In-vitro study of the susceptibility of cefoxitin/cefotetan resistant Bacteroides fragilis group strains to various other antimicrobial agents

The in-vitro activity of various /Mactam antibiotics, /Mactam//Mactamase inhibitor combinations, clindamycin, and mctronidazole was determined against Bacteroides fragilis group isolates that were resistant to both cefoxitin and cefotetan. Among the cephalosporins tested ceflizoxime was the most active with 80 % of the strains susceptible, followed by cefotaxime (65 % susceptible), and cefoperazone (47% susceptible). Pipcracillin and clindamycin showed comparable activity to ceftizoxime with 80 % and 81 % susceptible, respectively. The'addition of a /Mactamase inhibitor (sulbactam, clavulanate, or tazobactam) enhanced the activity of the various /?-lactam agents from 4-fold to 16-fold overall. One strain of B. fragilis was found that was resistant to all /Mactam agents either alone or in combination. All strains in this study were susceptible to S 4 mg/1 of mctronidazole