Journal of Antimicrobial Chemotherapy (1992) 30, 811-820
© 1992 The British Society for Antimicrobial Chemotherapy
research-article |
Antimicrobial susceptibility of anaerobic bacteria in Australia
Department of Clinical Microbiology, Centre for Infectious Diseases and Microbiology, Westmead Hospital Westmead NSW 2145, Australia
Received 18 February 1992; accepted 14 July 1992
Correspondence to: Professor G. L. Gilbert
The susceptibilities of 900 clinical isolates of anaerobic bacteria to 14 antimicrobial agents were determined by an agar dilution technique. Chloramphenicol, imipenem and metronidazole were found to be active against virtually all of the strains; only a single Bacreroides fragilis isolate was resistant to both imipenem and metronidazole. The addition of clavulanic acid to amoxycillin and ticarcillin potentiated the activities of these agents against all anaerobes including members of the B.fragilis group. Ampicillin/sulbactam and clindamycin were the next most active agents. 91 and 89% of isolates respectively being susceptible.
Seventy-three per cent of the bacteria tested were susceptible to cefoxitin and 65% to cefotetan, with the MICs of almost 50% of the isolates clustering between 16 and 32 mg/L. There was also clustering around the breakpoint (64 mg/L) of piperacillin. Azithromycin exhibited poor activity against the B. fragilis group; only 18% of isolates were susceptible to 
4 mg/L. However, 92% of non-B. fragilis Bacteroidess group strains were susceptible to this agent. We conclude that imipenem, metronidazole, chloramphenicol, ticarcillin/clavulanate, co-amoxiclav and, to a lesser extent, ampicillin/sulbactam are suitable as empirical therapy for infections caused by anaerobic bacteria.