In-vitro activity of meropenem against clinical isolates in a multicentre study in Italy

A multicentre in-vitro study was undertaken to evaluate the susceptibility of bacterial pathogens isolated in different Italian hospitals to meropenem. A total of 1399 aerobic and 452 anaerobic strains was analysed. Comparative agents were imipenem, cefotaxime, ceftazidime, ceftriaxone, piperacillin, ciprofloxacin, genta-micin, amikacin, plus vancomycin when appropriate. The MIC ranges (mg/l) of meropenem were: 0.015–2 for Klebsiella spp., Proteus spp., Morganella morganii and Providencia spp.; < 0.008–1 for Escherichia coli; 0.016–32 for Serratia spp.; 0.03–2 for Enterobacter spp. and Citrobacter spp.; 0.03– > 128 for Acinetobacter anitratus; 0.03–32 for Pseudomonas spp.; < 0.008–0.5 for Haemophilia spp. and Neisseria spp.; 0.015–64 for Staphylococcus spp.; 0.06– > 128 for Enterococcus spp.; < 0.008-0-25 for Streptococcus spp.; 0.016–8 for Fusobacterium spp.; 0.03–8 for Bacteroides spp.; < 0.06–0.5 for anaerobic Gram-positive cocci; 0.08–2 for Clostridium spp. Mero-penem exhibited superior antibacterial activity against the aerobic and anaerobic strains tested when compared to the other β-lactam drugs. The new carbapenem was as active as ciprofloxacin and more active than imipencm and the aminoglycosides against Enterobacteriaceae and Ps. aeruginosa. It was also more active than ciprof-loxacin against most strains of Gram-positive cocci. Meropenem was slightly less potent than imipenem against staphylococci and enterococci, with the exception of oxacillin-susceptible Staph. aureus against which meropenem and imipenem exhibited similar antibacterial activity.