Question 1

How is drug-resistant Neisseria gonorrhoeae treated?

Accepted Answer

Drug-resistant Neisseria gonorrhoeae is treated with penicillinase-resistant β-lactams such as ceftriaxone or cefixime. Tetracycline and synthetic analogs of tetracycline are no longer recommended due to resistance, and vancomycin does not treat gonorrhea.

Question 2

Protein A has a strong affinity for

Accepted Answer

Protein A is a bacterial protein that has a strong affinity for antibodies, specifically the Fc region of immunoglobulin G (IgG) antibodies. This property is often used in biotechnology research and medicine to purify and detect IgG antibodies.

Question 3

A positive antibody titer indicates

Accepted Answer

A positive antibody titer indicates that the individual has been exposed to the antigen, whether through vaccination or previous infection, and has mounted an immune response to it. It does not necessarily indicate active infection or disease, nor does it indicate overall health status.

Question 4

Which of the following antibiotics inhibits RNA synthesis?

Accepted Answer

Rifampin inhibits RNA synthesis by binding to the beta subunit of bacterial RNA polymerase, preventing transcription. The other antibiotics listed have different modes of action. Penicillin interferes with cell wall synthesis, erythromycin inhibits protein synthesis, and azithromycin also inhibits protein synthesis but through a different mechanism than erythromycin.

Question 5

Indirect EIA is used to detect

Accepted Answer

Indirect EIA is used to detect antibodies. It relies on the principle of detecting an antigen-antibody reaction by adding a labeled antibody specific to the target antigen, which binds to any antigen-antibody complexes formed in the sample being tested. The labeled antibody is usually linked to an enzyme, which generates a colored or fluorescent signal that can be detected and quantified.

Question 6

________ is used to monitor gene expression of a pathogen.

Accepted Answer

Reverse transcription PCR is commonly used to monitor gene expression of a pathogen by converting RNA to complementary DNA (cDNA) for amplification and detection of specific genes. Serology, antigen capture assay, and qualitative PCR are other assays used for pathogen detection and characterization, but they may not specifically measure gene expression.

Question 7

SYBR Green,commonly used in qPCR,binds nonspecifically to

Accepted Answer

SYBR Green binds specifically to double-stranded DNA, making it a commonly used dye in qPCR for DNA detection and quantification. It does not bind to single-stranded DNA or RNA.

Question 8

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

Accepted Answer

Hydrogen sulfide production is commonly assayed by growth in a medium containing ferric iron, which reacts with H2S to form a black precipitate of ferrous sulfide (FeS). This is a common test used in microbiology for the identification of sulfur-reducing bacteria.

Question 9

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

Accepted Answer

Many of the bacteria that cause urinary tract infections are part of the normal flora of the gastrointestinal tract, vagina, and periurethral areas. However, factors such as an imbalance in the normal flora, urinary tract obstructions, and weakened immune system can contribute to the development of urinary tract diseases.

Question 10

In the United States,every clinical and research institution requires that workers be protected from ________ that is contracted almost exclusively from handling patient specimens (rather than from known exposure or accidents).

Accepted Answer

Hepatitis B is commonly transmitted through exposure to blood and bodily fluids, including handling patient specimens. Therefore, clinical and research institutions require workers to be protected from this virus. The other options are also important infectious agents to protect against, but they are usually not contracted almost exclusively from handling patient specimens.

Question 11

Methylene blue in EMB agar is selective for

Accepted Answer

Methylene blue in EMB agar is selective for gram-negative bacteria. The dye inhibits the growth of gram-positive bacteria and allows only gram-negative bacteria to grow on the agar, which forms distinctive colonies.

Question 12

The use of selected culture media and incubation conditions to isolate microorganisms from samples is known as a(n)

Accepted Answer

The answer of The use of selected culture media and...

Question 13

A mechanism for penicillin resistance in bacteria is

Accepted Answer

Penicillin resistance in bacteria is often related to the production of β-lactamase enzymes that cleave the β-lactam ring of the antibiotic, rendering it inactive. This process prevents the antibiotic from inhibiting the synthesis of cell walls in the bacteria, allowing them to survive and proliferate.

Question 14

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

Accepted Answer

The EIA (Enzyme Immunoassay) test for HIV infection is an indirect test that detects antibodies produced by the body in response to HIV infection, not the HIV envelope proteins themselves.

Question 15

An important intestinal pathogen generally acquired from contaminated food or water is

Accepted Answer

Escherichia coli O157:H7 is an important intestinal pathogen that can cause severe diarrheal illness and is commonly acquired from contaminated food or water. Clostridium perfringens is also a foodborne pathogen, but is less commonly associated with intestinal disease, while Mycobacterium tuberculosis and Ebola virus are not primarily intestinal pathogens.

Question 16

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

Accepted Answer

Fecal samples of suspected foodborne or waterborne infections should be inoculated into a variety of selective media to detect and isolate the causative microorganisms present in the sample. Different selective media are used to support the growth of specific types of microorganisms and suppress the growth of unwanted microorganisms. This approach helps in the accurate identification of the infectious agent and is crucial for the proper diagnosis and treatment of the infection.

Question 17

The study of antigen-antibody reactions is known as

Accepted Answer

The study of antigen-antibody reactions is known as serology. Serology involves the detection, measurement, and identification of antibodies and other immune system components in body fluids. Immunology is a broader field that includes the study of the immune system, including its development, function, and disorders. Toxicology is the study of the effects of toxins and poisons on living organisms, while epidemiology is the study of the distribution and determinants of health and disease in populations.

Question 18

Obligately anaerobic normal flora are found in ________,which is an/are anoxic habitat(s)of the body.

Accepted Answer

Obligately anaerobic normal flora are found in portions of the oral cavity, which is an anoxic habitat of the body. The kidneys, skin, and lungs are not anoxic habitats.

Question 19

Hybridization requires a nucleic acid probe that binds to DNA or RNA of interest,which must be in the ________ form for hybridization to occur.

Accepted Answer

Hybridization requires a single-stranded nucleic acid probe to bind to its complementary DNA or RNA sequence. This pairing forms a stable hybrid or double-stranded structure that can be detected and analyzed.

Question 20

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

Accepted Answer

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

Quiz 27: Diagnostic Microbiology