The RND chromosomal systems are encoded by operons and are typically formed by three proteins, which are located in the inner membrane, periplasm and outer membrane of the bacterial cell [5]. Sequencing of P. aeruginosa genome
revealed the presence of several RND efflux systems. Of those, MexAB-OprM, MexCD-OprJ, MexEF-OprN and MexXY-OprM are able to pump out multiple antipseudomonal compounds [1, 4, 6]. Studies with MexAB-OprM mutants {Selleck Anti-diabetic Compound Library|Selleck Antidiabetic Compound Library|Selleck Anti-diabetic Compound Library|Selleck Antidiabetic Compound Library|Selleckchem Anti-diabetic Compound Library|Selleckchem Antidiabetic Compound Library|Selleckchem Anti-diabetic Compound Library|Selleckchem Antidiabetic Compound Library|Anti-diabetic Compound Library|Antidiabetic Compound Library|Anti-diabetic Compound Library|Antidiabetic Compound Library|Anti-diabetic Compound Library|Antidiabetic Compound Library|Anti-diabetic Compound Library|Antidiabetic Compound Library|Anti-diabetic Compound Library|Antidiabetic Compound Library|Anti-diabetic Compound Library|Antidiabetic Compound Library|Anti-diabetic Compound Library|Antidiabetic Compound Library|Anti-diabetic Compound Library|Antidiabetic Compound Library|Anti-diabetic Compound Library|Antidiabetic Compound Library|buy Anti-diabetic Compound Library|Anti-diabetic Compound Library ic50|Anti-diabetic Compound Library price|Anti-diabetic Compound Library cost|Anti-diabetic Compound Library solubility dmso|Anti-diabetic Compound Library purchase|Anti-diabetic Compound Library manufacturer|Anti-diabetic Compound Library research buy|Anti-diabetic Compound Library order|Anti-diabetic Compound Library mouse|Anti-diabetic Compound Library chemical structure|Anti-diabetic Compound Library mw|Anti-diabetic Compound Library molecular weight|Anti-diabetic Compound Library datasheet|Anti-diabetic Compound Library supplier|Anti-diabetic Compound Library in vitro|Anti-diabetic Compound Library cell line|Anti-diabetic Compound Library concentration|Anti-diabetic Compound Library nmr|Anti-diabetic Compound Library in vivo|Anti-diabetic Compound Library clinical trial|Anti-diabetic Compound Library cell assay|Anti-diabetic Compound Library screening|Anti-diabetic Compound Library high throughput|buy Antidiabetic Compound Library|Antidiabetic Compound Library ic50|Antidiabetic Compound Library price|Antidiabetic Compound Library cost|Antidiabetic Compound Library solubility dmso|Antidiabetic Compound Library purchase|Antidiabetic Compound Library manufacturer|Antidiabetic Compound Library research buy|Antidiabetic Compound Library order|Antidiabetic Compound Library chemical structure|Antidiabetic Compound Library datasheet|Antidiabetic Compound Library supplier|Antidiabetic Compound Library in vitro|Antidiabetic Compound Library cell line|Antidiabetic Compound Library concentration|Antidiabetic Compound Library clinical trial|Antidiabetic Compound Library cell assay|Antidiabetic Compound Library screening|Antidiabetic Compound Library high throughput|Anti-diabetic Compound high throughput screening| demonstrated that this efflux system extrudes quinolones, aminoglycosides, BV-6 in vitro macrolides, tetracycline, chloramphenicol, novobiocin, and most β-lactams but not imipenem [5]. The MexXY-OprM is able to eject cefepime, cefotaxime, levofloxacin, GANT61 price ciprofloxacin, amikacin, gentamicin, tobramycin, erythromycin, tetracycline and meropenem [5]. MexAB-OprM and MexXY-OprM are constitutively expressed and contribute to the intrinsic resistance phenotype
of P. aeruginosa. However, when overexpressed, these efflux systems confer reduced susceptibility to different classes of antimicrobial agents [7, 8]. Although the efflux systems MexCD-OprJ and MexEF-OprN are quiescent in wild type P. aeruginosa, their overexpression may also contribute to the acquired multi-drug resistance phenotype in mutant isolates [5]. Overexpression of efflux systems generally confers modest levels of antimicrobial resistance [9, 10]. However, its association with other resistance determinants Diflunisal is frequently observed [11]. In Brazil, production of extended-spectrum β-lactamases (ESBL), such as CTX-M (cefotaximase) and GES (Guiana-extended spectrum), or metallo-β-lactamases (MBL) such as SPM (São Paulo Metallo-β-lactamase) and IMP (imipenemase) are the main mechanisms of acquired resistance to broad-spectrum β-lactams
among P. aeruginosa clinical isolates [12]. The association of these β-lactamases with overexpression of efflux pumps and/or porin loss may lead to high level and/or co-resistance phenotypes [11]. For this reason, efflux pumps may seriously impact antimicrobial therapy in clinical settings. The aim of this study was to investigate the expression of efflux systems as well as its association with other resistance mechanisms, such as β-lactamase production and porin down-regulation, among P. aeruginosa clinical isolates. Results Bacterial isolates and antimicrobial susceptibility profile Fifty-nine non-repetitive P. aeruginosa isolates were collected from bloodstream infections between June and December 2005. The majority of isolates was collected from patients hospitalized in intensive care units (64.4%), followed by the emergency room ward (28.8%) and pediatric oncology unit (6.8%).