title: Carbapenem-resistant Acinetobacter baumannii: diversity of resistant mechanisms and risk factors for infection.
abstract: Carbapenem-resistant Acinetobacter baumannii (CRAB) are an increasing infectious threat in hospitals. We investigated the clinical epidemiology of CRAB infections vs. colonization in patients, and examined the mechanisms of resistance associated with elevated minimum inhibitory concentrations (MICs) for carbapenems. From January to June 2009, 75 CRAB strains were collected. CRAB infection was significantly associated with malignancy and a high APACHE II score. The most dominant resistance mechanism was ISAba1 preceding OXA-51, producing strains with overexpression of efflux pump. Strains carrying blaOXA-23-like enzymes had higher carbapenem MICs than those carrying blaOXA-51-like enzymes; however, the presence of multiple mechanisms did not result in increased resistance to carbapenems. There was no difference in the resistance mechanisms in strains from infected and colonized patients. The majority of strains were genetically diverse by DNA macrorestriction although there was evidence of clonal spread of four clusters of strains in patients.
authors.affiliation: Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Kim
authors.forename: S I
authors.initials: SI
authors.lastname: Kim
authors.forename: Y R
authors.initials: YR
authors.lastname: Kim
authors.forename: K W
authors.initials: KW
authors.lastname: Hong
authors.forename: S H
authors.initials: SH
authors.lastname: Wie
authors.forename: Y J
authors.initials: YJ
authors.lastname: Park
authors.forename: H
authors.initials: H
authors.lastname: Jeong
authors.forename: M W
authors.initials: MW
authors.lastname: Kang
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology*; D016009:Chi-Square Distribution; D016000:Cluster Analysis; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D008297:Male; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D017720:Molecular Epidemiology; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D018709:Statistics, Nonparametric; D013845:Thienamycins / Q000494:pharmacology; D018440:beta-Lactam Resistance
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D013845:Thienamycins; D015378:Imipenem; D000077731:Meropenem