Comparative in vitro antimicrobial activity of a new carbapenem, E1010, and tentative disc diffusion test interpretative criteria.

The susceptibility of 705 bacterial isolates representing 46 different species to E1010 (ER-35786), imipenem, meropenem and cefepime was determined by the NCCLS broth microdilution test. The MIC(90)s for E1010 were < or =1.0 mg/L for Enterobacteriaceae, fastidious Gram-negative bacteria, streptococci and anaerobes. E1010 was two- to four-fold more active than imipenem and meropenem against Pseudomonas aeruginosa, and four-fold more active than the other carbapenems against methicillin-resistant Staphylococcus aureus. Vancomycin-resistant enterococci and most Enterococcus faecium were resistant to all four drugs tested. The NCCLS disc diffusion test was performed simultaneously on the non-fastidious organisms. Assuming the MIC breakpoints for E1010 will be the same as for the other carbapenems, the disc diffusion zone diameter breakpoints of imipenem and meropenem would also be applicable to E1010.