Comparative in-vitro activity of Sch 34343, imipenem, cefpirome and cefotaxime

The in-vitro activity of Sch 34343 was compared with that of imipenem, cefpirome and cefotaxime against clinical isolates of important bacterial pathogens. Sch 34343 was very stable to changes in media, human serum concentration, pH and inoculum size. Enterobacteriaceae, including strains resistant to aminopenicillins and established cephalosporins, were susceptible to Sch 34343. In the case of Acinetobacter spp., imipenem was the only highly active antibiotic. Pseudomonas aeruginosa (and most other Pseudomonas spp.) were insensitive to Sch 34343. Activity against Haemophilus influenzae was greater than that of imipenem but less than that of cefotaxime and cefpirome. Sch 34343 activity against Gram-negative anaerobic rods was greater than that of cefoxitin and comparable to imipenem. All methicillin-sensitive staphylococci were inhibited by 1 mg/l of Sch 34343, 0.5 mg/l of imipenem, 2 mg/l of cefpirome and 8 mg/l of cefotaxime. Activity of all four against methicillin-resistant staphylococci was low. Streptococcus faecalis was inhibited by 16 mg/l of Sch 34343 and 2 mg/l of imipenem. The activity of Sch 34343 was not affected by a beta-lactamase inactivating third generation cephalosporins.