title: Comparative in vitro activities of amoxicillin-clavulanate, ampicillin-sulbactam and piperacillin-tazobactam against strains of Escherichia coli and proteus mirabilis harbouring known beta-lactamases.
abstract: Strains of Escherichia coli (N = 124) and Proteus mirabilis (N = 29) harboring known beta-lactamases were analyzed as to their susceptibility to ampicillin, amoxicillin, and piperacillin alone and in combination with sulbactam, clavulanate, and tazobactam. With TEM 1-producing E. coli, a correlation between specific beta-lactamase activity and the MIC of piperacillin and ampicillin-sulbactam was observed. These strains also showed significant differences in susceptibilities to the various combinations, suggesting that, at least in strains resistant to one combination, several beta-lactam/beta-lactamase inhibitor combinations should be tested in the laboratory. All combinations tested enhanced the activity of the beta-lactam towards TEM 1-producing E. coli, piperacillin-tazobactam being the most active. The drugs were less active to OXA 1 enzymes; solely with piperacillin-tazobactam 90% of strains were within the therapeutic range of the drug. Sulbactam acted synergistically to chromosomally encoded beta-lactamases, whereas amoxicillin-clavulanate was inactive. Piperacillin and piperacillin-tazobactam inhibited all strains producing chromosomally encoded beta-lactamases at concentrations within the therapeutic range of the drugs. In contrast, TEM 2 of P. mirabilis was not sensitive to ampicillin-sulbactam, but to the other combinations; here again piperacillin-tazobactam was the most active.
authors.affiliation: Institut für Medizinische Mikrobiologie, Medizinische Universität, Lübeck, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Gatermann
authors.forename: R
authors.initials: R
authors.lastname: Marre
mesh_terms: D000658:Amoxicillin / Q000494:pharmacology*; D019980:Amoxicillin-Potassium Clavulanate Combination; D000667:Ampicillin / Q000494:pharmacology*; D002969:Clavulanic Acids / Q000494:pharmacology*; D004359:Drug Therapy, Combination / Q000494:pharmacology; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects* / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D010397:Penicillanic Acid / Q000494:pharmacology*; D010878:Piperacillin / Q000494:pharmacology*; D011513:Proteus mirabilis / Q000187:drug effects* / Q000201:enzymology; D013045:Species Specificity; D013407:Sulbactam / Q000494:pharmacology*; D000078142:Tazobactam; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000096:biosynthesis
chemical_list: D002969:Clavulanic Acids; D065093:beta-Lactamase Inhibitors; C035444:sultamicillin; D019980:Amoxicillin-Potassium Clavulanate Combination; D000667:Ampicillin; D000658:Amoxicillin; D010397:Penicillanic Acid; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1; C056342:beta-lactamase TEM-2; D013407:Sulbactam; D000078142:Tazobactam; D010878:Piperacillin