24 25 Constitutive overproduction of the pump MexXY/OprM (XY+/M) is recognized as a major 26 cause of resistance to aminoglycosides, fluoroquinolones, and zwitterionic cephalosporins in 27 P. aeruginosa. In this study, 57 clonally-unrelated strains recovered from non-cystic fibrosis 28 patients were analyzed to characterize the mutations resulting in upregulation of the mexXY 29 operon. Forty f...

The emergence of multidrug-resistant Pseudomonas aeruginosa has become a serious problem in medical settings. P. aeruginosa clinical isolate PA7 is resistant to fluoroquinolones, aminoglycosides, and most β-lactams but not imipenem. In this study, enhanced efflux-mediated fluoroquinolone resistance of PA7 was shown to reflect increased expression of two resistance nodulation cell division (RND)...

BACKGROUND Mex efflux pumps contribute to multidrug resistance in Pseudomonas aeruginosa. Evidencing their expression in clinical isolates would help in rationalizing antibiotic selection. METHODS We have developed a combined phenotypic and genotypic approach for the differential diagnosis of resistance mediated by four major transporters (MexAB-OprM, MexCD-OprJ, MexEF-OprN, MexXY-OprM). The ...

To find the exact substrate specificities of three species of tripartite efflux systems of Pseudomonas aeruginosa, MexAB-OprM, MexCD-OprJ, and MexXY-OprM, we constructed a series of isogenic mutants, each of which constitutively overproduced one of the three efflux systems and lacked the other two, and their isogenic mutants, which lacked all these systems. Comparison of the susceptibilities of...

The aim of this study was to detect the expression of 4 clinically-important efflux pumps in the Resistance-Nodulation-Cell Division (RND) family including MexAB-OprM, MexXY, MexCD-OprJ and MexEF-OprN in Pseudomonas aeruginosa using a combination of resistance-phenotypic markers and multiplex RT-PCR (mRT-PCR). The antibiotic substrates specific for each Mex systems were used as phenotypic marke...

  Target modification and reduced drug accumulation are the main resistance mechanisms against fluoroquinolone antibiotics in Pseudomonas aeruginosa. We performed a genotypic characterization of three major Mex multidrug efflux pumps (MexAB-OprM, MexXY-OprM and MexCD-OprJ) in ciprofloxacin resistant clinical isolates of P. aeru­ginosa, collected from Tehran, Iran this was followed by sequencin...

One of the global health issues is antibiotic resistance in Pseudomonas aeruginosa, a causative agent bacterial infections due to multidrug (MDR), which may be mediated by efflux pumps' overexpression.The present study investigated prevalence mexXY-oprM, mexPQ-opmE genes as encoding agents pumps and determination rate clinical isolates P. aeruginosa.Different specimens infectious patients, such...

In a university hospital, time-series analysis revealed a significant relationship between antibiotic (aminoglycoside, fluoroquinolone, and cefepime) use and incidence of MexXY-OprM-overproducing Pseudomonas aeruginosa. In vitro experiments confirm that such mutants were readily selected from both PAO1 and clinical strains when grown in the presence of these antibiotics.

target modification and reduced drug accumulation are the main resistance mechanisms against fluoroquinolone antibiotics in pseudomonas aeruginosa. we performed a genotypic characterization of three major mex multidrug efflux pumps (mexab-oprm, mexxy-oprm and mexcd-oprj) in ciprofloxacin resistant clinical isolates of p. aeru­ginosa, collected from tehran, iran this was followed by sequencing a...