Deck 17: Procedures for Identifying Pathogens and Diagnosing Infections

Question 1

Which of the following is not a biochemical test used to identify a pathogen?

A)acid-fast reaction
B)hydrolysis of gelatin
C)coagulase production
D)indole production
E)carbohydrate fermentation

Answer 1

A

Question 2

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

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

Answer 2

C

Question 3

Soluble antigens are detected in which type of test?

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

Answer 3

C

Question 4

Which of the following is incorrect regarding the complement fixation test?

A)First antigen and antibody are allowed to react.
B)Purified complement proteins are added to the antigen-antibody tube.
C)Sheep red blood cells are added to the antigen-antibody-complement mixture.
D)Hemolysis of the sheep red blood cells occurs in a positive test result.

Question 5

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

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

Question 6

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

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

Question 7

Which of the following choices are true about the dyes fluorescein and rhodamine?

A)They can be used to label antibodies in immunofluorescence tests.
B)They emit visible light in response to ultraviolet radiation.
C)They are observed in the fluorescent microscope.
D)They are used to identify pathogens of chlamydiosis, Legionnaires'disease, and others.
E)All of these choices are correct.

Question 8

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 antigen that produces a visible reaction.
D)the Western Blot method.

Question 9

Whole antigens are detected in which type of test?

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

Question 10

Which of the following methods is categorized as a direct test in order to analyze a specimen?

A)catalase test
B)Gram stain
C)phage typing
D)antimicrobic sensitivity
E)production of gas

Question 11

When serum proteins are separated by electrophoresis and then antibodies specific for the serum proteins are placed in a parallel trough in order to form reaction arcs for each protein, the test is called

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

Question 12

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

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

Question 13

Serotyping of the 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 14

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 15

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)the Quellung test

Question 16

In lab, a student observes some dull, wrinkled brown colonies growing on their agar.They Gram stain the sample and observe single bacilli.Their blood agar does not reveal any hemolysis while their MSA has growth and fermentation.Using the following table and the given observations, determine which microorganism this would most likely be.
$$\begin{array} { | l | l | l | } \hline \text { Bacilli } & \text { B. cereus } & \text { B. subtilis } \\\hline \text { Colony morphology } & \text { Dull, frosted colonies } & \begin{array} { l } \text { Dull, wrinkled colonies cream to } \\\text { brown colors }\end{array} \\\hline \text { Microscopic arrangement } & \text { Chains } & \text { Single bacilli } \\\hline \text { Catalase } & + & + \\\hline \text { Blood agar } & \text { Beta } & \text { Gamma } \\\hline \text { Mannitol salt agar } & -& + \text { growth and } + \text { fermentation } \\\hline\end{array}$$
$\begin{array}{|l|r|}\hline \text { Pseudomonas }&\text { P. aeruginosa }\\\hline \text { Catalase }&+\\\hline\text { Oxidase }&+\\\hline\text { Motile }&+\\\hline\text { Blood agar }&\text { Beta }\\\hline\text { Glucose fermentation }&+\\\hline\text { Escherichia }&\text { E. coli }\\\hline\text { Lactose fermentation }&+\\\hline\text { Motile }&+\\\hline\text { Citrate fermentation }&-\\\hline\text { Urease }&-\\\hline\text { Catalase }&+\\\hline\end{array}$

A)E.coli
B)Pseudomonas aeruginosa
C)B.subtilis
D)B.cereus

Question 17

All of the following are methods to diagnose viral infections, except

A)detection of viral nucleic acid using specific probes.
B)Western Blot.
C)cells taken from patient are examined for evidence of viral infection.
D)signs and symptoms.
E)the light microscope.

Question 18

Affixing antigen to an inert particle such as a latex bead is sometimes used in which type of test?

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

Question 19

Which technique used to diagnose a disease is also called the double diffusion method?

A)Ouchterlony test
B)VDRL test
C)immunoelectrophoresis
D)Western Blot
E)ELISA

Question 20

A physician orders an antistreptolysin O (ASO) titer test to check for rheumatic fever.A patient serum sample is exposed to known suspensions of streptolysin and then allowed to incubate with RBCs.If the patient does have rheumatic fever, what will happen?

A)Not enough information is provided to speculate.
B)The red blood cells will lyse.
C)The red blood cells will agglutinate only.
D)The red blood cells will not lyse.
E)The red blood cells will fluoresce.

Question 21

Serological tests should have low sensitivity and specificity.

Question 22

Which test is used to measure the IgE present in allergic patients?

A)fluorescent antibody tests
B)Rapid Plasma Reagin (RPR) test
C)Weil-Felix reaction
D)RIST
E)ELISA

Question 23

ELISA tests use a fluorescent dye as a label to trace antigen-antibody reactions.

Question 24

All of the following are routine biochemical tests to aid in identifying a species, except

A)motility.
B)carbohydrate fermentation.
C)catalase test.
D)oxidase test.
E)coagulase test.

Question 25

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

Question 26

The Widal test is used for diagnosing salmonellosis.

Question 27

Some diseases are diagnosed without the need to identify microbes from a patient specimen.

Question 28

The more a sample can be diluted and yet still react with antigen, the ______ the concentration of antibodies in that sample and the _______ is its titer.

