In vitro survival of human pathogenic fungi in seawater.

The survival of propagules from 4 pathogenic fungi, Trichophyton mentagrophytes, Trichosporon cutaneum, Candida albicans, and Microsporum gypseum was studied in seawater subjected to different temperature (20--35 degrees C) and salinity (6--50%) levels in diurnal rhythm of 12 h cycles. Survival was measured by viability of propagules over a period of 52 weeks. All fungi, except T. cutaneum at 35 degrees C survived the experimental conditions for 52 weeks. Temperature was the most influential factor. When temperature increased, M. gypseum responded with enhanced viability whereas survival for C. albicans and T. cutaneum was inhibited. At 35 degrees C, T. cutaneum was not viable after 6--7 weeks even though it survived the initial 5 weeks with less loss of viability than the other test organisms. No correlation was seen between salinity level and loss of viability. Diurnal light had an inhibitory effect on T. cutaneum and C. albicans survival under in vitro conditions approximating those of seawater in Hawaii. M. gypseum had the highest level of survival over 52 weeks under usual in situ conditions simulated in vitro, followed by T. mentagrophytes, T. cutaneum, and C. albicans. Survival for 52 weeks even when salinity and temperature levels exceed those of the natural habitat indicates that seawater which washes sand beaches can be an environmental niche for potentially pathogenic fungi.