic) uses a RED (Redmond Red dye) tagged oligonucleotide to the human _____ gene as an internal control

Answer 50

H2AB

Question 51

Cervista HPV HR test (Hologic) FAM FOZ (fold over zero) divides the ____ FAM FOZ value from any one of the 3 reactions by the ______ FAM FOZ value

Answer 51

highest/lowest

Question 52

Cervista HPV HR Invader test (Hologic) uses _____ technology to generate a ______ sequence (when target is present) that is complementary to a secondary probe. The FLAP sequence binding on the secondary probe in a simultaneous reaction generates red fluorescence. Red means there ______ in the sample while FAM (green) fluorescence means there is _____.

Answer 52

invader FLAP sequence red = DNA green = HPV

Question 53

Digene HPV Hybrid Capture2 (Qiagen) is a _______ signal amplification technology based on RNA probes to detect ____ high-risk HPV types

Answer 53

chemiluminescent (RLU) 13

Question 54

The Digene HPV Hybrid Capture2 (Qiagen) test has 93-96% ________ but the potential for ________ __________

Answer 54

93-96% sensitivity false positives (cross reaction with LR HPV)

Question 55

Gardasil contains HPV types ______ and _____ as well as LR HPV types ______ and _____

Answer 55

16, 18, 6, 11

Question 56

The strain of lymphogranuloma venereum (LGV) round in European outbreak of rectal proctitis?

Answer 56

L2b

Question 57

Which LGV gene is sequenced to determine the serovar?

Answer 57

Outer membrane protein A gene (ompA)

Question 58

Performing an FDA-cleared test on a non-approved specimen requires a ___________?

Answer 58

validation

Question 59

A Method Other Than Acceleration (MOTA) score provides a ___________ (quantitative/qualitative) result

Answer 59

qualitative (does not indicate level of organism present in sample)

Question 60

When should an internal control be used for a C. trachomatis molecular test s?

Answer 60

when testing a crude lysate

Question 60

Differential for proctitis in HIV-1 positive MSM?

Answer 60

1. Neisseria gonorrhoeae 2. Chlamydia trachomatis serovars D-K and L1-L3 3. HSV 4. HPV 5. Syphilis

Question 61

Serology tests can/cannot? differentiate C. trachomatis A-K vs L1-3?

Answer 61

Cannot

Question 62

______ __________ ____________ uses a bumper primer, a 5' primer with restriction site, thiolated cytosine, exonuclease nicking, DNA polymerase and fluorescently tagged probe to achieve isothermal amplification

Answer 62

strand displacement amplification

Question 63

Which enzymes are used in the isothermal Aptima CT assay - transcription mediated amplification (TMA)?

Answer 63

Reverse transcriptase (with RNaseH activity) RNA polymerase (with T7 promoter included in primer)

Question 64

LGV proctitis requires a 21 day course of __________________

Answer 64

doxycycline

Question 65

The MRSA ___________ gene responsible for production of an altered Penicillin Binding Protein, PBP2a, which maintains staphylococcal cell wall integrity because of its low affinity for ?-lactam antibiotics.

Answer 65

mecA

Question 66

What is the genetic target in the commercial MRSA PCR assays?

Answer 66

SCCmed/orfX insertion site

Question 67

Which variants in S. aureus growth can cause discrepancies with PCR results?

Answer 67

anaerobic, blood requirements, low density growth and salt sensitivity

Question 68

Healthcare facilities can use ____________ surveillance to support an overall infection control program

Answer 68

active surveillance

Question 69

When the SCCmec cassette is inserted into the open reading frame (orfX) gene of S. aureus, it becomes the primary genetic basis for methicillin resistance.

Answer 69

staphylococcal cassette chromosome (SCCmec)

Question 70

MRSA PCR as an "improved gold standard" has _____________ PPV than cultures but a _____________ NPV

Answer 70

lower PPV higher NPV

Question 71

MRSA PCR assay results can be MRSA positive, despite a culture negative status, for ______ to _____________% of specimens tested

Answer 71

5 to 10%

Question 72

The BD GeneOhm and Cepheid Xpert both have ____________ performance for MRSA detection in Canada and Europe

Answer 72

diminished

Question 73

Cepheid MRSA Expert has ____________ ____________ spores as a sample processing/assay control and PCR inhibition control

Answer 73

Bacillus globigii

Question 74

Cepheid MRSA Expert measures the __________ ____________ control to ensure proper bead hydration, reaction-tube filling, probe integrity, and fluorophore stability.

