Deck 15: Diagnosing Infections

Question 1

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 1

colony morphology

Question 2

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 2

a known antigen

Question 3

Each of the following are appropriate specimens for bacterial culture except ________.

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

Answer 3

hair

Question 4

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

Question 5

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 6

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 are correct.

Question 7

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 8

Phage typing is useful in identifying ________.

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

Question 9

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 10

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 11

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 12

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 13

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 14

Animals are required for the cultivation of ________.

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

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

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 are correct.

Question 17

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 18

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 19

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 20

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 21

What type of test will detect whole antigens?

A) Cross reaction
B) Agglutination
C) Precipitation
D) Specificity
E) Sensitivity

Question 22

Soluble antigens are detected in this type of test.

A) Cross reactions
B) Agglutination
C) Precipitation
D) Specificity
E) Sensitivity

Question 23

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

A) Immunochromatography
B) Western blot
C) Immunelectrophoresis
D) Radioimmunoassay (RIA)
E) ELISA

Question 24

The tuberculin skin test is read ________.

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

Question 25

The indirect ELISA test is used to diagnose all of the following except ________.

A) strep throat
B) HIV
C) hepatitis A and C
D) Helicobacter
E) Rickettsia

Question 26

In vivo testing is useful for diagnosing ________.

A) tuberculosis
B) rubella virus
C) hepatitis A
D) HIV
E) whooping cough

Question 27

The Weil-Felix test is used for diagnosing salmonellosis.

Question 28

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 are correct.

Question 29

Serological testing always involves reactions between specific antibody and antigen.

Question 30

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 31

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

A) Direct fluorescence antibody
B) Immunofluorescence
C) Weil-Felix reaction
D) PCR
E) Direct antigen reaction

Question 32

Serological tests should have low sensitivity and specificity.

Question 33

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

A) Immunochromatography
B) Western blot
C) Immunelectrophoresis
D) Radioimmunoassay (RIA)
E) Weil-Felix

Question 34

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

Question 35

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 36

Syphilis can be diagnosed most easily by ________.

A) the Weil-Felix reaction
B) direct fluorescence
C) ELISA
D) agglutination
E) immunochromatography

Question 37

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 38

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

Question 39

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

Question 40

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 are correct.

Question 41

An outbreak of hepatitis A originating in a popular chain of restaurants serving fresh produce necessitated the rapid analysis of the viral genome in order to trace its source. The genome was scanned and analyzed multiple times to reduce errors. This is an example of ________.

A) whole genome sequencing
B) PFGE
C) FISH
D) microarrays

Question 42

The three main techniques for identifying microorganisms from patient samples are specificity, sensitivity, and biochemical.

Question 43

The benefit of "lab on a chip" technology over standard microarrays is that ________.

A) lab on a chip technology has miniaturized testing to carry out analyses using minute amounts of reagents, whereas microarrays still require larger volumes of reagents in comparison
B) lab on a chip technology requires little technical training compared to analyses using microarrays
C) lab on a chip technology is invaluable for developing countries, where the reagents, refrigeration and trained personnel required for microarrays are limited
D) All of the choices are benefits of "lab on a chip" technology.

Question 44

FISH and microarrays both use probes to hybridize to sequences of the pathogen genome. They differ in that ________.

A) FISH involves adding fluorescently labeled probes directly to a patient's sample, whereas microarrays involve the attachment of thousands of potential gene sequences from pathogens to an absorbent plate and adding DNA from the patient's sample to it, allowing matching sequences to hybridize
B) microarrays involve adding fluorescently labeled probes directly to a patient's sample, whereas FISH involves the attachment of thousands of potential gene sequences from pathogens to an absorbent plate and adding DNA from the patient's sample to it, allowing matching sequences to hybridize
C) FISH involves scanning and analyzing the pathogen genome multiple times, whereas microarrays involve separating DNA samples into fragments using restriction enzymes, then exposing the fragments to varying voltage levels from three different directions
D) microarrays involve scanning and analyzing the pathogen genome multiple times, whereas FISH involves separating DNA samples into fragments using restriction enzymes, then exposing the fragments to varying voltage levels from three different directions

Question 45

Microbes can be identified using automated biochemical tests, often without incubation. An example of this type of test would include ________.

A) a test for the presence of the enzyme urease, that would change the media from yellow to red
B) binding of fluorescent antibodies to the specific antigenic determinant in the sample
C) exposure to DNA probes that are either fluorescently labeled or will initiate a color change when bound to their complement
D) digestion of the genomic DNA by restriction enzymes, followed by separation by gel electrophoresis

Question 46

Techniques that make use of probes that hybridize to specific sequences of a pathogen's genome include ________.

A) FISH and microarrays
B) ELISA and FISH
C) FISH and Western blot
D) PFGE and ELISA

Question 47

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

Question 48

The ability to miniaturize genetic testing on a chip much smaller than a microarray plate will see its greatest benefit in developed countries so the large corporations can process genetic data much more efficiently.

Question 49

A protein fingerprint of a patient's blood sample can be created by adding the sample to a metal plate and striking it with a laser. This causes the sample to become ionized and the ions from the sample are guided into a machine that separates them and identifies them according to their mass-to-charge ratio. This process describes ________.

A) MALDI-TOF
B) "lab on a chip"
C) PFGE
D) PCR
E) FISH

Question 50

Microorganisms can be identified from a patient sample using biochemical tests based on the premise that ________.

A) organisms have a unique combination of metabolic enzymes that are displayed when color-changing dyes are utilized to demonstrate their physiological response to specific substrates
B) organisms display specific antigens that can be bound by color-changing antibodies that allow the clinician to locate and identify the pathogen
C) organisms will not grow on certain media types and can be selected for on others
D) bacteriophages infect certain bacterial cells and the specificity can be used to identify the organism

Question 51

Immunologic methods of identifying microorganisms in a patient sample are characterized as those that ________.

