Expansion of highly stable blaOXA-10 β-lactamase family within diverse host range among nosocomial isolates of Gram-negative bacilli within a tertiary referral hospital of Northeast India

Anand Prakash Maurya, Debadatta Dhar, Mridul Kumar Basumatary, Deepjyoti Paul, Birson Ingti, Debarati Choudhury, Anupam Das Talukdar, Atanu Chakravarty, Shweta Mishra, Amitabha Bhattacharjee

The current study reports dissemination of highly stable bla OXA-10 family of beta lactamases among diverse group of nosocomial isolates of Gram-negative bacilli within a tertiary referral hospital of the northern part of India. In the current study, a total number of 590 Gram negative isolates were selected for a period of 1 year (i.e. 1st November 2011-31st October 2012). Members of Enterobacteriaceae and non fermenting Gram negative rods were obtained from Silchar Medical College and Hospital, Silchar, India. Screening and molecular characterization of β-lactamase genes was done. Integrase gene PCR was performed for detection and characterization of integrons and cassette PCR was performed for study of the variable regions of integron gene cassettes carrying bla OXA-10. Gene transferability, stability and replicon typing was also carried out. Isolates were typed by ERIC as well as REP PCR. Twenty-four isolates of Gram-negative bacilli that were harboring bla OXA-10 family (OXA-14, and OXA16) with fact that resistance was to the extended cephalosporins. The resistance determinant was located within class I integron in five diverse genetic contexts and horizontally transferable in Enterobacteriaceae, was carried through IncY type plasmid. MIC values were above break point for all the tested cephalosporins. Furthermore, co-carriage of bla CMY-2 was also observed. Multiple genetic environment of bla OXA-10 in this geographical region must be investigated to prevent dissemination of these gene cassettes within bacterial population within hospital settings.