In-vitro activity of ceftizoxime against anaerobic bacteria and comparison with other cephalosporins

The in-vitro activity of ceftizoxime against anaerobic bacteria, especially Bacteroides fragilis , is reviewed, based on our own experience as well as on other sources. In-vitro data on ceftizoxime and other cephalosporins and related β-lactam antibiotics against more than 500 clinical isolates of anaerobic bacteria (as determined by the NCCLS reference method) were compared at Vancouver General Hospital. Ceftizoxime exhibited excellent in-vitro activity against all anaerobes, including Bact. fragilis , when tested by the NCCLS reference method, and was comparable in activity to cefoxitin and cefotaxime. However, marked variation in susceptibility results was noted against Bact. fragilis and the Bact. fragilis group, primarily related to the size of inoculum and type of media utilized in the different studies. With the supplemented brucella agar technique, ceftizoxime was distinctly less active against the Bact. fragilis group. These data underscore the importance of standardized techniques for in-vitro susceptibility testing of anaerobes. Further in-vitro and clinical studies are clearly indicated.