A) rely on the specificity of antibodies to target a single antigen
B) directly examine the organism's appearance or behavior, which includes its metabolic abilities, environmental preferences and drug susceptibilities
C) analyze the genetic makeup of the microorganism, which conclusively diagnoses the infection
D) amplifies the microbial DNA in the patient's sample and during the process, identifies the organism through the use of known primers

Question 52

Which of the following is not one of the main categories for identifying microbes?

A) Radiologic
B) Phenotypic
C) Genotypic
D) Immunologic

Question 53

The three main techniques for identifying microbes are ________.

A) phenotypic, immunologic, and genotypic
B) microscopic, macroscopic, and biochemical
C) PCR, electrophoresis, and biochemical
D) DNA, RNA, and antibodies

Question 54

MRI, CT and PET scans are useful diagnostic tools in cases where infection is located in deep tissues, thereby saving the patient from an invasive biopsy.

Question 55

The patient's CRP is markedly elevated. What does this indicate?

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 is diagnostic of a fungal infection.
D) An elevated CRP is diagnostic of a bacterial infection.

Question 56

Phenotypic methods of identifying microorganisms in a patient sample are characterized as those that ________.

A) directly examine the organism's appearance or behavior, which includes its metabolic abilities, environmental preferences and drug susceptibilities
B) analyze the genetic makeup of the microorganism, which conclusively diagnoses the infection
C) make use of the patient's antibodies to precipitate the microorganism out of solution, or agglutinate the antigens in the sample
D) make use of color-changing antibodies directed against the microbe that will become visible to the naked eye when bound

Question 57

The value of whole genome sequencing is that it can separate larger strands of DNA by slowly applying alternating voltage levels from three different directions.

Question 58

If a phenotypic analysis requires culturing the organism before testing can begin, this is problematic for two reasons; i) rapid diagnosis may be critical and culturing can take up to 24 hours, and ii) a successful in vitro culturing method for a specific pathogen may not be feasible.

Question 59

The CDC operates a national laboratory network called PulseNet, that compiles DNA fingerprinting data and connects foodborne illness cases so outbreaks can be detected rapidly.

Question 60

An outbreak of E. coli 0157:H7 was suspected to be associated with the petting zoo enclosure at the state fair. Epidemiologists with the CDC created a DNA fingerprint from the E. coli isolated from patients and compared it to bacterial isolates analyzed by national laboratories. They confirmed that the organism was indeed being transmitted by the animals at the fair. The CDC uses what method to generate these fingerprints?

A) PFGE
B) FISH
C) Microarray
D) Hybridization

Question 61

Which of the following can be determined from phenotypic assessment of the nasopharyngeal sample?

A) Cellular shape, size, and arrangement
B) The organism's DNA
C) The presence of antibodies
D) The organism's RNA

Question 62

The patient reports that he had a negative HIV PCR test about a month ago. What is the most appropriate interpretation of this information by the nurse?

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

Question 63

The lumbar puncture was especially uncomfortable for the patient. What step listed below is most important to be taken to ensure the procedure does not need to be repeated?

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 64

Analysis of the laboratory samples yield a diagnosis of herpes simplex virus. The patient's mother is upset, as she does not believe her son is sexually active. The nurse explains that the presence of HSV does not imply sexual contact and provides education about the accuracy of the results. Which of the following is the best rationale for confidence in the diagnosis?

A) Signs and symptoms are diagnostic.
B) PCR tests are highly sensitive and specific.
C) The Gram stain is an excellent screen for HSV.
D) HSV can be definitively identified by light microscopy.

Question 65

The patient's urine culture was collected using a clean-catch method. After inoculation and incubation, several organisms were identified in amounts that were reported as normal microbial flora. Which of the following statements by the student nurse indicates proper understanding of the findings?

A) The patient is superinfected and needs immediate antimicrobial treatment.
B) The specimen was contaminated 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 66

A Western blot test will be performed. The nurse educates the patient that the Western blot test has high sensitivity and specificity. Which of the following statements by the patient demonstrates understanding of this teaching?

A) A positive Western blot test may be a false-positive since the test has high specificity and may detect the presence of many antibodies.
B) The Western blot test is unlikely to generate a false-positive result. This will be used to confirm or refute the ELISA test results.
C) A positive Western blot may be a false-positive since the test has high sensitivity and may detect the presence of many antibodies.
D) The Western blot test may generate a false-positive result. A positive test will be confirmed by an HIV PCR.

Question 67

An ELISA test sent for HIV screening came back with a positive result. The nurse educates the patient that this test is highly sensitive with low specificity. Which of the following statements by the patient demonstrates understanding of this teaching?

A) It is possible that this is a false-positive result since the test may have been positive for something other than HIV.
B) It is unlikely that this is a false-positive result since the test is so specific it does not miss a positive result.
C) It is possible that this is a false-positive result since low specificity means the tests are less accurate.
D) It is unlikely that this is a false-positive result since it is highly sensitive.

Question 68

The patient's respiratory PCR results are reported as "insufficient cells available for testing." Which of the following statements by the student nurse indicates proper understanding of the findings?

A) The patient is free of infection since insufficient cells could be isolated.
B) A smaller sample must be sent, since the irrigation solution volume diluted the cells.
C) This is a very specific and sensitive finding that points to a viral infection.
D) The sample was inadequate, and the nasopharyngeal specimen collection must be repeated.

Question 69

What kind of data will the PCR results provide?

A) Biochemical characteristics
B) Immunologic information
C) Genotypic information
D) Microscopic morphology