Antibiotic resistance in clinical isolates of Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus does not impact sensitivity to human beta defensin 4

Antibiotic usage is essential for infection control but hastens emergence of antibiotic resistant microbes. In particular, Acinetobacter baumannii is an important pathogen because of its heightened ability to acquire drug resistance. The need for novel antibacterial agents led us to evaluate the sensitivity of drug-resistant bacteria to the antimicrobial activity of human beta defensin 4 (HBD-4). Clinical isolates of A. baumannii (N = 14), Pseudomonas aeruginosa (N = 15), and Staphylococcus aureus (N = 20), including 10 methicillin-resistant (MRSA) isolates, were examined. All bacterial strains were susceptible to HBD-4 antimicrobial activity, with no correlation between antibiotic resistance and HBD-4 sensitivity. The results demonstrate that antibiotic resistant microorganisms, including MRSA, can be inhibited by HBD-4, which may represent an effective therapeutic agent for infections involving drug-resistant microorganisms.