title: Prevalence, mechanisms, and risk factors of carbapenem resistance in bloodstream isolates of Pseudomonas aeruginosa.
abstract: We examined the prevalence of various carbapenem resistance mechanisms in Pseudomonas aeruginosa bloodstream isolates from a university-affiliated hospital. Isolates obtained in 2003 and 2004 were screened for meropenem/imipenem resistance, and clonality was assessed by repetitive-element-based polymerase chain reaction. The presence of carbapenemase and AmpC overexpression was ascertained by spectrophotometric assays. Outer membrane protein profiles were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and efflux pump overexpression was confirmed by Western blotting. We examined 129 nonrepeat isolates; 21 isolates (from 13 distinct clones) were resistant to meropenem or imipenem (prevalence rate = 16.3%). Nineteen (90.5%) carbapenem-resistant isolates had reduced OprD expression, and 6 (28.6%) isolates had overexpression of MexB. Increased length of hospital stay was identified as a significant risk factor for bacteremia due to carbapenem-resistant P. aeruginosa. Understanding the prevalence and mechanism of carbapenem resistance in P. aeruginosa may guide empiric therapy for nosocomial infections in our hospital.
authors.affiliation: Department of Clinical Sciences and Administration, University of Houston College of Pharmacy, Houston, TX 77030, USA. vtam@uh.edu
authors.forename: Vincent H
authors.initials: VH
authors.lastname: Tam
authors.forename: Kai-Tai
authors.initials: KT
authors.lastname: Chang
authors.forename: Mark T
authors.initials: MT
authors.lastname: LaRocco
authors.forename: Amy N
authors.initials: AN
authors.lastname: Schilling
authors.forename: Shana K
authors.initials: SK
authors.lastname: McCauley
authors.forename: Keith
authors.initials: K
authors.lastname: Poole
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Garey
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology*; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis; D015153:Blotting, Western; D015780:Carbapenems / Q000494:pharmacology*; D002352:Carrier Proteins / Q000032:analysis; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D024881:Drug Resistance, Bacterial; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006785:Hospitals, University; D006801:Humans; D007902:Length of Stay; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D015995:Prevalence; D011552:Pseudomonas Infections / Q000453:epidemiology / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D012307:Risk Factors; D001618:beta-Lactamases / Q000032:analysis
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D015780:Carbapenems; D002352:Carrier Proteins; D001618:beta-Lactamases