Pharmacology Antimicrobial Therapy Principles 4

Question 1

Which mechanism of antibiotic resistance involves bacterial enzymes that chemically modify aminoglycosides?

Accepted Answer

Enzymatic inactivation

Answer

Aminoglycoside-modifying enzymes (acetyltransferases, phosphotransferases, nucleotidyltransferases) chemically alter the drug, reducing its binding to the ribosome.

Question 2

A patient with a severe penicillin allergy (anaphylaxis) needs treatment for a group A streptococcal infection. The best alternative is:

Accepted Answer

Clindamycin

Answer

Clindamycin is a safe alternative for group A streptococcal infections in patients with a history of severe penicillin allergy (anaphylaxis).

Question 3

Which PK/PD parameter best correlates with the efficacy of beta-lactam antibiotics?

Accepted Answer

Time above MIC (%T>MIC)

Answer

Beta-lactams exhibit time-dependent killing; efficacy is best predicted by the percentage of the dosing interval that free drug concentrations remain above the MIC.

Question 4

Extended-infusion (3–4 hour) beta-lactam administration is used primarily to optimize which PK/PD target?

Accepted Answer

T>MIC

Answer

Extended infusions increase the time free drug remains above MIC, optimizing the time-dependent killing characteristic of beta-lactams.

Question 5

A patient is diagnosed with VRE (vancomycin-resistant Enterococcus). Which antibiotic is approved for treating VRE infections?

Accepted Answer

Linezolid

Answer

Linezolid (an oxazolidinone) is FDA-approved for treatment of VRE faecium infections and is active regardless of vancomycin resistance.

Pharmacology Practice Test

Pharmacology Practice Test

Pharmacology Antimicrobial Therapy Principles 4