Anti-infective Medications Practice Test

Bacteria resist beta-lactam antibiotics by producing an enzyme that inactivates the drug. Beta-lactamase hydrolyzes the beta-lactam ring found in penicillins and cephalosporins, destroying the chemical structure needed for the antibiotic to bind its target penicillin-binding proteins. With the ring opened, the drug can’t block cell-wall synthesis, so the bacteria survive. This resistance mechanism is common and can spread between bacteria via plasmids, increasing the challenge of treatment. Other enzymes listed—amylase, protease, and lipase—digest starch, proteins, and fats, respectively, and do not confer antibiotic resistance.