11. Controlling Microbial Growth

Which of the following chemical agents is a gas? 

You and your classmates are trying to determine how a disinfectant might kill cells. You observe that when you spill the disinfectant in a tube of reduced litmus milk, the litmus turns blue again. You suggest to your classmates that

a. the disinfectant might inhibit cell wall synthesis.

b. the disinfectant might oxidize molecules.

c. the disinfectant might inhibit protein synthesis.

d. the disinfectant might denature proteins.

e. the disinfectant might damage DNA.

DRAW IT Show where the following antibiotics work: ciprofloxacin, tetracycline, streptomycin, vancomycin, polymyxin B, sulfanilamide, rifampin, erythromycin.

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Why does a cell die from the following antimicrobial actions?

a. Colistimethate binds to phospholipids.

b. Kanamycin binds to 70S ribosomes.

How does each of the following inhibit translation?

a. chloramphenicol

b. erythromycin

c. tetracycline

d. streptomycin

e. oxazolidinone

f. streptogramin

NAME IT This microorganism is not susceptible to antibiotics or neuromuscular blocks, but is susceptible to protease inhibitors.

Which of the following pairs is mismatched?

a. antihelminthic—inhibition of oxidative phosphorylation

b. antihelminthic—inhibition of cell wall synthesis

c. antifungal—injury to plasma membrane

d. antifungal—inhibition of mitosis

e. antiviral—inhibition of DNA synthesis

Match the antimicrobial drug class to its action. You may assign more than one drug class to a given action and some actions may not be applicable. <IMAGE>

A patient has an uncomplicated infection with a Gram-negative bacterium. He also has a history of penicillin allergy. Which drug is the best treatment option for this patient? (NCLEX/HESI/TEAS)

a. Ampicillin

b. A first-generation cephalosporin

c. A carbapenem

d. Isoniazid

e. Azithromycin

Which drug family would be the most effective to treat a patient diagnosed with a MRSA infection? (NCLEX/HESI/TEAS)

a. Penicillins

b. Third-generation cephalosporins

c. Carbapenems

d. Lincosamides

e. Aminoglycosides

Choose the false statement(s). Select all that apply. (NCLEX/HESI/TEAS)

a. Antifungal drugs may target cholesterol in fungal cell membranes.

b. Azole and polyene drugs promote cell lysis by impacting fungal cell plasma membranes.

c. Echinocandin drugs inhibit fungal cell wall synthesis.

d. Antifungal drugs may target DNA replication.

e. Antifungal drugs may target protein synthesis.

What advantages might a semisynthetic antimicrobial drug have over an antibiotic?

Match the antimicrobial drug to its feature. Some features may be used more than once, and some may not be used at all.

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Choose the true statement(s) about therapeutic index (TI). Select all that apply. (NCLEX/HESI/TEAS)

a. A drug with a high therapeutic index would be effective above the dose at which it is potentially toxic.

b. A narrow TI is preferable.

c. A drug for which the maximum safe dose is close to the minimum effective dose would have a high TI.

d. It is one measure of a drug’s general safety.

e. A drug that is not selectively toxic would most likely have a high TI.

Which of the following antimicrobial properties would be the most crucial to consider in developing a new antimicrobial? (NCLEX/HESI/TEAS)

a. Selective toxicity

b. Ease of administration

c. Lack of drug interactions

d. Long half-life

e. The drug’s capacity to be bactericidal