CANDIDA-ALBICANS AND ESCHERICHIA-COLI ARE SYNERGISTIC PATHOGENS DURING EXPERIMENTAL MICROBIAL PERITONITIS

Candida albicans has been isolated with increasing frequency during in traabdominal infection; yet its role as a pathogen or copathogen remai ns controversial. A recent experimental study of its effect during pol ymicrobial peritonitis indicated that it did not enhance mortality whe n added to an Escherichia coli challenge, but that study used fecal or mucin-based adjuvants which are known to markedly potentiate the leth ality of intraperitoneal bacteria. Therefore, we sought to examine the hypothesis that C. albicans and E. coli are synergistic copathogens t hat act in concert to increase mortality rates in experimental models of polymicrobial peritonitis, irrespective of the presence of growth a djuvant. To test this hypothesis, we assessed the mortality rates of p reviously healthy Swiss-Webster mice (20 g) that were challenged intra peritoneally tip) with E. coli, C. albicans, or both, in either the pr esence or the absence of hemoglobin-mucin. In the absence of hemoglobi n-mucin, E. coli plus C. albicans resulted in 83.3.% mortality (P < 0. 02) compared to either E. coli (0%) or C. albicans (0%) alone, In the presence of hemoglobin-mucin, the synergistic effect was not observed, lower numbers of E. coli alone (62.5%), C. albicans alone (75%), or b oth organisms together (100%, P > 0.05) provoked high lethality. These data demonstrate that in the absence of adjuvant, E. coli plus C. alb icans provoked synergistic lethality. However, in the presence of hemo globin-mucin the synergistic effect was no longer observed. Therefore, this study provides support for the contention that C. albicans is ca pable of acting as a copathogen during experimental peritonitis, but t hat this effect may be obscured by the presence of an adjuvant substan ce that itself markedly potentiates microbial growth. (C) 1997 Academi c Press.