title: Complementary activity of mezlocillin and the combination of amoxicillin with clavulanic acid on Enterobacteriaceae.
abstract: The MICs of amoxicillin, mezlocillin and BRL 25,000, a combination of two parts amoxicillin and one part clavulanic acid (2AM + 1CA), were measured for 331 Enterobacteriaceae strains which produced beta-lactamases as demonstrated by nitrocefin. The MIC values for mezlocillin and the combination 2AM + 1CA were very similar for the total number of the strains investigated. When investigated separately according to the bacterial species, three different sensitivity groups were established for the above-mentioned preparations: 1) species with the same or similar sensitivity to mezlocillin and 2AM + 1CA (Escherichia coli and Shigella spp., amoxicillin-resistant strains); 2) species which were more sensitive to mezlocillin than to the combination 2AM + 1CA (Citrobacter spp., Enterobacter cloacae, Serratia spp. and indole-positive Proteus as well as strains of E. coli and Shigella spp. which produce a cephalosporinase and are sensitive to amoxicillin); 3) species which are more sensitive to 2AM + 1CA than to mezlocillin (amoxicillin-resistant Salmonella spp., Proteus mirabilis and Klebsiella pneumoniae). This complementary activity of mezlocillin and 2AM + 1CA against Enterobacteriaceae depended on the beta-lactamases produced.
mesh_terms: D000658:Amoxicillin / Q000494:pharmacology*; D019980:Amoxicillin-Potassium Clavulanate Combination; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004338:Drug Combinations / Q000494:pharmacology; D004755:Enterobacteriaceae / Q000187:drug effects*; D008802:Mezlocillin; D008826:Microbial Sensitivity Tests; D010406:Penicillins / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D010406:Penicillins; D019980:Amoxicillin-Potassium Clavulanate Combination; D000658:Amoxicillin; D008802:Mezlocillin