title: Molecular epidemiology and antimicrobial resistance phenotypes of Acinetobacter baumannii isolated from patients in three hospitals in southern Vietnam.
abstract: Multidrug resistance in the nosocomial pathogen Acinetobacter baumannii limits therapeutic options and impacts on clinical care. Resistance against carbapenems, a group of last-resort antimicrobials for treating multidrug-resistant (MDR) A. baumannii infections, is associated with the expression (and over-expression) of carbapenemases encoded by the blaOXA genes. The aim of this study was to determine the prevalence of antimicrobial-resistant A. baumannii associated with infection in three hospitals in southern Vietnam and to characterize the genetic determinants associated with resistance against carbapenems. We recovered a total of 160 A. baumannii isolates from clinical samples collected in three hospitals in southern Vietnam from 2012 to 2014. Antimicrobial resistance was common; 119/160 (74 %) of isolates were both MDR and extensively drug resistant (XDR). High-level imipenem resistance (>32 µg ml-1) was determined for 109/117 (91.6 %) of the XDR imipenem-nonsusceptible organisms, of which the majority (86.7 %) harboured the blaOXA-51 and blaOXA-23 genes associated with an ISAba1 element. Multiple-locus variable number tandem repeat analysis segregated the 160 A. baumannii into 107 different multiple-locus variable number tandem repeat analysis types, which described five major clusters. The biggest cluster was a clonal complex composed mainly of imipenem-resistant organisms that were isolated from all three of the study hospitals. Our study indicates a very high prevalence of MDR/XDR A. baumannii causing clinically significant infections in hospitals in southern Vietnam. These organisms commonly harboured the blaOXA-23 gene with ISAba1 and were carbapenem resistant; this resistance phenotype may explain their continued selection and ongoing transmission within the Vietnamese healthcare system.
authors.affiliation: Diagnostic Department, Faculty of Nursing and Medical Technology, University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam.
authors.forename: Nguyen
authors.initials: N
authors.lastname: Tuan Anh
authors.affiliation: The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.
authors.forename: Tran Vu Thieu
authors.initials: TVT
authors.lastname: Nga
authors.affiliation: Infection Control Department, University Medical Center, Ho Chi Minh City, Vietnam.
authors.forename: Huynh Minh
authors.initials: HM
authors.lastname: Tuan
authors.affiliation: Microbiology Department, Thong Nhat-Dong Nai General Hospital, Dong Nai Province, Vietnam.
authors.forename: Nguyen Si
authors.initials: NS
authors.lastname: Tuan
authors.affiliation: Microbiology Department, Dong Nai General Hospital, Dong Nai Province, Vietnam.
authors.forename: Dao Minh
authors.initials: DM
authors.lastname: Y
authors.affiliation: The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.
authors.forename: Nguyen Van
authors.initials: NV
authors.lastname: Vinh Chau
authors.affiliation: Centre for Tropical Medicine, Oxford University, Oxford, UK.|The Department of Medicine, The University of Cambridge, Cambridge, UK.|The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.
authors.forename: Stephen
authors.initials: S
authors.lastname: Baker
authors.affiliation: Department of Genetics, Faculty of Biology, University of Science, Ho Chi Minh City, Vietnam.
authors.forename: Ho Huynh Thuy
authors.initials: HHT
authors.lastname: Duong
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology* / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000235:genetics* / Q000302:isolation & purification; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015780:Carbapenems / Q000494:pharmacology; D016000:Cluster Analysis; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D005260:Female; D006761:Hospitals; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D010641:Phenotype; D015995:Prevalence; D020080:Tandem Repeat Sequences; D014744:Vietnam / Q000453:epidemiology; D055815:Young Adult; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D004269:DNA, Bacterial; D015378:Imipenem; D001618:beta-Lactamases; C063912:carbapenemase