In vitro activity of mecillinam and amoxicillin/clavulanic acid against strains of Escherichia coli producing TEM-1, Oxa-1 and chromosomal beta-lactamases.
The in vitro activity of mecillinam and amoxicillin/clavulanic acid against Escherichia coli strains producing beta-lactamases of the TEM-1, Oxa-1 and chromosomal type were studied using the broth and agar dilution technique. In addition the beta-lactamase activity was determined. The experiments indicated that the beta-lactamase types differed in their influence on the minimum inhibitory concentrations. Both, mecillinam and amoxicillin/clavulanic acid were considerably more active against TEM-1 strains than ampicillin alone, but, with increasing specific beta-lactamase activity, a decrease of susceptibility was found. Strains producing Oxa-1 and chromosomal beta-lactamases usually where highly susceptible to mecillinam but only moderately sensitive or resistant to the combination of amoxicillin/clavulanic acid. In vitro activity of TEM-1 E. coli to mecillinam was strongly reduced when tested in a broth dilution technique. These test systems, however, did not affect the susceptibility of Oxa-1 and chromosomal beta-lactamase producing E. coli strains to either antibiotic.
Marre
R
R
Institut für Medizinische Mikrobiologie, Medizinischen Universität zu Lübeck, Fed. Rep. of Germany.
Schulz
E
E
D000560:Amdinocillin / Q000494:pharmacology*; D000658:Amoxicillin / Q000494:pharmacology*; D002876:Chromosomes, Bacterial / Q000201:enzymology; D019818:Clavulanic Acid; D002969:Clavulanic Acids / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000378:metabolism*
D002969:Clavulanic Acids; D019818:Clavulanic Acid; D000658:Amoxicillin; D001618:beta-Lactamases; D000560:Amdinocillin