In vitro activity of SCH-34343, a new penam, and other antimicrobial agents against clinical isolates from cancer patients.

The in vitro activity of SCH-34343, a new penam antibiotic, was tested against gram-positive and gram-negative isolates from cancer patients, and compared to that of 7 other antimicrobial agents. SCH-34343 was extremely active against the Enterobacteriaceae with MIC90 ranging from 0.39 to 6.25 micrograms/ml for Citrobacter spp., Enterobacter spp., Escherichia coli, Klebsiella spp., Proteus spp. and Serratia marcescens. It was less active against Acinetobacter spp. (MIC90 6.25-12.5 micrograms/ml) and had poor activity against Pseudomonas aeruginosa. Among gram-positive isolates group A and G beta-hemolytic Streptococci were extremely susceptible to SCH-34343 (MIC90 0.025-0.05 micrograms/ml). Good activity against methicillin-susceptible coagulase-positive and coagulase-negative Staphylococci and Listeria monocytogenes, and moderate activity against Enterococci was also seen.