Effect of imipenem-cilastatin therapy on fecal flora.

Alteration of fecal flora was prospectively studied in 21 children receiving imipenem-cilastatin therapy under protocol for therapy of infections. Although no profound reduction in facultative or anaerobic flora was observed, qualitative and quantitative increases in organisms which were resistant or less susceptible to imipenem occurred. Of 21 patients, 13 (62%) had increases in counts of Enterococcus spp. of at least 10(3) organisms per g (wet weight) of stool, and 7 (33%) had acquisition of or similar increases in counts of Candida species. No change in susceptibility of isolates to imipenem was demonstrable during therapy. However, the MICs for 50 and 90% of the strains of Enterococcus spp. (2 and 8 micrograms/ml, respectively) were higher than those previously reported.