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Margret Oethinger
Tufts University
22Publications
11H-index
1,920Citations
Publications 16
Newest
#1Margret OethingerH-Index: 11
#2Stuart B. LevyH-Index: 78
L'invention concerne des techniques et des compositions representant un progres dans la lutte contre la resistance microbienne a l'action des medicaments. On a decouvert des pompes d'ecoulement de type AcrAB pour lutter contre la resistance a l'action des medicaments, meme dans le cas de microbes tres resistants. L'invention concerne egalement des techniques de traitement d'infection, des techniques de criblage d'inhibiteurs de pompes d'ecoulement de type AcrAB, et des techniques permettant d'am...
#1Margret OethingerH-Index: 11
#2Stuart B. LevyH-Index: 78
#1Winfried V. KernH-Index: 42
#2Margret Oethinger (Tufts University)H-Index: 11
Last.Stuart B. Levy (Tufts University)H-Index: 78
view all 4 authors...
Mutations in loci other than genes for the target topoisomerases of fluoroquinolones, gyrA and parC, may play a role in the development of fluoroquinolone resistance in Escherichia coli. A series of mutants with increasing resistance to ofloxacin was obtained from an E. coli K-12 strain and five clinical isolates. First-step mutants acquired a gyrA mutation. Second-step mutants reproducibly acquired a phenotype of multiple antibiotic resistance (Mar) and organic solvent tolerance and showed enha...
116 CitationsSource
#1Margret OethingerH-Index: 11
#2Winfried V. KernH-Index: 42
Last.Stuart B. Levy (Tufts University)H-Index: 78
view all 5 authors...
Fluoroquinolone-resistant mutants, selected from a wild-type Escherichia coli K-12 strain and its Mar mutant by exposure to increasing levels of ofloxacin on solid medium, were analyzed by Northern (RNA) blot analysis, sequencing, and radiolabelled ciprofloxacin accumulation studies. Mutations in the target gene gyrA (DNA gyrase), the regulatory gene marR, and additional, as yet unidentified genes (genes that probably affect efflux mediated by the multidrug efflux pump AcrAB) all contributed to ...
183 CitationsSource
#1Margret OethingerH-Index: 11
Last.W. V. KernH-Index: 17
view all 5 authors...
Escherichia coli with high-level fluoroquinolone resistance were isolated from feces and/or various body sites of 16 cancer patients who were on oral fluoroquinolone prophylaxis. Population analysis of fecal isolates in 11 patients showed that fluoroquinoloneresistantE. coli was the only aerobic gram-negative bacillus present and exhibited a relatively homogenous fluoroquinolone MIC distribution. Molecular typing by pulsed field gel electrophoresis of chromosomal DNA digests or by random amplifi...
23 CitationsSource
#1Laura M. McMurry (Tufts University)H-Index: 24
#2Margret Oethinger (Tufts University)H-Index: 11
Last.Stuart B. Levy (Tufts University)H-Index: 78
view all 3 authors...
Triclosan (Irgasan) is a broad spectrum antimicrobial agent used in handsoaps, toothpastes, fabrics, and plastics. It inhibits lipid biosynthesis in Escherichia coli, probably by action upon enoyl reductase (FabI) (McMurry L.M., Oethinger M. and Levy S.B. (1988) Nature 394, 531–532). We report here that overexpression of the multidrug efflux pump locus acrAB, or of marA or soxS, both encoding positive regulators of acrAB, decreased susceptibility to triclosan 2-fold. Deletion of the acrAB locus ...
283 CitationsSource
The contribution of regulatory genes to fluoroquinolone resistance was studied with clinical Escherichia coli strains bearing mutations in gyrA and parC and with different levels of fluoroquinolone resistance. Expression of marA and soxS was evaluated by Northern blot analysis of isolates that demonstrated increased organic solvent tolerance, a phenotype that has been linked to overexpression of marA , soxS , and rob . Among 25 cyclohexane-tolerant strains detected by a screen for increased orga...
129 CitationsSource
#1Laura M. McMurry (Tufts University)H-Index: 24
#2Margret Oethinger (Tufts University)H-Index: 11
Last.Stuart B. Levy (Tufts University)H-Index: 78
view all 3 authors...
Triclosan is a broad-spectrum antibacterial and antifungal agent1,2, which acts by previously undetermined mechanisms, that is used in products such as antiseptic soaps, toothpastes, fabrics and plastics. Here we show that triclosan blocks lipid synthesis in Escherichia coli, and that mutations in, or overexpression of, the gene fabI (which encodes enoyl reductase, involved in fatty acid synthesis) prevents this blockage. This is, to our knowledge, the first evidence that triclosan acts on a spe...
790 CitationsSource
Fluoroquinolone resistance in Escherichia coli is principally caused by two kinds of muta tion: those affecting the target proteins of the drugs, i.e. DNA gyrase and topoisomerase IV, and those affecting regulatory genes such as marA, soxS or robA. Recently, overexpression of the latter genes was linked to increased organic solvent tolerance in E. coli. Among 138 clinical fluoroquinolone-resistant and -susceptible clinical isolates of E. coli we found a high association between fluoroquinolone r...
37 CitationsSource
Previous reports have suggested an increasing incidence of highly fluoroquinolone-resistant Escherichia coli causing bacteremia among cancer patients on prophylactic therapy. We used genotyping by pulsed-field gel electrophoresis of chromosomal DNA digests and random amplified polymorphic DNA fingerprinting to study clonal relationships among such isolates obtained at 10 cancer centers located across Europe and the Middle East. Analysis by both methods indicated that isolates from different cent...
48 CitationsSource
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