ESBL-producing bacteria show resistance to which class of antibiotics?

• A. Macrolides
• B. Aminoglycosides
• C. Beta-lactam antibiotics
• D. Quinolones

Answer: (C)

ESBLs are enzymes that break the beta-lactam ring, so bacteria that produce them become resistant to antibiotics in the beta-lactam class. This includes penicillins and cephalosporins, and aztreonam as well. Carbapenems often remain active against many ESBL producers, though resistance can occur with some strains. The other antibiotic classes—macrolides, aminoglycosides, and quinolones—are not inactivated by these enzymes, so ESBL production specifically drives resistance to beta-lactam drugs rather than those other classes.