Abstract
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 markers including carbenicillin, MexAB-OprM, erythromycin, MexCD-OprJ, norfloxacin and imipenem, MexEF-OprN and gentamicin, MexXY-OprM. The methods were validated with reference strains with known genotypes of the Mex systems and the potential applicability in clinical practice was tested with clinical isolates. The results for the reference strains support that the combination of resistance phenotype and mRT-PCR is a potential-attractive method for diagnosis of efflux-mediated resistance in P. aeruginosa. Further development to make it more practical for clinical use and study in a larger number of clinical isolates is required.
Highlights
Pseudomonas aeruginosa, a common cause of nosocomia infections is infamous for its resistance to multipleHow to cite this paper: Poonsuk, K. and Chuanchuen, R. (2014) Detection of the Mex Efflux Pumps in Pseudomonas aeruginosa by Using a Combined Resistance-Phenotypic Markers and Multiplex RT-PCR
Five antibiotics were used as resistance-phenotypic markers for 4 clinically-important Mex systems tested in this study: carbenicillin, MexAB-OprM; erythromycin, MexCD-OprJ; norfloxacin and imipenem, MexEF-OprN and gentamicin, MexXY-OprM
Most of the clinical isolates exhibited higher resistance level to all antibiotics tested than PAO1 did
Summary
Pseudomonas aeruginosa, a common cause of nosocomia infections is infamous for its resistance to multipleHow to cite this paper: Poonsuk, K. and Chuanchuen, R. (2014) Detection of the Mex Efflux Pumps in Pseudomonas aeruginosa by Using a Combined Resistance-Phenotypic Markers and Multiplex RT-PCR. Chuanchuen drugs [1] that is mainly attributed to the synergy between the low outer membrane permeability and the expression of multidrug efflux systems, in the Resistance-Nodulation-Cell Division (RND) family [2]. The P. aeruginosa genome contains at least 12 structural genes for the RND efflux systems, of which four are clinically-important (i.e. MexABOprM, MexCD-OprJ, MexEF-OprN and MexXY) [2]. Due to their constitutive expression, MexAB-OprM and MexXY contribute to intrinsic resistance to many antibiotics [2]. MexCD-OprJ and MexEF-OprN do not express wild-type cells, but can overexpress after the acquisition of regulatory mutations, resulting in acquired multidrug resistance [4] [5]. Coexpression of Mex systems has been reported in the P. aeruginosa clinical isolates where its variable impact on antibiotic susceptibility has been observed [6]-[8]
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