Combined effects of hyperbaric oxygen and antifungal agents on the growth of Candida albicans.

The effects of hyperbaric oxygen (HBO) and antifungal agents on Candida albicans were studied. Growth curves at O2 tensions of 160 mm Hg, 900 mm Hg, and 1800 mm Hg for prolonged exposures showed no effect of pressure alone. There was a significant dose response to increasing O2 tension; growth inhibition occurred at 900 mm Hg O2 and killing at 1800 mm Hg O2. Minimum inhibitory concentrations (MIC) and minimum cidal concentrations (MCC) at 160 and 900 mm Hg O2 were done using amphotericin B, nystatin, clotrimazole, miconazole, ketoconazole and 5-fluorocytosine. MIC and MCC's were done with amphotericin B at 90-min exposures to 1800 mm Hg O2. There was no enhancement of MIC or MCC at 900 mm Hg O2. However, ketoconazole was ineffective at killing at 900 mm Hg O2 indicating a protective effect of HBO with this drug. Oxygen tensions of 1800 mm Hg for 90 min in the presence of amphotericin B showed an enhancement of both MIC and MCC. Closer quantitation of this effect upon the in vitro growth and survival of the organism showed an additive but not synergistic effect.