Answer 74

probe check (control) -PCC

Question 75

In addition, low bacterial densities in the nares samples can render the culture negative and the PCR positive, or vice versa, because low bacterial densities, typical with emerging subpopulations, may cause both methods to produce sporadic positive or negative results under the parameters described by the statistical phenomenon known as the ____________ effect.

Answer 75

Poisson (effect)

Question 76

There is documented evidence that respiratory specimens, among others, are prone to false-________ results, which can be corrected by the use of selective agar to confirm the true presence of MRSA present in low density

Answer 76

negative (false-negative)

Question 77

Microbial growth characteristics can also be responsible for PCR-positive, culture-negative results. Reasons for the discrepancy can include staphylococcal strains that _________ slowly, those that require the presence of _________ for growth, and those that grow only in _________ or __________ environments. In these cases, PCR would identify these fastidious species but the strains would not grow without extraordinary measures for cultivation. Furthermore,______ _________ variants of MRSA are a subset of fastidious strains and are becoming more commonly isolated, growing slowly on blood-based agar and sometimes on chromogenic agar, although they may not exhibit the typical colony color change on certain varieties of agar.

Answer 77

grow (slowly) blood (for growth) anaerobic or high salt small colonogy

Question 77

In addition to the microbial reasons for the discrepant results, an alternative scenario is possible. “______ __________ variants” of MRSA can exist, when the mecA gene is lost from the bacterial chromosome but the insertion site remains. Recurrent commercial PCR assays target genetic regions upstream from the mecA gene

Answer 77

empty cassette (variants)

Question 78

Deletions within the SCCmec region of MRSA strains result in the absence of a functional _____________gene,

Answer 78

mecA

Question 79

Deletions within the SCCmec region of MRSA strains result in the absence of a functional mecA gene, but these “empty cassette variants” cause PCR-positive, culture-negative results because current commercial PCR assays target genetic regions___________ from the mecA gene

Answer 79

upstream

Question 80

The mecA and ____________ genes are targets for Cepheid’s second-generation MRSA assay, which also detects and confirms MSSA.

Answer 80

spa - (staphylococcus protein A)

Question 81

The __________ gene is a recombinase gene responsible for insertion of the SCCmec cassette

Answer 81

ccr

Question 82

Differential for proctitis in MSM?

Answer 82

Neisseria gonorrhoeae Chlamydia trachomatis Treponema pallidum

Question 83

Chlyamydia trachomatis serovars that cause lymphogranuloma venereum (LGV)?

Answer 83

L1 to L3

Question 84

Strand displacement amplification (SDA) uses two outer _____ primers and two inner primers. The inner primers contain a 5' tail region with a _____ enzyme recognition site

Answer 84

bumper primers (outside) nicking enzyme recognition site (inside) --allows for second strand displacement (DNApol lacks exonuclease - ex-Klenow)

Question 85

_______ scores are used in diagnostic assays that do not involve amplification techniques like PCR, to measure the signal generated by a reaction, allowing for the detection of pathogens.

Answer 85

MOTA (method other than amplification)

Question 86

What is the length of doxycycline use for LGB proctitis vs non-LGV Chlamydia infections?

Answer 86

21 days for LGV (RNA up to 16 days) vs 7 days

Question 87

Chlamydia trachomatis possesses a _______ 7.5-kb plasmid of unknown function.

