Efficacy of antibacterial drugs in mice with complex infection by Candida albicans and Escherichia coli.

We investigated the effect of seven antibacterial antibiotics: kanamycin, gentamicin, tetracycline, minocycline, ampicillin, piperacillin and cefotaxime, on survival of mice infected sequentially with a lethal dose of Candida albicans and a sublethal dose of Escherichia coli. The mortality of C. albicans-infected mice was facilitated by the superinfection with E. coli. When administered to mice with C. albicans/E. coli complex infection, aminoglycosides and tetracyclines significantly prolonged the survival period as compared with the infected and untreated controls. The recovery of viable counts of E. coli from the renal tissues was rapidly reduced by the treatment with gentamicin or minocycline, compared to the untreated control. Thus it was concluded that nullification by the treatment with aminoglycosides or tetracyclines of the enhancing effect of E. coli superinfection on the lethality of C. albicans-infected mice is due to early elimination of E. coli from the kidney.