Chapter 10

What major cellular feature that might be targeted by antimicrobial drugs is found in both bacteria and fungi, but not in humans?
A. Lipopolysacccharide
B. Ribosomes
C. Cell wall
D. RNA polymerase

What effect does penicillin have on susceptible bacterial cells?

Sulfonamide drugs inhibit microbial growth by disrupting metabolic pathways. What general mechanism do these drugs use?

How does resistance to drugs spread in bacterial populations?
A. Exposure to drugs cause mutations in bacterial genes
B. Horizontal gene transfer between bacteria spread resistance (R) plasmids
C. Exposure to drugs alters gene expression in bacteria

Some bacterial cells are resistant to a variety of antimicrobials because they actively pump the drugs out of the cell. (TRUE/FALSE)

The therapeutic window of an anitmicrobial is the:
A. Ratio of the dose a patient can tolerate to the effective dose
B. Ratio of the concentration at which the antibiotic is both effective and non-toxic
C. Range of microorganisms the antimicrobial effects

A (bacteriocidal or bacteriostatic or inhibitory) concentration of a drug is one at which microbes survive but are not able to grow and reproduce.

The outer membrane of Gram-negative bacteria enables many antimicrobial drugs to enter the cell more easily.
(TRUE/FALSE)

Antisense nucleic acids interfere with protein synthesis.
(TRUE/FALSE)

Drug-resistant populations of microbes arise when:
A) synergy between medications occurs.
B) exposure to drugs selectively kills sensitive cells, allowing overgrowth of resistant cells.
C) exposure to drugs causes mutations that produce resistance.
D) resistant cells become numerous in a population due to their greater vigor.
E) the patient becomes immune to the drug.

Methicillin is an example of the beta-lactam class of drugs that:
A) inhibits cell wall synthesis.
B) inhibits protein synthesis.
C) inhibits metabolic pathways.
D) inhibits nucleic acid synthesis.
E) disrupts cytoplasmic membranes.

The tetracyclines interfere with:
A) nucleic acid synthesis
B) cell wall synthesis
C) cell membrane component synthesis
D) folic acid synthesis
E) protein synthesis

How does resistance to drugs spread in bacterial populations?
A) Exposure to drugs induces immunity.
B) Exposure to drugs causes mutations in bacterial genes.
C) Horizontal gene transfer between bacteria spreads R (resistance) plasmids.
D) Exposure to drugs alters gene expression in bacteria.
E) Genetic recombination during sexual reproduction.

The antifungals known as polyenes interact with ________, a lipid unique to fungus membranes.
A) mycolic acid
B) glycolic acid
C) cholesterol
D) ergosterol
E) phospholipid

Disruption of the normal microbiota can result in infections caused by which of the following microbes?
A) Mycobacterium
B) both Candida albicans and Clostridium difficile
C) Clostridium difficile
D) Streptococcus
E) Candida albicans

An antimicrobial is described as preventing alanine-alanine bridge formation. This means it:
A) blocks glycocalyx synthesis.
B) prevents folic acid synthesis.
C) interferes with cytoplasmic membrane synthesis.
D) interferes with protein synthesis.
E) prevents cell wall synthesis in bacteria.

The therapeutic window of an antimicrobial is the:
A) length of time the medication persists in the body after a single dose.
B) range of concentrations at which the antimicrobial is both effective and non-toxic.
C) range of microorganisms the antimicrobial effects.
D) ratio of the concentration of antimicrobial in the blood to the oral dose.
E) ratio of the dose a patient can tolerate to the effective dose.

Which of the following statements is true of selective toxicity?
A) Selective toxicity takes advantage of structural similarities between host and pathogen.
B) Selective toxicity takes advantage of structural and/or metabolic differences between host and pathogen.
C) To be effective, an antimicrobial agent must be more toxic to the patient than the pathogen.
D) Selective toxicity takes advantage of differences in metabolic rates of the host and pathogen.
E) Selective toxicity damages only pathogenic bacteria and not beneficial bacteria.

Which of the following drugs inhibits nucleic acid synthesis specifically in most bacteria?
A) rifampin
B) tetracycline
C) actinomycin
D) 5-fluorocytosine
E) fluoroquinolones

A drug is structurally similar to PABA and inhibits folic acid synthesis. It is most likely a(n):
A) nucleic acid analog.
B) sulfonamide.
C) penicillin
D) tetracycline
E) azole

Many drugs that inhibit the synthesis of the cell wall act by:
A) preventing the formation of β-lactamases.
B) disrupting the formation of the mycolic acid layer of the cell wall.
C) blocking the secretion of cell wall molecules from the cytoplasm.
D) preventing the formation of alanine-alanine bridges.
E) preventing the cross-linkage of NAM subunits.

Most broad-spectrum antibiotics act by:
A) inhibiting nucleic acid synthesis.
B) inhibiting the synthesis of the cell wall.
C) inhibiting metabolic pathways.
D) disrupting the cytoplasmic membrane.
E) inhibiting protein synthesis.

Which of the following is a primary advantage of semisynthetic drugs?
A) They are not readily absorbed.
B) They are less stable and consequently have fewer side effects.
C) They must be administered intravenously.
D) They are more effective than the unmodified natural antibiotics.
E) They work faster.

The topical drug ________ inhibits protein synthesis in Gram-positive bacteria by preventing loading of isoleucine onto tRNA.
A) Ciprofloxacin
B) Bacitracin
C) Amphotericin B
D) Tetracycline
E) Mupirocin

Which of the following can result when antibiotic therapy disrupts the normal microbiota?
A) both pseudomembranous colitis and thrush
B) thrush
C) pseudomembranous colitis
D) black hairy tongue
E) anaphylactic shock

Some bacteria are resistant to erythromycin as a result of mutation of their ribosomal RNA. What type of resistance does this represent?
A) change in the permeability of the drug
B) inactivation of the drug
C) alteration of the target of the drug
D) removal of the drug via a pump
E) overproduction of an enzyme in a key metabolic pathway