Antibiotic susceptibility of blood culture isolates of anaerobic bacteria at a Norwegian university hospital

In the present study the susceptibility of 200 blood culture isolates of anaerobic bacteria to benzylpenicillin, clindamycin, metronidazole, imipenem and piperacillin-tazobactam was examined. Metronidazole, imipenem, and piperacillin-tazobactam showed the highest activity, with 98.5% of the isolates being fully susceptible to either agent. A high rate of reduced susceptibility to clindamycin among both Bacteroides spp. (37%) and Clostridium spp. (28%) was found. Almost all Bacteroides isolates were resistant to penicillin, and only 60% of Prevotella spp. were susceptible to this agent. The antibiotic susceptibility of anaerobic bacteria in Norway should be surveyed regularly.