COMPARISON OF IN-VITRO SUSCEPTIBILITIES OF BACTEROIDES AND FUSOBACTERIUM SPECIES IN INLAND SOUTHERN CALIFORNIA TO PUBLISHED PATTERNS AS A GUIDE TO EMPIRIC THERAPY

Anaerobic bacteria, particularly the Bacteroides group, are becoming i ncreasingly resistant to antimicrobials. Anaerobic susceptibility test ing is often not done routinely in clinical laboratories, causing clin icians to depend on national survey results or susceptibility patterns published by different centers. In this study, we have determined ana erobic susceptibility patterns of 200 clinical isolates of anaerobic g ram-negative bacilli from four hospitals in the inland counties of sou thern California (Inland Empire). Of 11 antibiotics tested, metronidaz ole and chloramphenicol were the most active, with no resistance noted , followed by imipenem, ticarcillin/clavulanate, and ampicillin/sulbac tam. Among cephalosporins, cefoxitin was the most active and cefotetan the least. Significant differences in the susceptibility pattern to c efoxitin were observed in one hospital. Differences between our inland patterns and those for Los Angeles Wadsworth VA Hospital were seen fo r cefoxitin in the B fragilis group and piperacillin for B fragilis. W e confirmed the National Committee for Clinical Laboratory Standards ( NCCLS) recommendation for periodic determination of anaerobic suscepti bility patterns. We also suggest that clinical laboratories routinely identify anaerobes to the species level to facilitate clinical applica tion of in vitro results.