Evaluating the Effect of Oxygen Concentrations on Antibiotic Sensitivity, Growth, and Biofilm Formation of Human Pathogens

Standard antimicrobial susceptibility tests are performed in vitro under normal room oxygen conditions to predict the in vivo effectiveness of antimicrobial therapy. The aim of this study was to conduct a comprehensive analysis of the effect of different oxygen levels on the antibiotic susceptibility of two strains of Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae. It was found that anoxic conditions caused reduced sensitivity of bacteria to aminoglycoside antibiotics in four of six bacteria used in the study. In addition, oxygen limitation decreased the susceptibility of P. aeruginosa strains and K. pneumoniae strains to piperacillin/tazobactam and azithromycin, respectively. In contrast, five of six bacteria became more susceptible to tetracycline antibiotics under oxygen-limiting conditions. Our data highlight the importance of considering the potential in vivo oxygen levels within the infection site when setting susceptibility breakpoints for evaluating the therapeutic potential of a drug and its effect on antibiotic sensitivity of the pathogen.