Synergistic effects of Candida and Escherichia coli on gut barrier function

Background: Disruption of the indigenous gut microflora with overgrowth of gram-negative bacteria and Candida species is common in the critically ill patient, These organisms readily translocate in vitro, which may cause sept ic complications and organ failure. A synergistic effect between Escherichi a coli and C. albicans in polymicrobial infections has been demonstrated, A n interaction between these organisms at the mucosal barrier is unknown. Methods: Caco(2) monolayers were grown to confluence in a two compartment c ulture system. E. coli and C. albicans or E, coil alone were added to the a pical chambers. Secretory immunoglobulin A was added to half of the apical chambers as well. Cell cultures were incubated for a total of 240 minutes. Basal media were sampled at timed intervals for quantitative culture. Monol ayer integrity was confirmed by serial measurement of transepithelial elect rical resistance. Results: Secretory immunoglobulin A decreased bacterial translocation acros s Caco(2) monolayers challenged with E. coli alone. Transepithelial passage of E, coli was significantly increased by coculture of bacteria with C. al bicans. Augmentation of bacterial translocation by Candida occurred even in the presence of secretory immunoglobulin A, Conclusions: Candida colonization of the GI tract may impair mucosal barrie r defense against gram-negative bacteria. The clinical role of gut antifung al prophylaxis in protecting against gut derived gram-negative sepsis is sp eculative.