ANTIBACTERIAL ACTIVITY OF WY-49605 COMPARED WITH THOSE OF 6 OTHER ORAL-AGENTS AND SELECTION OF DISK CONTENT FOR DISK DIFFUSION SUSCEPTIBILITY TESTING

The in vitro antimicrobial activity of an oral penem, WY-49605, was compared with those of six other oral antimicrobial agents against 598 bacterial isolates representing 51 different species. WY-49605 exhibited good activity against most gram-positive bacteria and members of the family Enterobacteriaceae. It had little activity against nonfermenting gram-negative bacilli, Enterobacter spp., Serratia spp., enterococci, Staphylococcus haemolyticus, and methicillin-resistant Staphylococcus aureus. Its activity was unaffected by the beta-lactamases of Neisseria gonorrhoeae, Haemophilus influenzae, and staphylococci, Disk diffusion susceptibility tests were performed with 5-, 10-, 15-, and 30-mu g WY-49605 disks, The 5-mu g disk is recommended, with tentative breakpoints of greater than or equal to 16 mm for susceptibility (MIG, less than or equal to 2.0 mu g/ml) and less than or equal to 12 mm for resistance (MIG, greater than or equal to 8.0 mu g/ml).