title: An unusual occurrence of plasmid-mediated blaOXA-23carbapenemase in clinical isolates of Escherichia coli from India.
abstract: The blaOXA-23group was considered as the first group of OXA-type β-lactamases conferring carbapenem resistance and has been reported worldwide in Acinetobacter baumannii, however their presence in Escherichia coli is very rare and unique. This study describes an unusual occurrence of blaOXA-23in 14 clinical isolates of E. coli obtained from intensive care unit patients admitted to a tertiary referral hospital in India. The blaOXA-23gene was found located within a self-conjugative plasmid of IncFrepB and IncK incompatibility types and simultaneously carrying blaCTX-M-15, blaVEB-1, blaPER-1and/or blaNDM-1. The copy number of blaOXA-23within the IncK-type plasmid was inversely proportional to increasing concentrations of imipenem, whereas in the case of the IncFrepB-type the result was variable; and increased copy number of the IncK-type plasmid was observed with increasing concentrations of meropenem. Plasmids encoding blaOXA-23could be successfully eliminated after single treatment and were found to be not highly stable, as complete loss of plasmids was observed within 5-10 days. This study emphasises that carbapenem stress invariably altered the copy number of two different Inc type plasmids encoding the blaOXA-23resistance gene and also highlights a potential threat of clonal expansion of this class D carbapenemase through a heterologous host in this country, which is in second incidence globally.
authors.affiliation: Department of Microbiology, Assam University, Silchar, India.
authors.forename: Deepjyoti
authors.initials: D
authors.lastname: Paul
authors.affiliation: Department of Microbiology, Assam University, Silchar, India.
authors.forename: Birson
authors.initials: B
authors.lastname: Ingti
authors.affiliation: Department of Statistics, Assam University, Silchar, India.
authors.forename: Dibyojyoti
authors.initials: D
authors.lastname: Bhattacharjee
authors.affiliation: Department of Microbiology, Assam University, Silchar, India.
authors.forename: Anand Prakash
authors.initials: AP
authors.lastname: Maurya
authors.affiliation: Department of Microbiology, Silchar Medical College and Hospital, Silchar, India.
authors.forename: Debadatta
authors.initials: D
authors.lastname: Dhar
authors.affiliation: Department of Microbiology, Silchar Medical College and Hospital, Silchar, India.
authors.forename: Atanu
authors.initials: A
authors.lastname: Chakravarty
authors.affiliation: Department of Microbiology, Assam University, Silchar, India. Electronic address: ab0404@gmail.com.
authors.forename: Amitabha
authors.initials: A
authors.lastname: Bhattacharjee
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D056915:DNA Copy Number Variations / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D018628:Gene Dosage / Q000235:genetics; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D007194:India; D007362:Intensive Care Units; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D010957:Plasmids / Q000235:genetics*; D062606:Tertiary Care Centers; D013845:Thienamycins / Q000494:pharmacology*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D013845:Thienamycins; D015378:Imipenem; C466679:beta-lactamase OXA-23; D001618:beta-Lactamases; C063912:carbapenemase; D000077731:Meropenem
keywords: Escherichia coli; ICU; Stability; bla(OXA-23)