Comparative in-vitro activity of meropenem against selected pathogens from hospitalized patients in The Netherlands. MASTIN Study Group.

Thirty laboratories evaluated the in-vitro activity of meropenem and 15 commonly used antibiotics against selected microorganisms isolated in 1994-95 from hospitalized patients with serious infections requiring antibacterial treatment. Isolates (2169) from blood, sputum, pus or CSF were included. MICs were determined with Etest and NCCLS breakpoints were used. In general, the MICs of meropenem for Gram-positive isolates were found to be one- to six-fold higher than those of imipenem, except for Enterococcus faecalis. The MIC90 of meropenem for E. faecalis was high (32 mg/L) and distinctly higher than the MIC90 of imipenem (2 mg/L). The MICs of meropenem for Gram-negative isolates were two- to 24-fold lower, with the exception of Acinetobacter spp. Gram-negative fermentative strains, Enterobacter spp. in particular, isolated from patients in intensive care units (ICU) were more resistant to the -lactam antibiotics than those isolated from patients in non-intensive care wards. However, all Enterobacteriaceae, with and without inducible -lactamases, isolated from ICU patients were susceptible to meropenem.