Effects of erythromycin, clarithromycin, roxithromycin and azithromycin on murine gut colonization by Candida albicans.

Male Crl:CD1(ICR) BR mice were fed either chow containing Candida albicans or regular chow. The gastrointestinal tract of the C. albicans-fed mice was permanently colonized by the yeast. Groups of C. albicans-colonized mice were subsequently treated either with a macrolide (erythromycin, clarithromycin, roxithromycin or azithromycin) for 10 days or a normal saline solution (controls). Other controls included non-colonized mice receiving the same antibiotics or a saline solution. Our data are as follows: (i) C. albicans-colonized mice treated with each macrolide had highly significant increase in colony counts of C. albicans in their stools compared to C. albicans-colonized mice treated with saline only; (ii) discontinuation of macrolide treatment showed a trend towards lower colony counts, which was not statistically significant (colony counts were sustained even after discontinuation of antibiotic treatment); (iii) dissemination of C. albicans did not occur; (iv) mice fed regular chow treated with the study drugs or saline did not have any yeasts in their stools. In conclusion, oral erythromycin, clarithromycin, roxithromycin and azithromycin cause a modest increase of the C. albicans concentration of the gastrointestinal tract. This increase is not associated with a higher risk of disseminated candidiasis.