title: The in-vitro activity of piperacillin/tazobactam, ciprofloxacin, ceftazidime and imipenem against multiple resistant gram-negative bacteria.
abstract: One hundred and fifty Gram-negative bacterial strains including respiratory pathogens, such as Haemophilus influenzae and Branhamella catarrhalis, and Enterobacteriaceae with known resistance to beta-lactam and other antibiotics were tested in vitro for sensitivity to piperacillin, piperacillin/tazobactam (ratio 8:1), ceftazidime, ciprofloxacin and imipenem. A 16-fold or greater reduction in the MIC90 of piperacillin was achieved by the addition of tazobactam, in the respiratory pathogens, thus bringing them within the susceptible range. Among the Enterobacteriaceae, a 32-fold or greater reduction in the MIC90 was found for Providencia stuartii, Proteus mirabilis and Aeromonas hydrophila. When compared with the other three antimicrobials, the combination was found to be active against fewer species of multiply resistant Enterobacteriaceae, but equally effective against H. influenzae and B. catarrhalis.
authors.affiliation: Department of Microbiology, North Middlesex Hospital, Edmonton, London, UK.
authors.forename: S
authors.initials: S
authors.lastname: Mehtar
authors.forename: Y J
authors.initials: YJ
authors.lastname: Drabu
authors.forename: P H
authors.initials: PH
authors.lastname: Blakemore
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002442:Ceftazidime / Q000494:pharmacology; D002939:Ciprofloxacin / Q000494:pharmacology; D002954:Citrobacter / Q000187:drug effects; D004352:Drug Resistance, Microbial; D004755:Enterobacteriaceae / Q000187:drug effects; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D015378:Imipenem / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D010397:Penicillanic Acid / Q000494:pharmacology; D010878:Piperacillin / Q000494:pharmacology; D012705:Serratia / Q000187:drug effects; D000078142:Tazobactam
chemical_list: D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin; D015378:Imipenem; D010397:Penicillanic Acid; D002442:Ceftazidime; D000078142:Tazobactam; D010878:Piperacillin