Comparative in vitro antimicrobial activity of carumonam (Ro 17-2301) and its influence on the activity of other antibiotics.

The antimicrobial activity of carumonam (Ro 17-2301) was compared with that of 20 antibiotics against 338 clinical isolates. Carumonam did not possess activity against gram-positive cocci, MIC90 of carumonam were less than or equal to 0.5 mg/l for Enterobacteriaceae, except for Citrobacter (less than or equal to 8 mg/l) and less than or equal to 32 mg/l for nonfermenters. It was slightly more active than aztreonam against gentamicin-resistant bacilli (MIC90 less than or equal to 64 vs greater than or equal to 256). Combinations of carumonam with antibiotics with activity against gram-positive microorganisms were indifferent.