Success! In Clinical Laboratory Science – Bacteriology Practice Test 2026 - Free Bacteriology Practice Questions and Study Guide

Beta-lactamase enzymes produced by Haemophilus influenzae break the beta-lactam ring in penicillin, inactivating the drug. Because of this, beta-lactam antibiotics like penicillin are ineffective against these strains. The other drugs listed are not beta-lactams, so their activity isn’t directly compromised by beta-lactamase, though resistance can occur through other mechanisms. Clinically, this means infections with these bacteria are commonly resistant to penicillin but may respond to beta-lactamase inhibitor combinations or to non-beta-lactam antibiotics.