Deck 15: Diagnosing Infections

Question 1

Which test is especially good for bacteria that are not readily cultivated in the lab?

A)Gram stain
B)direct antigen testing
C)dichotomous key
D)direct fluorescence antibody (DFA)testing
E)phage test

Answer 1

D

Question 2

Biochemical tests include all of the following except

A)presence of catalase.
B)presence of oxidase.
C)colony morphology.
D)sugar fermentation.
E)gas production.

Answer 2

C

Question 3

Antibody testing requires

A)a known antigen.
B)a known antibody.
C)both a known antigen and a known antibody.
D)either a known antigen or a known antibody.

Answer 3

A

Question 4

Specimen collection

A)is always done by a medical professional.
B)must be done under sterile conditions.
C)must utilize aseptic techniques.
D)does not require special handling.
E)All of the choices are correct.

Question 5

Animals are required for the cultivation of

A)Treponema pallidum.
B)Pseudomonas.
C)Streptococcus.
D)Salmonella.
E)Clostridium.

Question 6

A serum titer involves

A)serially diluting a serum sample.
B)determining the lowest dilution of serum that produces a visible reaction.
C)determining the highest dilution of serum that produces a visible reaction.
D)the Western blot method.
E)None of the choices is correct.

Question 7

Which of the following is involved in the in vitro diagnostic testing of serum?

A)mycology
B)hematology
C)serology
D)histology
E)virology

Question 8

Which of the following is not a genotypic method of identification?

A)rRNA sequencing
B)PCR
C)biosensor
D)direct antigen testing
E)DNA analysis with probes

Question 9

A positive serological test for tuberculosis indicates that

A)the patient has active tuberculosis.
B)the patient is an asymptomatic carrier of tuberculosis.
C)the patient has been exposed to tuberculosis.
D)All of the choices are correct.

Question 10

Which sample is not typically collected by sterile needle aspiration?

A)blood
B)urine
C)cerebrospinal fluid
D)tissue fluids
E)All of the choices are collected by sterile needle aspiration.

Question 11

Urine and fecal specimens require

A)sterile collection conditions.
B)incubation in differential media.
C)incubation in selective media.
D)both sterile collection conditions and incubation in differential media.
E)both incubation in differential media and incubation in selective media.

Question 12

Which of the following is not a phenotypic method of identification?

A)morphology
B)Gram stain reaction
C)acid-fast reaction
D)antibody response
E)endospores

Question 13

Serological testing can be used to test each of the following except

A)blood serum.
B)cerebrospinal fluid.
C)urine.
D)saliva.
E)skin.

Question 14

The property of a test to detect only a certain antibody or antigen,and not to react with any others is

A)cross reaction.
B)agglutination.
C)precipitation.
D)specificity.
E)sensitivity.

Question 15

The property of a test to detect even small amounts of antibodies or antigens that are test targets is

A)cross reaction.
B)agglutination.
C)precipitation.
D)specificity.
E)sensitivity.

Question 16

Each of the following are appropriate specimens for bacterial culture except

A)saliva.
B)skin.
C)spinal fluid.
D)hair.
E)throat.

Question 17

The primary advantage of genotypic methods of identification is

A)they are easier than any other method.
B)they are less expensive than other methods.
C)they are widely available.
D)culturing of the organism is not required.
E)All of the choices are correct.

Question 18

Titer is the amount of

A)antigen in serum.
B)antibody in serum.
C)WBC in serum.
D)complement in serum.
E)memory cells in serum.

Question 19

Phage typing is useful in identifying

A)Treponema pallidum.
B)Mycobacterium leprae.
C)Streptococcus.
D)Salmonella.
E)Clostridium.

Question 20

Serological testing relies upon

A)the specificity of the Fc region of antibodies.
B)the specificity of the variable regions of antibodies.
C)a patient who is not immunocompromised.
D)very high viral or bacterial load in the patient.
E)None of the choices is correct.

Question 21

Serological testing always involves reactions between specific antibody and antigen.

