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underpin modern medicine; their use has reduced childhood mortality and increased life expectancy , and they are crucial for invasive surgery and treatments such as chemotherapy. However, the number of infections caused by multidrug-resistant bacteria is increasing globally, and the spectre of untreatable infections is becoming a reality. The most recent(More)
The mechanisms by which RND pumps contribute to pathogenicity are currently not understood. Using the AcrAB-TolC system as a paradigm multidrug-resistant efflux pump and Salmonella enterica serovar Typhimurium as a model pathogen, we have demonstrated that AcrA, AcrB, and TolC are each required for efficient adhesion to and invasion of epithelial cells and(More)
Comparative reverse transcription-PCR in combination with denaturing high-pressure liquid chromatography analysis was used to determine the levels of expression of soxS, marA, acrF, acrB, and acrD in multiple-antibiotic-resistant (MAR) Salmonella enterica serovar Typhimurium isolates and mutants of S. enterica serovar Typhimurium SL1344 with defined(More)
OBJECTIVES To study how disinfectants affect antimicrobial susceptibility and phenotype of Salmonella enterica serovar Typhimurium SL1,344. METHODS Wild-type strain SL1,344 and its isogenic gyrA mutant were passaged daily for 7 days in subinhibitory concentrations, and separately for 16 days in gradually increasing concentrations of a quaternary ammonium(More)
OBJECTIVES The aim of this study was to characterize the mechanisms of resistance to triclosan in Salmonella enterica serovar Typhimurium. METHODS Mutants resistant to triclosan were selected from nine S. enterica serovar Typhimurium strains. Mutants were characterized by genotyping, mutagenesis and complementation of fabI and analysis of efflux activity.(More)
It has been proposed that lack of a functional efflux system(s) will lead to a lower frequency of selection of resistance to fluoroquinolones and other antibiotics. We constructed five strains of Salmonella enterica serovar Typhimurium SL1344 that lacked efflux gene components of resistance nodulation cell division pumps (acrB, acrD, acrF, acrBacrF, and(More)
Salmonella enterica serovar Typhimurium SL1344, in which efflux pump genes (acrB, acrD, acrF, tolC) or regulatory genes thereof (marA, soxS, ramA) were inactivated, was grown in the presence of 240 antimicrobial and nonantimicrobial agents in the Biolog Phenotype MicroArray. Mutants lacking tolC, acrB, and ramA grew significantly worse than other mutants in(More)
OBJECTIVES Multiply antibiotic-resistant (MAR) mutants of Escherichia coli and Salmonella enterica are characterized by reduced susceptibility to several unrelated antibiotics, biocides and other xenobiotics. Porin loss and/or active efflux have been identified as a key mechanisms of MAR. A single rapid test was developed for MAR. METHODS The(More)
In previous work, Salmonella enterica serovar Typhimurium strain SL1344 was exposed to sublethal concentrations of three widely used farm disinfectants in daily serial passages for 7 days in an attempt to investigate possible links between the use of disinfectants and antimicrobial resistance. Stable variants OXCR1, QACFGR2, and TOPR2 were obtained(More)
OBJECTIVES To investigate the contribution of multidrug efflux pump systems of Salmonella enterica serovar Typhimurium to the formation of a competent biofilm. METHODS Biofilm formation by a wild-type strain and 10 efflux mutant strains was quantified using crystal violet biofilm assays and visualized using scanning electron microscopy. Curli expression(More)