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 co mpared with those of six other oral antimicrobial agents against 598 b acterial isolates representing 51 different species. WY-49605 exhibite d good activity against most gram-positive bacteria and members of the family Enterobacteriaceae. It had little activity against nonfermenti ng gram-negative bacilli, Enterobacter spp., Serratia spp., enterococc i, Staphylococcus haemolyticus, and methicillin-resistant Staphylococc us aureus. Its activity was unaffected by the beta-lactamases of Neiss eria gonorrhoeae, Haemophilus influenzae, and staphylococci, Disk diff usion susceptibility tests were performed with 5-, 10-, 15-, and 30-mu g WY-49605 disks, The 5-mu g disk is recommended, with tentative brea kpoints of greater than or equal to 16 mm for susceptibility (MIG, les s than or equal to 2.0 mu g/ml) and less than or equal to 12 mm for re sistance (MIG, greater than or equal to 8.0 mu g/ml).