RESUMO
The contribution of efflux pumps to multidrug resistance in 12 Pseudomonas aeruginosa isolates from various animal sources was assessed. Western immunoblot analyses demonstrated that all twelve isolates expressed significant levels of the MexAB OprM efflux system whereas two isolates simultaneously expressed the MexEF OprN or MexXY systems, respectively. One strain contained a single mutation in mexR, a regulator of mexAB-oprM expression, that did not adversely affect the MexR amino acid sequence, and three isolates contained the same, single base change in the mexA-mexR intergenic region. The MexXY-expressing strain contained two base substitutions in its mexZ regulatory gene which did not alter the MexR sequence.
Assuntos
Proteínas de Bactérias , Resistência Microbiana a Medicamentos/genética , Resistência a Múltiplos Medicamentos/genética , Proteínas de Membrana Transportadoras , Infecções por Pseudomonas/veterinária , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/genética , Proteínas Repressoras/genética , Sequência de Aminoácidos , Animais , Antibacterianos/farmacologia , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , Sequência de Bases , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Regulação Bacteriana da Expressão Gênica , Íntrons , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/isolamento & purificação , Proteínas Repressoras/química , Proteínas Repressoras/metabolismoRESUMO
Triclosan is an antiseptic frequently added to items as diverse as soaps, lotions, toothpaste, and many commonly used household fabrics and plastics. Although wild-type Pseudomonas aeruginosa expresses the triclosan target enoyl-acyl carrier protein reductase, it is triclosan resistant due to expression of the MexAB-OprM efflux system. Exposure of a susceptible Delta(mexAB-oprM) strain to triclosan selected multidrug-resistant bacteria at high frequencies. These bacteria hyperexpressed the MexCD-OprJ efflux system due to mutations in its regulatory gene, nfxB. The MICs of several drugs for these mutants were increased up to 500-fold, including the MIC of ciprofloxacin, which was increased 94-fold. Whereas the MexEF-OprN efflux system also participated in triclosan efflux, this antimicrobial was not a substrate for MexXY-OprM.
Assuntos
Antibacterianos/farmacologia , Anti-Infecciosos Locais/farmacologia , Proteínas de Bactérias/genética , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/metabolismo , Triclosan/farmacologia , Sequência de Aminoácidos , Proteínas da Membrana Bacteriana Externa/análise , Proteínas da Membrana Bacteriana Externa/genética , Resistência Microbiana a Medicamentos/genética , Genes MDR/genética , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , MutaçãoRESUMO
The genomes of the two clonally derived Pseudomonas aeruginosa prototypic strains PAO1 and DSM-1707 differ by the presence of a 2. 19-Mb inversion including oriC. Integration of two Flp recombinase target sites near the rrn operons containing the inversion endpoints in PAO1 led to Flp-catalyzed inversion of the intervening 1.59-Mb fragment, including oriC, at high frequencies (83%), favoring the chromosome configuration found in DSM-1707. The results indicate that the oriC-containing region of the P. aeruginosa chromosome can readily undergo and tolerate large inversions.