In vitro activity of Amphotericin B against zygomycetes isolated from deep mycoses: a comparative study between incubation in aerobic and hyperbaric atmosphere.

Many case reports suggest that the use of hyperbaric oxygen therapy associated with surgical and medical approaches may contribute to restricting the growth of zygomycetes in patient tissue. The primary aim of this study was to obtain data concerning the in vitro susceptibility of 22 zygomycetes to antifungals such as amphotericin B and posaconazole, and to compare the in vitro development of these fungi in aerobic normobaric versus hyperoxic normobaric and hyperbaric atmosphere. None of the zygomycetes grew after 24-hour and 72-hour incubation in a hyperoxic hyperbaric (2 or 3 ATA) atmosphere. However, when plates were maintained at room temperature in aerobic conditions, colonies were observed from 36-96 h after inoculation, while minimum inhibitory concentration (MIC) values remained the same. This preliminary in vitro study focuses on the in vitro examination of combination therapies to potentiate antifungal activity. Both hyperoxic hyperbaric conditions and a single antifungal agent, as well as combinations of different antifungal drugs were used. Results suggest an impressive in vitro fungistatic activity of the hyperoxic hyperbaric atmosphere, even if the antifungal effect is strictly time-dependent using these incubation conditions.