The clinical significance of clindamycin-resistant Bacteroides fragilis.

The Bacteroides fragilis group of bacteria are the most numerous microorganisms in the colon and the most common anaerobic isolates from human infections. Although clindamycin hydrochloride is still considered the antibiotic of choice for treatment of infections with these bacteria, resistant strains are becoming more common. To determine the clinical significance of clindamycin-resistant bacteroides, we reviewed the charts of 14 patients with resistant isolates. Clindamycin resistance was a major factor in the clinical course of at least four patients. Three of these did not recover until they were treated with effective antimicrobials. Seven patients had been treated with either erythromycin or clindamycin before isolation of the resistant strain. These observations underscore the importance of antimicrobial sensitivity testing of the B fragilis group and of considering the possibility of resistance when patients infected with Bacteroides fail to respond to clindamycin treatment.