Extended spectrum beta-lactamase (ESBL) resistance confers resistance to most beta-lactam antibiotics. What is an example of a beta-lactam antibiotic?

• A. Amoxicillin
• B. Cefazolin
• C. Cefoxitin
• D. Erythromycin

Answer: (C)

Beta-lactam antibiotics all contain the beta-lactam ring, and ESBL enzymes break that ring, causing resistance to many drugs in this class. Cefoxitin is a beta-lactam antibiotic in the cephamycin family. Cephamycins are structurally different enough that they are generally more resistant to ESBL hydrolysis than other beta-lactams, so it serves as the example of a beta-lactam in this context. The other options include a penicillin (also a beta-lactam) and a first-generation cephalosporin (both typically inactivated by ESBLs), while erythromycin is not a beta-lactam at all.