A)lower; lower
B)higher; lower
C)lower; higher
D)higher; higher

Question 29

All of the following are correct about the indirect ELISA, except

A)it can detect antibodies in a serum sample.
B)it is the common screening test for antibodies to Helicobacter.
C)color development indicates that antibody was not present in the patient's serum.
D)it is the common screening test for antibodies to Hepatitis A.
E)a known antigen is adsorbed to the surface of a well.

Question 30

Sputum is obtained by

A)swabbing the mouth to sample saliva.
B)a clean catch urine sample.
C)the patient coughing up mucus from the lower respiratory system.
D)a spinal tap above the chest.
E)a throat swab.

Question 31

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

Question 32

Broad general characteristics of bacteria on flowcharts can be misleading for a diagnosis of disease.

Question 33

Serological testing always involves reactions between specific antibody and antigen.

Question 34

An antibody_____ provides a measure of the quantity of antibodies in the serum.

Question 35

A rising antibody titer a few days apart indicates

A)the patient had a past case of the disease.
B)the patient has a current infection.
C)nothing, people always have antibodies in their serum.
D)All of these choices are correct.

Question 36

The indirect ELISA test detects ______ in a patient's blood.

A)antigen
B)antibody
C)microorganisms
D)IgE only
E)complement

Question 37

Maggie was told she has a positive titer to measles.Which of the following could explain this?

A)She was vaccinated against measles.
B)She had measles sometime in her life.
C)She has measles now.
D)The test was a false positive.
E)All of these choices are correct.

Question 38

Mary had an accidental needlestick one night during her shift as an emergency medical technician.Initially, she tested positive for HIV by the ELISA test.Which test would be done next to confirm an HIV infection?

A)immunoelectrophoresis
B)Ouchterlony
C)complement fixation
D)Western Blot
E)radioimmunoassay

Question 39

Test systems involving which of the following has greatly improved the specificity of immunological tests?

A)Monoclonal antibodies
B)Electronics
C)Enzymes
D)Radioactivity
E)All of these choices are correct.

Question 40

In direct antigen testing, the reaction is generally seen with the

A)electron microscope.
B)naked eye.
C)light microscope.
D)API 20E miniature identification system.
E)PCR reaction.

Question 41

If trying to isolate a specific pathogen from amongst a variety of normal microbiota, which type of media would be most helpful?

A)nutrient agar
B)differential media
C)blood agar
D)selective and differential agar

Question 42

Compare and contrast agglutination and precipitation reactions, and include a description of one test for each type of reaction.

Question 43

Select the methods below that can be used for identifying the causative agent of a viral infection.Check all that apply.

A)cultivation of the virus from patient samples in cell/tissue cultures
B)detection of antibodies to the virus in a patient's serum
C)observation of the patient's symptoms
D)gram stain of patient specimens
E)amplification and detection of viral nucleic acid in patient specimens
F)culture of virus from patient specimens in enriched agar and broth media
G)direct observation of viral-infected cells using fluorescent-antibody staining

Question 44

Minute amounts of a pathogen in a patient sample can be rapidly detected by specifically amplifying and identifying its nucleic acid using PCR.This is an example of

A)an immunologic method.
B)a microscopic method.
C)a phenotypic method.
D)a genetic method.

Question 45

Biochemical testing used for identification of pathogens involves each of the following, except

A)inoculation of additional media, incubation, and observation for a color change.
B)quick tests that take just a few seconds.
C)examining organisms through the microscope.

Question 46

In _________ tests, antibody cross-links whole-cell antigens, forming complexes that settle out and form visible clumps in the test chamber.

Question 47

Describe the indirect ELISA test that is used as a screening test for HIV (AIDS) and include the following: a) sequence of procedures, b) reagents used, and c) detection and interpretation of a positive test.

Question 48

When collecting __________, a "clean catch" method is often used.

Question 49

Identify, describe, and discuss the objectives of the three main categories of identifying infectious agents using specific examples.

Question 50

In a __________, antigens or antibodies are labeled with radioactive isotopes and traced.

Question 51

Culture of patient specimens to detect pathogens is usually done on blood agar plates only.

Question 52

In indirect fluorescent testing, fluorescent _____ are used to react with the Fc region of another, specific, serum antibody.

Question 53

Allergy testing, which is accomplished by injecting tiny amounts of allergen into the skin and examining the injection site for a reaction, is an example of an in vitro test.

Question 54

Which of the following can be used for the cultivation of viruses?

A)Enriched broth media
B)Viral host cells grown in vitro
C)Enriched agar media
D)All of these choices.

Question 55

Why do many physicians feel that stool cultures are not necessary, except in certain circumstances when diagnosing GI tract infections?

Question 56

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

Question 57

Pulsed-field gel electrophoresis (PFGE) is often used to determine whether bacterial isolates from different cases of food-borne illness are the same and can be traced to the same source.This is an example of

A)an immunologic technique.
B)a genetic method.
C)a phenotypic method.
D)a microscopic technique.

Question 58

Tests that take place in the lab, such as in a test tube or Petri-dish, outside of a living host, are referred to as _______________ whereas tests that take place in a living host, such as in a patient, are described as ______________.

A)In loco; In vitro
B)In vitro; In loco
C)In vitro; In vivo
D)In loco; In vivo

Question 59

Describe three possible sampling sites and methods of collection for clinical laboratories.