Answer 87

cryptic

Question 88

Which Chlamydia serovars are confined to the mucosal epithelial surfaces

Answer 88

A-K

Question 89

The 2003 LGV European outbreak of proctitis was a new variant of LGV known as serovar ______

Answer 89

L2b

Question 90

Which gene is sequenced to determine the LGV serovar variations? A. Cryptic plasmid DNA   B. Outer membrane protein A gene   C. Reticulate body DNA   D. Sequencing does not need to be performed; serologic antibodies are used   E. None of the above

Answer 90

B. Outer membrane protein A gene   ompA

Question 91

A molecular test has only been FDA-cleared for endocervical swabs, urethral swabs, and male or female urine specimens. Your infectious disease clinicians request that you offer testing on rectal swabs. Which of the following statements is the most correct with regard to reporting the results? A. Inform the clinicians that testing the rectal swab is not possible B. Inform them you will call them with result but not put the result in the medical record C. Just test the rectal swab, no further laboratory validation is needed   D. Laboratory validation of rectal swab specimens would be required before clinical testing could be offered   E. You cannot perform a validation if the assay was not FDA-cleared for that specimen type    

Answer 91

D. Laboratory validation of rectal swab specimens would be required before clinical testing could be offered

Question 92

Which of the following statements is true of the MOTA score? A. The assay provides both a quantitative and qualitative result B. The assay will not provide any results; you will have to determine the cutoff for each sample C. The assay will provide a qualitative result D. The assay will provide a quantitative result E. The MOTA score must be confirmed by DNA sequencing before reporting the patient's results

Answer 92

C. The assay will provide a qualitative result

Question 93

When is an internal control needed for a C. trachomatis molecular test? A. An internal control is never required B. Not required for cervical or urine specimens C. Required regardless of the extraction or test method D. Should be used in the APTIMA CT assay E. Should be used when testing a crude lysate

Answer 93

E. Should be used when testing a crude lysate

Question 94

Name three drug classes of influenza anti-virals and give examples

Answer 94

1. NA inhibitors - oseltamavir and zanamavir 2. M2 ion channel inhibitors - amantadine, rimantidine 3. PA - cap endonuclease inhibitor - baloxavir

Question 95

Which NA point mutation is associated with resistance to oseltamavir?

Answer 95

H275Y

Question 96

Which PA point mutation is associated with resistance to oseltamavir?

Answer 96

I38 ---- I38T, I38F, I38M,

Question 97

Which to influenza genes are targeted to detect an IAV infection?

Answer 97

1. M 2. HA1 vs HA3

Question 98

The most common mutation that confers oseltamivir resistance is found in the gene encoding of which influenza A protein? A. Hemagglutinin   B. M2 ion channel   C. Neuraminidase   D. Nonstructural protein   E. Nucleoprotein

Answer 98

C. Neuraminidase  

Question 99

What is the amino acid change for the most common mutation that confers oseltamivir resistance? A. Asn294Ser   B. Glu198Asp   C. His275Tyr   D. Iso222Val   E. Ser31Asn

Answer 99

C. His275Tyr  

Question 100

The use of single-tube rRT-PCR to amplify influenza A virus allows detection of: A. Viral complementary RNA B. Viral genomic RNA C. Viral messenger RNA D. A and B E. A, B, and C

Answer 100

E. A, B, and C

Question 101

Immunocompromised child with ILI. What nucleic acid test provides the best chance of identifying the responsible respiratory virus? A. Influenza A matrix rRT-PCR B. 2009 Influenza A (H1N1) subtyping and H275Y oseltamavir -R rRT-PCR C. Influenza B rRT-PCR D. Respiratory syncytial virus rRT-PCR E. RT-PCR/liquid-phase, bead-based respiratory viral array

Answer 101

E. RT-PCR/liquid-phase, bead-based respiratory viral array

Question 102

URI with 2009 pH1N1 and concern for viral PNA. What specimen should be tested for IAV? A. Bronchoalveolar lavage (BAL) fluid   B. Nasopharyngeal Swab   C. Plasma   D. Serum   E. Throat Swab

Answer 102

A. Bronchoalveolar lavage (BAL) fluid

Question 103

Pertussis has a high mortality in __________?

Answer 103

infants

Question 104

Pertussis deaths can be due to PNA, hypoxia-induced seizures secondary to ________ and an often-fatal pulmonary __________ syndrome

Answer 104

apnea (seizures) pulmonary HTN - hypertension

Question 105

Bordetella pertussis is sensitive to _____________ antibiotics

Answer 105

macrolide (ZPAK)

Question 106

Is pertussis reportable?

