Question 1

All positive HIV- EIA tests must be confirmed by another independent test, usually the HIV Western blot.

Accepted Answer

All positive HIV EIA tests must be confirmed by another independent test, usually the HIV Western blot, to rule out false positives and confirm the presence of HIV antibodies.

Question 2

Advanced cases of AIDS may not give a positive EIA test.

Accepted Answer

Advanced cases of AIDS may have a weakened immune system that cannot produce enough antibodies to trigger a positive EIA test result. In such cases, alternative testing methods such as nucleic acid testing (NAT) may be done to detect the virus.

Question 3

When using the EIA test for HIV screening, both false negative and false positive results are possible.

Accepted Answer

The enzyme-linked immunosorbent assay (EIA) test for HIV screening may give false negative results if the person has not developed detectable levels of antibodies or if the sample was taken during the window period of infection. False positive results may occur due to cross-reactivity with other antibodies or with the protease inhibitors used in antiretroviral therapy. Confirmatory testing with Western blot or PCR is needed for accurate diagnosis.

Question 4

Urinary tract diseases are more common among females than they are in males.

Accepted Answer

Females have shorter urethras than males, which makes it easier for bacteria to travel up to the bladder and cause infections. This is why urinary tract diseases are more common among females.

Question 5

To detect antibodies in human serum, the direct EIA is most commonly employed.

Accepted Answer

The indirect EIA (Enzyme Immunoassay) is most commonly employed to detect antibodies in human serum, as it allows for amplification of the signal and is more versatile and sensitive compared to the direct EIA.

Question 6

Fluorescent antibodies can be used to separate mixtures of cells into relatively pure populations with a fluorescence cytometer.

Accepted Answer

Fluorescent antibodies can be conjugated to specific cell surface markers, allowing for the identification and isolation of specific cell populations using a fluorescence cytometer.

Question 7

At this time, EIA tests are too difficult for routine diagnoses.

Accepted Answer

EIA tests (enzyme immunoassay tests) are commonly used for diagnosing various infections and diseases such as HIV, hepatitis, and Lyme disease. They are relatively easy to perform and interpret compared to other diagnostic tests, such as Western blotting or PCR. Therefore, EIA tests are often included in routine diagnostic protocols.

Question 8

In the EIA test for HIV infection, the microtiter plate is coated with disrupted HIV particles.

Accepted Answer

In the EIA test for HIV infection, the microtiter plate is coated with disrupted HIV particles, which allows for the detection of antibodies to HIV in a patient's blood sample.

Question 9

The EIA test for HIV infection is a direct test for HIV envelope proteins.

Accepted Answer

The EIA (or ELISA) test detects antibodies produced by the body in response to HIV infection, not the virus itself or its envelope proteins.

Question 10

One of the problems encountered when using fluorescent and radioisotopically labeled monoclonal antibodies is the tedious culturing procedures that must be used.

Accepted Answer

The culturing procedures are required for producing the monoclonal antibodies, but the labeling process itself is not necessarily more tedious than other labeling methods.

Question 11

In cases of suspected foodborne or waterborne infections, fecal samples should be inoculated into a variety of selective media.

Accepted Answer

Fecal samples should be inoculated into a variety of selective media to isolate the causative agent of the infection. Different media may be selective for different types of bacteria or pathogens, allowing for a more accurate diagnosis.

Question 12

Discuss how recent advances in the molecular biology of nucleic acids have revolutionized methods used for the identification of infectious disease agents and how they are favored over traditional biochemical tests.

Accepted Answer

The answer of Discuss how recent advances in the molecular...

Question 13

Finding no bacterial growth, despite persistent urinary tract symptoms, indicates that the problem is likely either nonpathogenically physiological or psychosomatic.

Accepted Answer

The answer of Finding no bacterial growth, despite persistent urinary...

Question 14

Obligate anaerobic bacteria are often missed as the causal agents of infection in clinical diagnosis. Why is this so? Describe one method commonly used to culture these bacteria.

Accepted Answer

The answer of Obligate anaerobic bacteria are often missed as...

Question 15

Antibodies and antigens can be reported in mass units called antibiograms.

Accepted Answer

Antibodies and antigens are not reported in mass units called antibiograms. Antibiograms are used to report the susceptibility of bacteria to different antibiotics.

Question 16

What is the basis for inferring infection of a pathogen when a serological EIA is performed? In this context, what does a positive result indicate?

Accepted Answer

The answer of What is the basis for inferring infection...

Question 17

Nucleic acid probes and immunological reagents are not commonly used in the clinical laboratory for the diagnosis of viral disease, because the cultivation of the virus is often difficult or even impossible.

Accepted Answer

Nucleic acid probes and immunological reagents are commonly used in the clinical laboratory for the diagnosis of viral disease, despite the difficulty or impossibility of cultivating certain viruses.

Question 18

Hydrogen sulfide production is assayed by growth in a medium containing ferric iron (Fe3+).

Accepted Answer

Hydrogen sulfide production can be detected by a black precipitate that forms when ferrous sulfide (FeS) reacts with ferric iron (Fe3+) in the medium. This is known as the H2S-FeCl3 test or the lead acetate test.

Question 19

The causal agents of urinary tract diseases are often members of the normal flora.

Accepted Answer

Many urinary tract infections are caused by bacteria that normally live in the intestines, such as E. coli, which can travel up the urethra to the bladder and cause infection.

Question 20

Some infectious agents, such as Neisseria gonorrhoeae, do not elicit a systemic immune response.

Accepted Answer

Neisseria gonorrhoeae is known to evade the immune system by altering its surface antigens and thus does not elicit a strong systemic immune response.

Quiz 31: Diagnostic Microbiology and Immunology