Antibacterial effect of imipenem in vitro against important aerobic and anaerobic strains isolated from clinical specimens.

Imipenem is a thienamycin antibiotic of the first generation with broad antibacterial activity. It covers all gram-positive organisms (including Streptococcus faecalis) and gram-negative bacteria (including Pseudomonas aeruginosa and Serratia spp.) as well as Bacteroides fragilis and other Bacteroides species. In this comparative study the antimicrobic effect against 1020 gram-negative, 927 gram-positive and 352 anaerobic strains from fresh clinical isolates was tested and compared with that of other frequently used antibiotics. The minimum inhibitory concentrations (MIC) were determined by means of a serial dilution test with micro standard plates. Within the group of gram-negative strains, imipenem was the most active antibiotic with a MIC90 of less than or equal to 0.25 mg/l for most isolates. Imipenem shows a broad spectrum of activity against gram-negative pathogenic bacteria including Escherichia coli, Klebsiella spp., Proteus spp, Enterobacter spp., Citrobacter spp. and Serratia spp., and also covers resistant strains of Pseudomonas aeruginosa, Acinetobacter spp. and Alcaligenes faecalis. Imipenem also shows high inhibiting activity against gram-positive strains and anaerobic pathogens.