Effect of abscess fluid supernatants on the kinetics of Candida albicans growth

Abscess fluid supernatants have been found to inhibit microbial growth, an effect that appears to be due to a protein originating in the cytoplasm of neutrophils. The antimicrobial activity of calprotectin, the responsible protein, is reversible by the addition of zinc to the culture medium. To more carefully analyze this type of antimicrobial activity supernatants of fluids from experimental subcutaneous Candida albicans abscesses in mice were studied to determine how they affect the in vitro growth kinetics of C. albicans. The abscess fluid supernatants inhibited growth in a dose-dependent fashion and more at early times than at later ones. Instability of the abscess fluid antimicrobial activity did not appear to explain the timing of the growth inhibition. A marked lengthening of the lag phase of growth was observed in cultures containing the supernatants (from approximately 6 hr in the control cultures to 15-20 hr in those with the supernatants). On the other hand, the abscess fluid supernatants had only minimal effects on the generation times of actively proliferating C. albicans yeast cells. In addition, these supernatants did not appear to significantly affect the percentage of inoculated organisms undergoing cell division, as determined by a limiting dilution assay. Therefore, these results indicate that abscess fluid supernatants extend the lag phase of C. albicans growth, an effect similar to that seen with zinc-deprived organisms.