COMPARATIVE IN-VITRO ACTIVITY OF MEROPENEM VERSUS OTHER EXTENDED-SPECTRUM ANTIMICROBIALS AGAINST RANDOMLY CHOSEN AND SELECTED RESISTANT CLINICAL ISOLATES TESTED IN 26 NORTH-AMERICAN CENTERS

The in vitro antibacterial activity of meropenem and up to nine other antimicrobials was compared in studies at 26 North American centers fr om 1989 to 1992 with use of standardized and controlled procedures for determining minimal inhibitory concentrations (MICs) against 12,483 r ecent clinical isolates and additional drug-resistant strains. Overall , carbapenems were the most active drugs. The antibacterial activity o f meropenem was consistent against random isolates in all centers; how ever, inclusion of large proportions of multidrug-resistant gram-negat ive aerobes by some centers did increase MICs of meropenem and the com parators. Meropenem was 4-64 times more active than imipenem against g ram-negatives, including Enterobacteriaceae organisms, Pseudomonas aer uginosa, Burkholderia cepacia, Neisseria meningiditis, and Haemophilus influenzae. Imipenem was up to 2-4 times more active than meropenem a gainst some gram-positive cocci, including Enterococcus faecalis. Carb apenems were similarly active against anaerobes, and resistant strains were rarely encountered. Meropenem, unlike imipenem or ceftazidime, w as bactericidal for all strains of Enterobacteriaceae, P. aeruginosa, and gram-positive cocci tested at less than or equal to 8 times the MI G. A lack of antibiotic cross-resistance was frequently observed betwe en comparator-resistant strains and meropenem. These data suggest the potential utility of meropenem as a monotherapeutic agent against a br oad range of pathogens.