Hyperbaric hyperoxia suppresses growth of Staphyloccus aureus, including methicillin-resistant strains

Purpose. We investigated the effects of increased oxygen tension on the in vitro growth of Staphylococcus aureus (MRSA), methicillin-sensitive Staphylococcus aureus (MSSA), and Escherichia coli (E. coli). Methods. The effects of oxygen tension [normobaric normoxia (21% O₂ at 1 atm), normobaric hyperoxia (100% O₂ at 1 atm), hyperbaric normoxia (21% O₂ at 2 atm), and hyperbaric hyperoxia (100% O₂ at 2 atm) on the in vitro growth of MRSA, MSSA, and E. coli were investigated by population analysis. Results. Compared with normobaric normoxia, a 90-min exposure to hyperbaric hyperoxia significantly inhibited growth of both MRSA (by 25.0 ± 3.0%, mean ± SEM; P < 0.01) and MSSA (by 24.0 ± 3.3%; P < 0.01). Normobaric hyperoxia and hyperbaric normoxia were without effect. In contrast, the growth of E. coli was not affected by any of the above treatments. Conclusion. Our results indicate that the bacterium S. aureus, including resistant strains, is susceptible to oxygen stress. The observation that relatively brief (90-min) treatment with hyperbaric hyperoxia is sufficient to produce significant growth inhibition suggests that hyperbaric hyperoxia may be useful in the treatment of serious staphylococcal infections.