革蘭氏陰性菌如大腸埃希氏菌造成的細菌感染,，通常對于二種以上的抗生素具有抗藥性。由于使用新的抗生素無法消除多重抗藥性的問題,，所以這種類型的感染成為了重大的健康威脅,，特別是院內(nèi)感染的患者。
多重抗藥性成為了許多研究人員的研究目標,。最近由一組美國,、葡萄牙和法國科學家組成的研究小組,，辨認導致革蘭氏陰性菌多重抗藥性表型的基因事件順序。
這項研究名為「大腸桿菌的抗生素緊迫,、基因反應和改變的滲透性」將發(fā)表于4月11 日的Public Library of Science, PLoS ONE中,。
當大腸桿菌暴露于濃度越來越高的四圜素時，會使調(diào)控基因的活性越來越高,，而促進9種不同具排出功能的運輸?shù)鞍踪|(zhì)的基因表現(xiàn),，使抗生素達到作用的目標前，就被運出細菌之外,。
因活動同時進行的,，還包括隨著抗生素的緊迫增加，外膜的porin蛋白質(zhì)Omp F 和C會被蛋白酶分解并減少,，同時,，Omp x 的含量會持續(xù)地增加。
研究作者表示,，這是第一項研究證實,，長時間暴露于抗生素，會使細菌的排出泵浦表現(xiàn),，因此造成細菌的滲透性改變,。
(資料來源 : biocompare)
原始出處:
Antibiotic Stress, Genetic Response And Altered Permeability Of E. Coli
4/10/2007
Source: Public Library of Science
Bacterial infections caused by Gram-negative bacteria such as Escherichia coli are frequently resistant to two or more antibiotics (multi-drug resistant). Because introduction of new antibiotics will not eliminate the problem of multi-drug resistance (mdr), mdr type infections constitute a major health threat, especially to patients that acquire such infections nosocomially. The manner by which mdr develops has become an area of intense research and the recent investigations conducted by an international group consisting of American, Portuguese and French scientists have identified the genetic sequence of events that lead to mdr phenotypes of Gram-negative bacteria.
The study, entitled "Antibiotic Stress, Genetic Response and Altered Permeability of E. coli," will be published the 11th April issue of the international, peer-reviewed, open-access online journal of the Public Library of Science, PLoS ONE.
Briefly, prolonged exposure to increasing concentrations of tetracycline cause increased sequential activity of regulatory genes which promote over-expression of genes that code for as many as 9 transporter proteins of distinct efflux pumps which extrude unrelated antibiotics prior to their reaching their intended targets. Parallel to this genetic activity, whereas the level of outer membrane porin proteins Omp F and C decrease with increased antibiotic stress, the level of Omp X continues to increases dramatically. The decrease of Omp C and F appears to result from their being degraded by proteases inasmuch as the activity of genes that code for these proteins are also significantly elevated during prolonged antibiotic stress.
The authors of this study maintain that this is the first time that the response to prolonged exposure to increasing levels of antibiotic cause major changes in the permeability of the bacterium due to over-expression of efflux pumps and down-regulation of porins.
