Characterisation of fluoroquinolone resistance mechanisms in clinical isolates of enterobacteriaceae pseudomonas aeruginosa and acinetobacter baumannii

Abstract

Fluoroquinolones are synthetic antimicrobial agents with broad spectrum of activity They are used for the treatment of respiratory tract infections including tuberculosis urinary tract infections intraabdominal infections skin infections sexually transmitted diseases and bone and joint infections Their widespread and often indiscriminate use has resulted in ubiquitous resistance especially among members of Enterobacteriaceae Pseudomonas aeruginosa and Acinetobacter baumannii The purpose of this study was to characterize fluoroquinolone resistance in clinical isolates of Enterobacteriaceae P aeruginosa and A baumannii newline newlineDisc diffusion technique was used to screen isolates for fluoroquinolone resistance and to determine the co resistance to other antimicrobials Minimum inhibitory concentration was determined by agar dilution method for ciprofloxacin Efflux pump activity was evaluated using carbonyl cyanide m chlorophenylhydrazone The presence of quinolone resistance determining region genes and plasmid mediated quinolone resistance genes were screened by PCR Transferability of PMQR genes was determined by conjugation experiment and plasmid based replicon typing was performed Real time RT PCR was performed to detect the expression of efflux pump genes newlineA total of 463 ciprofloxacin resistant non-repetitive Enterobacteriaceae and Pseudomonas aeruginosa and Acinetobacter baumannii were included The degree of resistance among clinical isolates was high with MIC 64 microgram per ml in half of the isolates Among the mediators of resistance plasmid mediated resistance is the most common followed by chromosomally mediated mutations and efflux pumps Of chromosomal mutation genes gyrA and Aminoglycoside acetyltransferase among PMQR gene are the most common The successful transfer of plasmids coding for resistance was suggestive of the transfer potential and spread by plasmids Plasmid incompatible group IncFII was the most common plasmid type carrying fluoroquinolone resistance This is a cause for alarm since these plasmids have