Distribution of Class II integrons and their contribution to antibiotic resistance within Enterobacteriaceae family in India

Abstract

Background: Integrons are the main contributors to the development of multidrug resistance (MDR) among Gram-negative bacilli. There is a lack of knowledge about the molecular relation between gene cassettes and antibiotic resistance in India.

Objective: In this study, we have investigated the occurrence of Class II integron and their cassette array among Enterobacteriaceae.

Materials and methods: A total of 268 MDR non-duplicate strains of Enterobacteriaceae were collected from Silchar Medical College and Hospital, Silchar, Assam, India, during June 2012 to May 2013. Polymerase chain reaction was performed for detection of the integrase genes and gene cassettes within the Class II integron which were further analysed by sequencing.

Results: Class II integron was observed in 47 isolates. Four different gene cassette arrangements were detected: dfrA1-sat2-aadA1; dfrA1-sat2-aadA1-orfX-ybeA-ybfA-ybfB-ybgA; dfrA12-sat2-aadA1; and dfrA1-linF-aadA1. The most prevalent cassette combination was dfrA1-sat2-aadA1. This study has also identified a set of gene cassette associated with linF gene instead of sat2 gene.

Conclusion: Further investigation is required to determine the current situation and important reservoir of Class II integron for the transmission of drug resistance among Enterobacteriaceae and their contribution to antimicrobial resistance in hospital environment .