CH-1240

The antibacterial activity of novel beta-lactamase inhibitors, 6-exomethylene penamsulfones (CH1240, CH2140), has been compared in vivo with that of sulbactam and clavulanic acid against beta-lactamase producing strains. In vivo microbiological assessment was used as experimental mouse infection model by gram negative strains. Against Pseudomonas aeruginosa F0013, cefoperazone/CH1240 was slightly less active than sulbactam. Ampicillin/CH1240 was more active than sulbactam against Citrobacter diversus species. That of ampicillin/CH2140 was less effective than sulbactam against Escheriachia coli 3457. Especially against Citrobacter diversus 2046E, amoxicillin/CH2140 was the most potent and amoxicillin/CH1240 was slightly more active than clavulanic acid. Consequently the difference in efficacy between the drug combinations appears to be related to the degree of protection afforded the animals by the beta-lactamase inhibitors. CH1240 and CH2140 are promising new agents and should undergo further investigations.