title: Characterization of plasmids in extensively drug-resistant acinetobacter strains isolated in India and Pakistan.
abstract: The blaNDM-1 gene is associated with extensive drug resistance in Gram-negative bacteria. This probably spread to Enterobacteriaceae from Acinetobacter spp., and we characterized plasmids associated with blaNDM-1 in Acinetobacter spp. to gain insight into their role in this dissemination. Four clinical NDM-1-producing Acinetobacter species strains from India and Pakistan were investigated. A plasmid harboring blaNDM-1, pNDM-40-1, was characterized by whole-genome sequencing of Acinetobacter bereziniae CHI-40-1 and comparison with related plasmids. The presence of similar plasmids in strains from Pakistan was sought by PCR and sequencing of amplicons. Conjugation frequency was tested and stability of pNDM-40-1 investigated by real-time PCR of isolates passaged with and without antimicrobial selection pressure. A. bereziniae and Acinetobacter haemolyticus strains contained plasmids similar to the pNDM-BJ01-like plasmids identified in Acinetobacter spp. in China. The backbone of pNDM-40-1 was almost identical to that of pNDM-BJ01-like plasmids, but the transposon harboring blaNDM-1, Tn125, contained two short deletions. Escherichia coli and Acinetobacter pittii transconjugants were readily obtained. Transconjugants retained pNDM-40-1 after a 14-day passage experiment, although stability was greater with meropenem selection. Fragments of pNDM-BJ01-like plasmid backbones are found near blaNDM-1 in some genetic contexts from Enterobacteriaceae, suggesting that cross-genus transfer has occurred. pNDM-BJ01-like plasmids have been described in isolates originating from a wide geographical region in southern Asia. In vitro data on plasmid transfer and stability suggest that these plasmids could have contributed to the spread of blaNDM-1 into Enterobacteriaceae.
authors.affiliation: Cardiff University, Cardiff School of Medicine, University Hospital of Wales, Cardiff, United Kingdom Public Health Wales Microbiology Cardiff, University Hospital of Wales, Cardiff, United Kingdom JonesLS5@cardiff.ac.uk.
authors.forename: Lim S
authors.initials: LS
authors.lastname: Jones
authors.affiliation: Cardiff University, Cardiff School of Medicine, University Hospital of Wales, Cardiff, United Kingdom.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Carvalho
authors.affiliation: Cardiff University, Cardiff School of Medicine, University Hospital of Wales, Cardiff, United Kingdom.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Toleman
authors.affiliation: Public Health Wales Microbiology Cardiff, University Hospital of Wales, Cardiff, United Kingdom.
authors.forename: P Lewis
authors.initials: PL
authors.lastname: White
authors.affiliation: Cardiff University, Cardiff School of Biosciences, Cardiff, United Kingdom.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Connor
authors.affiliation: Dow University of Health Sciences, Dow Medical College, Karachi, Pakistan.
authors.forename: Ammara
authors.initials: A
authors.lastname: Mushtaq
authors.affiliation: Cardiff University, Cardiff School of Medicine, University Hospital of Wales, Cardiff, United Kingdom.
authors.forename: Janis L
authors.initials: JL
authors.lastname: Weeks
authors.affiliation: Department of Microbiology, Dr ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Chennai, India.
authors.forename: Karthikeyan K
authors.initials: KK
authors.lastname: Kumarasamy
authors.affiliation: University of Cambridge, Department of Medicine, Addenbrooke's Hospital, Cambridge, United Kingdom.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Raven
authors.affiliation: University of Cambridge, Department of Medicine, Addenbrooke's Hospital, Cambridge, United Kingdom.
authors.forename: M Estée
authors.initials: ME
authors.lastname: Török
authors.affiliation: University of Cambridge, Department of Medicine, Addenbrooke's Hospital, Cambridge, United Kingdom Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Sharon J
authors.initials: SJ
authors.lastname: Peacock
authors.affiliation: Cardiff University, Cardiff School of Medicine, University Hospital of Wales, Cardiff, United Kingdom Public Health Wales Microbiology Cardiff, University Hospital of Wales, Cardiff, United Kingdom.
authors.forename: Robin A
authors.initials: RA
authors.lastname: Howe
authors.affiliation: Cardiff University, Cardiff School of Medicine, University Hospital of Wales, Cardiff, United Kingdom.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Walsh
mesh_terms: D000150:Acinetobacter / Q000187:drug effects / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D007194:India; D008826:Microbial Sensitivity Tests; D010154:Pakistan; D010957:Plasmids / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents