title: In vitro stepwise selection of resistance to quinolones, beta-lactams and amikacin in nosocomial gram-negative bacilli.
abstract: The ability of six antibiotics to produce resistance by stepwise selection on agar medium was assessed in 24 gram-negative rods. Escherichia coli was the strain least prone to selection of resistance, whereas Pseudomonas aeruginosa frequently developed resistance to all antibiotics. When used alone, ciprofloxacin, pefloxacin, amikacin, ceftazidime and cefpirome were associated with a comparable risk of acquired resistance (in 14 to 17 out of 24 strains); imipenem selected resistant strains in 10/24 isolates (5/18 in non-pseudomonas strains). The number of strains exhibiting cross resistance with structurally unrelated antibiotics was 11 after pefloxacin treatment, eight after exposure to ciprofloxacin, six after ceftazidime, and one after imipenem or cefpirome. The combination of ciprofloxacin with amikacin was less efficient in reducing acquisition of resistance than the combination of ciprofloxacin with a beta-lactam: ciprofloxacin plus cefpirome was especially potent in this respect.
authors.affiliation: Dept. of Genetics and Microbiology, Centre Médical Universitaire, University of Geneva, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Michéa-Hamzehpour
authors.forename: A
authors.initials: A
authors.lastname: Kahr
authors.forename: J C
authors.initials: JC
authors.lastname: Pechère
mesh_terms: D000583:Amikacin / Q000627:therapeutic use*; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D000890:Anti-Infective Agents / Q000627:therapeutic use*; D003428:Cross Infection / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology*; D004352:Drug Resistance, Microbial; D004359:Drug Therapy, Combination / Q000627:therapeutic use*; D005069:Evaluation Studies as Topic; D024841:Fluoroquinolones; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D017053:Infection Control; D012307:Risk Factors; D047090:beta-Lactams
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D047090:beta-Lactams; D000583:Amikacin