Question 22

Serological tests should have low sensitivity and specificity.

Question 23

Soluble antigens are detected in this type of test.

A)cross reactions
B)agglutination
C)precipitation
D)specificity
E)sensitivity

Question 24

It is necessary to do lab tests to diagnose all diseases.

Question 25

In precipitation tests,the antigen

A)is a soluble molecule.
B)is an insoluble molecule.
C)is a whole cell.
D)antibody complex settles to the bottom of the tube.
E)None of the choices is correct.

Question 26

Syphilis can be diagnosed by the

A)Weil-Felix reaction.
B)rapid plasma reagin test.
C)Widal test.
D)latex agglutination test.
E)antistreptolysin O test.

Question 27

Which test is the confirming test for people who initially tested antibody-positive in the screening ELISA test for HIV?

A)Ouchterlony double diffusion
B)Western blot
C)immunelectrophoresis
D)radioimmunoassay (RIA)
E)Quellung

Question 28

Which test uses radioactive isotopes to label antibodies or antigens in order to detect minute amounts of corresponding antigen or antibody?

A)Ouchterlony double diffusion
B)Western blot
C)immunelectrophoresis
D)radioimmunoassay (RIA)
E)Quellung

Question 29

The Quellung test involves

A)a precipitation reaction.
B)an agglutination reaction.
C)a fluorescent reaction.
D)a lysis reaction.
E)a radioimmunoassay.

Question 30

When minute samples of DNA need to be genetically analyzed for identification purposes,which test can be effectively used?

A)direct fluorescence antibody
B)Widal
C)Weil-Felix reaction
D)PCR
E)direct antigen reaction

Question 31

What type of test will detect whole antigens?

A)cross reaction
B)agglutination
C)precipitation
D)specificity
E)sensitivity

Question 32

Which test is used to confirm scarlet fever?

A)ELISA
B)Western blot
C)Widal test
D)complement fixation
E)antistreptolysin O

Question 33

Horseradish peroxidase and alkaline phosphatase are enzymes used in _____ tests.

A)Western blot
B)ELISA
C)direct fluorescent antibody
D)indirect fluorescent antibody
E)None of the choices is correct.

Question 34

Serotyping of pneumococcus based on capsular polysaccharide is performed in

A)Ouchterlony double diffusion.
B)Western blot.
C)immunelectrophoresis.
D)radioimmunoassay (RIA).
E)the Quellung test.

Question 35

Which test is used to confirm rheumatic fever?

A)ELISA
B)Western blot
C)Widal test
D)complement fixation
E)antistreptolysin O

Question 36

The tuberculin skin test is read

A)within 1 hour.
B)after 12 hours.
C)from 12-24 hours.
D)from 24-48 hours.
E)from 48-72 hours.

Question 37

Precipitation tests involve all of the following except

A)they rely on formation of visible clumps for detection.
B)they include the VDRL test for syphilis.
C)they are often performed in agar gels.
D)they can be done in a test tube by carefully adding antiserum over antigen solution.
E)a cloudy or opaque zone developing where antigen and antibody react.

Question 38

When antibodies or other substances in serum cross-react with the test reagents,a false positive result can occur.

Question 39

The Western blot test is confirmatory for HIV because

A)it is more sensitive than the ELISA.
B)it has fewer false positives than the ELISA.
C)it tests for more HIV antibodies than ELISA.
D)it is easier to interpret than ELISA.
E)All of the choices are correct.

Question 40

A positive indirect ELISA result requires

A)one known antibody,one unknown antibody,and an unknown antigen.
B)a known antigen,an unknown antibody,and a known antibody
C)two known antibodies and one known antigen.
D)two known antibodies and one unknown antigen.
E)All of the choices are correct.

Question 41

Fluorescent dye can be used as a label to trace antibody-antigen reactions in an ELISA assay.4-2-2013

Question 42

Jared had an ELISA test sent for HIV screening,which came back positive.You tell Jared that this is a highly sensitive test,but not as specific.Jared is understandably confused.You apologize for using medical jargon,and then clarify in which of the following ways?

