title: Nosocomial acquisition of Pseudomonas aeruginosa resistant to both ciprofloxacin and imipenem: a risk factor and laboratory analysis.
abstract: In vitro, ciprofloxacin can select for dual resistance to fluoroquinolones and imipenem in Pseudomonas aeruginosa via a mutation in the regulatory gene, mexT, which downregulates OprD and upregulates MexEF-OprN. We performed a nested case-control study of patients in two medical intensive care units participating in an observational cohort study. Patients colonized or infected with P. aeruginosa resistant to both ciprofloxacin and imipenem (cases) were compared to controls. The presence of OprD and OprN from cases was evaluated by Western blot. In total, 44 cases were compared to 132 controls. Imipenem exposure [adjusted odds ratio (AOR) = 11.4, p = 0.044] was significantly associated with case status, but fluoroquinolone use was not (AOR = 1.0, p = 0.998). Neither OprD nor OprN were detected in any isolate. Fluoroquinolone use was not a risk factor for acquisitions of dually resistant P. aeruginosa. The absence of OprN in these isolates suggests that dual resistance is not due to mexT mutations.
authors.affiliation: Rollins School of Public Health, Emory University, Atlanta, GA, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Mueller
authors.forename: M K
authors.initials: MK
authors.lastname: Hayden
authors.forename: S K
authors.initials: SK
authors.lastname: Fridkin
authors.forename: D K
authors.initials: DK
authors.lastname: Warren
authors.forename: L
authors.initials: L
authors.lastname: Phillips
authors.forename: K
authors.initials: K
authors.lastname: Lolans
authors.forename: J P
authors.initials: JP
authors.lastname: Quinn
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis; D015153:Blotting, Western; D016022:Case-Control Studies; D002939:Ciprofloxacin / Q000494:pharmacology* / Q000627:therapeutic use; D003428:Cross Infection / Q000382:microbiology / Q000635:transmission*; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D015378:Imipenem / Q000494:pharmacology* / Q000627:therapeutic use; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D018272:Porins / Q000096:biosynthesis; D011552:Pseudomonas Infections / Q000382:microbiology / Q000635:transmission*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; C105708:OprN protein, Pseudomonas aeruginosa; D018272:Porins; C077157:OprD protein, Pseudomonas aeruginosa; D002939:Ciprofloxacin; D015378:Imipenem