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.
ABSTRACT
Background: Pseudomonas aeruginosa is one of the leading opportunistic pathogen and its ability to acquire resistance against series of antimicrobial agents confi ne treatment option for nosocomial infections. Increasing resistance to fl uroquinolone (FQ) agents has further worsened the scenario. The major mechanism of resistance to FQs includes mutation in FQs target genes in bacteria (DNA gyrase and/or topoisomerases) and overexpression of antibiotic effl ux pumps. Objective: We have investigated the role of effl ux pump mediated FQ resistance in nosocomial isolates of P. aeruginosa from a tertiary referral hospital in north eastern part of India. Materials and Methods: A total of 234 non-duplicate, consecutive clinical isolates of P. aeruginosa were obtained from a tertiary referral hospital of north-east India. An effl ux pump inhibitor (EPI), carbonyl cyanide m-chlorophenylhydrazone (CCCP) based method was used for determination of effl ux pump activity and multiplex polymerase chain reaction (PCR) was performed for molecular characterisation of effl ux pump. Minimum inhibitory concentration (MIC) reduction assay was also performed for all the isolates. Results and Conclusion: A total number of 56 (23%) have shown effl ux mediated FQ resistance. MexAB-OprM effl ux system was predominant type. This is the fi rst report of effl ux pump mediated FQ resistance from this part of the world and the continued emergence of these mutants with such high MIC range from this part of the world demands serious awareness, diagnostic intervention, and proper therapeutic option.