Bacteriostatic and bactericidal in-vitro activity of meropenem against clinical isolates, including Mycobacterium avium complex.

For clinical isolates the MICs of meropenem were significantly lower than the MICs of imipenem, especially against Pseudomonas aeruginosa. Furthermore, meropenem was bactericidal for Pseudomonas spp., including Ps. (Xanthomonas) maltophilia, and staphylococci, with MBCs on average only two-fold above the respective MICs. The bactericidal activity was confirmed by killing curve assays. Strains with high meropenem MICs (greater than or equal to 8 mg/l) were killed by a combination of the carbapenem and amikacin, with kinetics that indicated synergism between the two antimicrobial agents.