Comparison ofin Situ andin Vitro survival ofCandida albicans in seawater

The survival in seawater of several laboratory and field isolates ofCandida albicans was investigated. Initial studies were madein vitro (flasks) to confirm previous reports. Frequent sampling of viable cells showed that flask experiments, even repeated, produced varied patterns of survival in this closed system. As an alternative, multiple experiments were run in untreated seawater in dialysis bags and plexiglas chambers at ambient temperature (17‡ to 22‡C) in flowing seawater. Die-off rates of all cultures tested in dialysis bags were very rapid in the first day and may have been related to high levels of dissolved organic carbon in the tubing. Distilled water-or acid-washed bags did not yield significantly higher survival rates in all cases. When plexiglas chambers closed with Nuclepore membranes were used, survival rates decreased to 5% to 15% of the original population after 6 days. Chamber data were more uniform and represented approximately a twofold increase in survival over that shown previously inin vitro (flask) studies. Some evidence was obtained in all three test systems for the greater survival rate of a field isolate ofC. albicans compared with that noted for a laboratory (ATCC) strain. The results are considered to more accurately depict the survival ofC. albicans in summer temperate recreational waters.