Transcriptional expression of PmrB and arnA within polymyxin-resistant nosocomial isolates of Pseudomonas aeruginosa from India

Abstract

ABSTRACT
 
 Objective: The polymyxin group of antibiotics is considered to be
 one of the most effective antimicrobial agents against many serious pathogenic
 bacteria, but the excessive use of these antibiotics has led to the development
 of drug resistance among bacteria. This study was designed to characterize polymyxin-resistant
 P. aeruginosa and to explore the role
 of PmrB and arnA in resistant phenotype.
 
 Methods:
 mRNA and cDNA of five selected polymyxin-resistant strains representing
 different MIC range; isolated under normal condition of  strain growth, after treating sample/media
 with FeCl3 and MgCl2 alone, or after treating with FeCl3 and polymyxin
 antibiotic. The transcriptional expression was observed for PmrB and arnA by quantitative real time RT-PCR in reference to P. aeruginosa PAO1. The presence of
 plasmid mediated colistin resistance determinants mcr-1 was screened by PCR. Susceptibility of the strains was
 determined by disc-diffusion method and DNA fingerprinting was carried out by
 performing REP-PCR.
 
 Results: A
 down regulated expression of PmrB and
 arnA was observed even after the
 unique induction with FeCl3 and MgCl2. All the isolates were found to be
 resistant against cefepime and different clonal patterns of resistance were
 found among the isolates.
 
 Conclusion: This study has drawn a new insight into polymyxin
 resistance which will help in the detection and control of infections caused by
 multidrug resistant P. aeruginosa.
 The low susceptibility rate to aminoglycoside, piperacllin-tazobactam and
 ciprofloxacin was found and in addition, detection of PmrB and arnA as
 molecular markers in the follow up of infections caused by multidrug resistant P. aeruginosa. J Microbiol Infect Dis 2018; 8(2):61-68.