Co-existence of beta-lactamases in clinical isolates of Escherichia coli from Kathmandu, Nepal

Abstract

Background: The trend of extended-spectrum beta-lactamases producing Escherichia coli (ESBL-EC) is increasing in Nepal. Limited studies have been reported investigating ESBL types and carbapenemases in E. coli. Methods. A cross sectional study was conducted between June 2012 to January 2013 in Kathmandu Medical College and Teaching Hospital, Nepal. Non-repetitive clinical samples from out-patient department (OPD) and Intensive Care Units (ICU) were processed for bacteriological culture and identification of E. coli. Antibiotic susceptibility test, screening and phenotypic confirmation for ESBLs and carbapenemases and PCR (bla CTX-M, bla SHV and bla TEM-type ESBLs, bla VIM, bla IMP and bla NDM-1-type carbapenemases, and class 1 integron element integrase gene) were performed. Clones were resolved by PCR-Randomly Amplified Polymorphic DNA. Results: Out of 332 non-repetitive clinical specimens processed for culture and identification 160 (48.2%) were culture positive. Of which, 93 (58.1%) were E. coli. Of these, 24 (25.8%) were phenotypically confirmed as ESBL-EC and 3 (12.50%) of 24 ESBL-EC were carbapenemase producers. bla CTX-M-type ESBL was most common (23, 95.8%) followed by bla TEM (7, 29.2%) and bla SHV (3, 12.5%). bla VIM, bla IMP and bla NDM-1 were present in 3, 2 and 2 ESBL-EC, respectively. Class 1 integron element was present in 18 (75.0%) ESBL-EC. Nine isolates possessed more than one type of beta-lactamases. Interestingly, all carbapenemase producers were isolated form ICU and co-existence of bla CTX-M, bla SHV, bla TEM, bla IMP, bla VIM and bla NDM-1 beta-lactamases was documented in one ESBL-EC (EC104). All most all isolates had different RAPD patterns. Conclusions: For the first time in Nepal, high prevalence of bla CTX-M-type ESBL and co-existence of ESBLs and carbapenemases has been described. Continuous monitoring and surveillance and proper infection control and prevention practices will limit the further spread of these super-bugs within this hospital and beyond.