The in-vitro activity of three long-acting cephalosporins against Bacteroides fragilis, Peptostreptococcus species and Clostridium perfringens.

The in-vitro activity of three long-acting cephalosporins (cefotetan, cefonicid and ceftriaxone) was compared against 206 clinical isolates of Bacteroides fragilis, Peptostreptococcus species and Clostridium perfringens, using an agar dilution procedure to determine minimum inhibitory concentrations (MICs). Clindamycin was included as a comparator. Cefotetan was much more active than the two other cephalosporins against strains of Bacteroides fragilis (MIC90 16 mg/l compared with greater than 128 mg/l for the other two agents). Cefotetan also demonstrated superior activity against anaerobic cocci. All three compounds showed good activity against strains of Clostridium perfringens. Clindamycin was active against all of the test strains.