Answer 106

Yes

Question 107

For which of the following uses is B. pertussis detection indicated? A. Nursing home exposures. B. Antibiotic cessation (test for cure) in 2 yo hospitalized for pertussis. C. Antibiotic cessation (test for cure) in 85 yo hospitalized for pertussis. D. To diagnose the cause of two weeks of chronic cough and post-tussive emesis in a 30-year-old woman E. To diagnose the cause of sleep apnea in a 42-year-old

Answer 107

D. To diagnose the cause of two weeks of chronic cough and post-tussive emesis in a 30-year-old woman

Question 108

Culture in addition to PCR is recommended because: A. Antibiotic resistance is common among B. pertussis isolates and should be documented   B. False-positive PCR results can be more readily detected   C. New variants of B. pertussis can be identified   D. Only B. pertussis isolates with certain carbohydrate utilization profiles are pathogenic   E. PCR is not as sensitive as prolonged culture

Answer 108

B. False-positive PCR results can be more readily detected   B. pertussis vs B. holmesii - same trx

Question 109

Which of the following specimens is optimal for detection of B. pertussis by PCR? A. Calcium alginate swab of anterior nares   B. Calcium alginate swab of posterior nasopharynx C. Dacron swab of the anterior nares   D. Rayon swab of the posterior nasopharynx   E. Rayon swab of the throat

Answer 109

D. Rayon swab of the posterior nasopharynx   Dacron or Rayon alginate can inhibit PCR

Question 110

Compared to pertussis toxin promoter, the target sequence IS481 is: A. Equally sensitive and specific   B. Less sensitive and specific   C. Less sensitive, but more specific   D. More sensitive and specific   E. More sensitive, but less specific

Answer 110

E. More sensitive, but less specific IS481 is a repetitive element found in B. pertussis and B. holmesii.

Question 111

B. pertussis detected. What should be the treatment? A. Ampicillin   B. Azithromycin   C. Aztreonam   D. Ceftriaxone   E. Metronidazole

Answer 111

B. Azithromycin  

Question 112

What is the leading cause of infection for hospitalization of these infants/young children? A. Adenovirus   B. Herpes virus   C. Influenza virus   D. Respiratory syncytial virus   E. Streptococcus pneumoniae

Answer 112

D. Respiratory syncytial virus  

Question 112

Which of the following techniques is the most sensitive for detection of common respiratory viruses? A. Conventional culture of a nasal swab specimen B. Direct fluorescent antibody testing of a sputum specimen C. Membrane-based enzyme immunoassays performed on a nasal swab specimen D. Real-time reverse transcription polymerase chain reaction (RT-PCR) performed on a nasal swab specimen   E. Viral culture testing of a bronchoalveolar lavage specimen

Answer 112

D. Real-time reverse transcription polymerase chain reaction (RT-PCR) performed on a nasal swab specimen

Question 113

Which answer is incorrect regarding hMPV infection? A. Coinfection with other respiratory viruses is commonly reported   B. It has been identified worldwide   C. It is a member of the Paramyxoviridae family and is subclassified in the Pneumovirinae subfamily   D. Patients present with symptoms of the common cold including cough, coryza, wheezing, and fever   E. There is seasonal presentation of infection particularly in the summer months in temperate climates

Answer 113

E. There is seasonal presentation of infection particularly in the summer months in temperate climates

Question 114

Reverse transcription real-time PCR reactions include which of the following steps? A. Creation of cDNA   B. Hybridization to a fluorescently labeled bead C. Nucleic acid extraction   D. RNA amplification   E. Signal amplification generated by a biotin-labeled probe

Answer 114

A. Creation of cDNA  

Question 115

No amplification of the internal control in a PCR-based assay for respiratory virus detection most likely indicates which of the following? A. If no viruses were detected then the reaction should be repeated B. Multiple viruses are present in the patient’s specimen C. No virus is present in the patient’s specimen D. No results can be reported if one or more of the viral amplifications are positive E. The specimen was sufficient and should be reported as negative

Answer 115

A. If no viruses were detected then the reaction should be repeated

Question 116

Which polyomavirus is associated with 95% of polyoma-associated nephropathy (PVAN)?