A)"It's possible that this is a false-positive result,since the test may have been positive for something other than HIV."
B)"It's unlikely that this is a false-positive result,since the test is so specific it doesn't miss a positive result."
C)"It's possible that this is a false-positive result,since high specificity means the tests are rarely accurate."
D)"It's unlikely that this is a false-positive result,since we've never misdiagnosed HIV based on this test."

Question 43

Halley's CRP came back markedly elevated.What finding does this point to?

A)An elevated CRP is a highly sensitive urinary tract infection marker.
B)An elevated CRP points to inflammation from any of a variety of sources.
C)An elevated CRP shows elevated levels of vitamin C in the blood.
D)An elevated CRP points to a bacterial infection and nothing else.

Question 44

You inform Jared that a Western blot test will be performed to confirm or deny diagnosis.You tell Jared that the Western blot test is a more specific test.This time,you catch yourself using medical jargon again,and clarify in which of the following ways:

A)"It's possible that this is a false-positive,since the test may have been positive for something other than HIV."
B)"The Western blot test is a more specific test and is unlikely to generate a false positive result.This will be used to confirm or refute the ELISA test results."
C)"It's possible that this is a false-positive,since high sensitivity means the tests are rarely accurate."
D)"It's unlikely that there would be a false-positive result,since this is the only test that can really diagnose HIV."

Question 45

The lumbar puncture was especially painful and uncomfortable for Halley.What step listed below is most important to be taken to ensure the procedure does not need to be performed a second time?

A)The specimens must be properly labeled.
B)The specimens must be properly obtained and stored.
C)The specimens must be collected in sufficient amounts.
D)The specimens must be properly transported.
E)All of the choices are equally important.

Question 46

The Weil-Felix test is used for diagnosing salmonellosis.

Question 47

What kind of evidence are the sores around Tyler's mouth classified as?

A)signs and symptoms
B)ELISA
C)genetic evidence
D)microscopic evidence

Question 48

Halley's nasal wash results came back,and were reported as "insufficient cells available for testing." What does this mean?

A)Halley is free of infection since insufficient cells could be isolated.
B)A smaller sample must be sent,since the counts clouded the results.
C)This is a very specific and sensitive finding that points to a viral infection.
D)The sample was inadequate,and the nasal wash procedure must be repeated.

Question 49

Jared informs you that he previously had a negative HIV PCR test performed about a month ago.What is your interpretation of this information?

A)PCRs are rarely accurate.
B)He may be lying,since the ELISA came back positive.
C)It is possible the ELISA was a false-positive,and the Western blot must be performed to confirm.
D)The HIV PCR is outdated,and does not pick up modern strains of the virus.

Question 50

Tyler's results came back as being positive for Herpes simplex virus.Tyler's mother is mortified,as she does not believe her son is sexually active.After you explain that the presence of HSV does not imply sexual contact,you offer that the results are accurate.Which of the following reasons best demonstrates this line of thinking?

A)Signs and symptoms don't lie.
B)PCR tests are highly sensitive and specific.
C)The ELISA is an excellent screen for HSV.
D)Apologize for being so certain,because further testing must be done.

Question 51

The tuberculin test is an example of an in vitro serological test.

Question 52

Halley's urine for culture was collected using a clean-catch method.After inoculation and incubation,several organisms were identified in amounts that were specified as normal microbial flora.What does this mean?

A)Halley is superinfected and needs immediate treatment.
B)It is impossible to interpret these results,and another clean-catch urine specimen needs to be cultured.
C)The results point to an infection,but due to multiple organisms,further testing needs to be done to isolate the offending microbe.
D)This is a common finding due to contamination of a clean-catch urine sample with normal microbiota from the urogenital area.

Question 53

What kind of evidence will the results of Tyler's PCR provide?

A)signs and symptoms
B)ELISA
C)genetic evidence
D)microscopic evidence