Comparison of BL-S786 with cephalothin, cefamandole and cefoxitin in vitro and in treatment of experimental infections in mice.

Abstract

The activity of BL-S786 [a new cephalosporin] was compared to that of cephalothin, cefamandole and cefoxitin in vitro and in treatment of experimental infections in mice. In broth dilution tests, the activity of BL-S786 was less than cephalothin or cefamandole against Staphylococcus aureus and less than cefamandole or cefoxitin against Haemophilus influenzae. BL-S786 and cefamandole were the 2 most active drugs against cephalothin-sensitive Enterobacteriaceae. In tests with cephalothin-resistant Enterobacteriaceae, BL-S786 was generally less active than cefamandole but more active than cefoxitin against all strains except Proteus and Providencia. Regardless of the comparative in vitro activity of the 4 drugs, BL-S786 was the most effective drug in treatment of mice lethally infected with Enterobacteriaceae. Protection from lethality was associated with clearance of bacteremia by each of the 4 drugs. In several tests where in vitro activity was not predictive of in vivo efficacy, selection of resistance in vivo occurred.