title: Activity of imipenem, third-generation cephalosporins, aztreonam and ciprofloxacin against multi-resistant gram-negative bacilli isolated from Chilean hospitals.
abstract: The activity of imipenem against nosocomial strains of Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter spp. and methicillin-resistant Staphylococcus aureus resistant to some third-generation cephalosporins, aztreonam, or ciprofloxacin was assessed. These strains represent the most prevalent multi-resistant nosocomial microorganisms in Chile since they were isolated from clinical specimens in 11 Chilean hospitals. A high proportion of the strains were resistant to several beta-lactams, yet all strains of K. pneumoniae and Acinetobacter spp. were susceptible to imipenem; resistance was exhibited by only one strain of P. aeruginosa and 16 strains of S. aureus. Synergy between cefotaxime and clavulanic acid was found in almost all strains of K. pneumoniae, suggesting the presence of plasmid-coded beta-lactamases, probably with extended-spectrum activity. Killing A. baumannii by imipenem was rapid, but slower for P. aeruginosa. Killing of K. pneumoniae was also somewhat slower despite the lower MIC of imipenem for this strain. Bactericidal activity was even slower against one strain of methicillin-resistant S. aureus. These results suggest that imipenem would be an adequate alternative to other broad-spectrum agents in the treatment of infections due to nosocomial multi-resistant Gram-negative bacilli.
authors.affiliation: Departamento de Microbiologia, Facultad de Ciencias Biologicas, Universidad de Concepcion, Chile.
authors.forename: R
authors.initials: R
authors.lastname: Zemelman
authors.forename: H
authors.initials: H
authors.lastname: Bello
authors.forename: M
authors.initials: M
authors.lastname: Dominguez
authors.forename: G
authors.initials: G
authors.lastname: Gonzalez
authors.forename: S
authors.initials: S
authors.lastname: Mella
authors.forename: A
authors.initials: A
authors.lastname: Garcia
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001398:Aztreonam / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology; D002677:Chile; D002939:Ciprofloxacin / Q000494:pharmacology; D003428:Cross Infection / Q000382:microbiology; D004352:Drug Resistance, Microbial; D004357:Drug Synergism; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D007202:Indicators and Reagents; D008826:Microbial Sensitivity Tests
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D007202:Indicators and Reagents; D002939:Ciprofloxacin; D015378:Imipenem; D001398:Aztreonam