Antimicrobial resistance in oral and colonic bacteroides

Antimicrobial resistance in Bacteroides from oral and colonic flora influences the selection of antimicrobial therapy to treat infections involving these organisms. An antimicrobial susceptibility study of 49 clinical isolates of oral bacteroides to 9 drugs revealed high resistance rates for penicillin 53%, for cefaclor 45%, and for tetracycline 27%, while there were low rates (less than 10%) with cefoxitin, piperacillin, clindamycin, chloramphenicol and metronidazole. Review of our U.S. nationwide survey of the susceptibility of colonic bacteroides (Bacteroides fragilis group) reveals low resistance to clindamycin, cefoxitin, piperacillin, imipenem, chloramphenicol and metronidazole. However, the identification of clindamycin, clindamycin, cefoxitin, piperacillin, imipenem and chloramphenicol resistant isolates is worrisome. The mechanism of resistance and the resistant transfer mechanism to the different classes of drugs in the oral and colonic bacteroides are reviewed.