Pseudomonas aeruginosa causes acute and chronic infections in humans and these infections are difficult to treat due to the bacteria’s high-level of intrinsic and acquired resistance to antibiotics. To address this problem, it is crucial to investigate the molecular mechanisms of antibiotic resistance in this organism. In this study, a P. aeruginosa transposon insertion library of 17000 clones was constructed and screened for altered susceptibility to seven antibiotics. Colonies grown on agar plates con- taining antibiotics at minimum inhibitory concentrations (MICs) and those unable to grow at ? MIC were collected. The transposon-disrupted genes in 43 confirmed mutants that showed at least a three-fold increase or a two-fold decrease in suscep- tibility to at least one antibiotic were determined by semi-random PCR and subsequent sequencing analysis. In addition to nine genes known to be associated with antibiotic resistance, including mexI, mexB and mexR, 24 new antibiotic resis- tance-associated genes were identified, including a fimbrial biogenesis gene pilY1 whose disruption resulted in a 128-fold in- crease in the MIC of carbenicillin. Twelve of the 43 genes identified were of unknown function. These genes could serve as targets to control or reverse antibiotic resistance in this important human pathogen.
Glutathione(GSH) plays important roles in pulmonary diseases,and inhaled GSH therapy has been used to treat cystic fibrosis(CF) patients in clinical trials.The results in this report revealed that GSH altered the sensitivity of Pseudomonas aeruginosa to different antibiotics through pathways unrelated to the oxidative stress as generally perceived.In addition,GSH and its oxidized form inhibited the growth of P.aeruginosa.
ZHANG YaNi & DUAN KangMin Molecular Microbiology Laboratory,the College of Life Sciences,Northwest University,Xi’an 710069,China