Answer 116

BK virus = 95% JC = PML presumptive PVAN can be made in biopsy-negative cases with persistently elevated viruria (>10^7 viral copies/mL) or viremia (>10^4 viral copies/mL) for more than three weeks BK viruria typically precedes viremia by one to three months- asymptomatic screening

Question 117

1. BK virus is in the same virus family as: A. Adenovirus B. Herpes simplex virus C. Human papilloma virus   D. Parvovirus B19   E. Simian virus 40

Answer 117

E. Simian virus 40

Question 118

Polyomaviruses are associated with: A. Merkel cell carcinoma   B. Polyomavirus-associated nephropathy (PVAN)   C. Progressive multifocal leukoencephalopathy (PML)   D. B and C   E. A, B, and C

Answer 118

E. A, B, and C

Question 119

PVAN most commonly occurs in the context of: A. Diabetes B. Hematopoietic stem cell transplant   C. HIV   D. Renal transplant   E. Small bowel transplant

Answer 119

D. Renal transplant  

Question 120

The best way to ensure the portability of quantitative nucleic acid amplification testing results is to: A. Require all quantitative testing be sent to a central reference lab   B. Require exactly the same assays be used in every lab   C. Require more stringent proficiency testing criteria   D. Require more stringent quality control criteria   E. Require the use of international quantitative calibration standards    

Answer 120

E. Require the use of international quantitative calibration standards    

Question 121

The BK results are as follows (see table): What is the best interpretation for these results? A. The patient’s viremia is fluctuating. The tests offered by the laboratories are equivalent B. The patient’s viremia is fluctuating. The test offered at Laboratory X has increased analytical sensitivity compared to Laboratory Z   C. The patient’s viremia is stable. The test provided at Laboratory Z has an approximately one-log negative bias compared to Laboratory X   D. The patient’s viremia is stable. The test offered at Laboratory X has decreased analytical specificity compared to Laboratory Z  E. The patient’s viremia is stable. The tests offered by the laboratories are equivalent

Answer 121

C. The patient’s viremia is stable. The test provided at Laboratory Z has an approximately one-log negative bias compared to Laboratory X  

Question 122

From the list below, select the most likely cause(s) of the patient’s respiratory distress? A. Adenovirus   B. Herpes simplex virus   C. HMPV, parainfluenza virus 3   D. RSV, HMPV, parainfluenza virus 3   E. RSV only

Answer 122

D. RSV, HMPV, parainfluenza virus 3  

Question 123

Are all three viruses identified in our patient involved in the respiratory disease? A. It is impossible to determine whether all three viruses were involved in the infection, because some of these viruses are commonly found in people without disease   B. No, only RSV causes respiratory disease that is severe enough to cause this patient’s respiratory distress   C. No, these combined viruses are unlikely to cause disease, because human cells can only be infected with one virus at a time   D. Yes, all these three common respiratory pathogens could be involved in causing the respiratory distress in a patient with these risk factors E. Yes, the patient is predisposed to mixed infections because of her Asian descent

Answer 123

D. Yes, all these three common respiratory pathogens could be involved in causing the respiratory distress in a patient with these risk factors

Question 124

What is (are) the most likely event(s) that led to the patient’s infection with multiple viruses? A. Ethnic descent in a transplant patient   B. Immunosuppression and exposure to multiple family members   C. Immunosuppression and seropositivity to CMV   D. The patient’s age   E. The patient’s gender

Answer 124

B. Immunosuppression and exposure to multiple family members

Question 125

In light of these results, what would you tell a physician who calls to question your laboratory’s results for this patient with three viruses identified? A. Only RSV is pathogenic enough to cause disease of this severity   B. The results are reliable   C. The results are unreliable D. The results are valid; however it may be prudent to resubmit a second specimen for testing E. The laboratory has experienced contamination; a new specimen should be collected and sent to a reference laboratory for testing

Answer 125

B. The results are reliable  

Question 126

Given that the specimen was inadvertently frozen, what could you do for the patient to avoid a recollection of the BAL? A. Heat the frozen specimen to 95°C to remove nucleases   B. Nothing, there is no way to avoid recollection   C. Re-extract the specimen stored at ?20°C   D. There is no need for a recollection of the specimen   E. Use the cytology specimen

Answer 126

B. Nothing, there is no way to avoid recollection