In-vitro activity and -lactamase stability of Sch 29482, a penem antibiotic: Comparisons with ceftazidime and moxalactam

Open Access
Publisher Website
Google Scholar
Abstract
The in-vitro activity of the penem Sch 29482 (SCH), ceftazidime and moxalactam was studied against cephalothin-resistant strains of Enterobacteriaceae, Pseudomonas aeruginosa and Bacteroides fragilis . In all three antibiotics high in-vitro activity was combined with β -lactamase stability against Enterobacteriaceae. The MBC 50 was, respectively 2, 4 and 2 mg/l. SCH was not active against Ps. aeruginosa but was highly active against Bact. fragilis and, with few exceptions, was not inactivated by their β -lactamases. Ceftazidime showed high and moxalactam intermediate activity against Ps. aeruginosa strains. MIC determinations in broth were preferable to agar MICs for testing susceptibility to these new β -lactam antibiotics, but the MBC gave the truest reflection of their activity. The stability of new β -lactam antibiotics to β -lactamases must be tested by special methods, such as inactivation by bacterial enzyme preparations and time-killing assays with selected strains.