In-vitro evaluation of Sch 34343: antimicrobial activity, beta-lactamase stability and inhibition

Sch 34343 was compared with representative parenteral beta-lactams including monobactams (aztreonam), 1-oxa-beta-lactams (latamoxef), carbapenems (imipenem) and cephalosporins (cefamandole, cefoperazone, cefotaxime, cefsulodin and ceftazidime). Sch 34343 was active against the Enterobacteriaceae (MIC50 range, 0.12-4.0 mg/l) and the facultative Gram-positive cocci (MIC50 range, 0.03-4.0 mg/l), and was comparable to the third-generation cephalosporins and imipenem. Pseudomonas aeruginosa and other Pseudomonas spp. were not susceptible to Sch 34343. Haemophilus influenzae and Neisseria spp. were all susceptible to less than or equal to 2.0 mg/l of Sch 34343. Methicillin-resistant staphylococci (MIC90, 32 mg/l) appear to be insusceptible to Sch 34343. Sch 34343 inhibited the majority of cefotaxime- and gentamicin-resistant bacteria (MICs less than or equal to 8.0 mg/l). The new penem was stable to hydrolysis by 11 beta-lactamase preparations (both plasmid- and chromosomally-mediated types). Sch 34343 inhibited beta-lactamases as did other newer cephalosporins.