Emergence of Escherichia coli, Co-Producing NDM-1 and OXA-48 Carbapenemases, in Urinary Isolates, at a Tertiary Care Centre at Central India

Objective: To detect genes encoding carbapenem resistance in urinary isolates of Escherichia coli recovered from hospitalized patients in tertiary care centre in Pune, India. Materials and Methods: From Jan 2012 to Dec 2012, a total of 300 consecutive non-duplicate (one isolate per patient) clinical isolates of Escherichia coli were recovered from urine cultures of hospitalized patients including hospital acquired infection cases admitted to the medical and surgical intensive care units. Polymerase chain reaction (PCR) assays and sequencing was used to determine the presence of beta-lactamase encoding genes. Conjugation experiments were performed to determine the transferability of beta-lactamase. Results: All the isolates were completely resistant to the second and third generation cephalosporins tested as well as carbapenems. All the isolates showed 100% susceptibility to tigecycline and colistin in vitro. Conjugation experiments demonstrated that bla(NDM-1) was transferable via plasmid. All the isolates showed presence of bla(NDM-1) and co-association of bla(OXA-48) was 25/45(55%) of the isolates. Repetitive element based PCR (REP PCR), Enterobacterial Repetitive Intergenic Consensus (ERIC PCR) and Randomly Amplified Polymorphic DNA (RAPD) revealed a diversity of six clonal types among E.coli isolates. Conclusion: Co-production of NDM-1 with OXA-48 in urinary isolates of E. coli was detected for the first time in India. Transmission of plasmid carrying these resistant genes to other members of Enterobacteriaceae will increase incidence of multidrug resistance. Early detection of these genes will help in prevention and adequate infection control by limiting the spread of these organisms.