In a Kirby-Bauer susceptibility test, the presence of a zone of inhibition around disks containing antimicrobial agents indicates __________ .


a. that the microbe does not grow in the presence of the agents
b. that the microbe grows well in the presence of the agents
c. the smallest amount of the agent that will inhibit the growth of the microbe
d. the minimum amount of an agent that kills the microbe in question

Drugs that act against protein synthesis include ___________ .

a. beta-lactams

b. trimethoprim

c. polymyxin

d. aminoglycosides

Why are alcohols more effective in a 70% solution than in a 100% solution?

Contrast the structures and actions of soaps and quats.

Diffusion and dilution tests that expose pathogens to antimicrobials are designed to determine __________ .

a. the spectrum of action of a drug

b. which drug is most effective against a particular pathogen

c. the amount of a drug to use against a particular pathogen

d. both b and c

The key to successful chemotherapy is __________ .

a. selective toxicity

b. a diffusion test

c. the minimum inhibitory concentration test

d. the spectrum of action

Which of the following statements is relevant in explaining why sulfonamides are effective?

a. Sulfonamides attach to sterol lipids in the pathogen, disrupt the membranes, and lyse the cells.

b. Sulfonamides prevent the incorporation of amino acids into polypeptide chains.

c. Humans and microbes use PABA differently in their metabolism.

d. Sulfonamides inhibit DNA replication in both pathogens and human cells.

Support or refute the following statement: Antimicrobial agents make cells become resistant.

A man has been given a broad-spectrum antibiotic for his stomach ulcer. What unintended consequences could arise from this therapy?