大量的細(xì)菌會通過市政設(shè)施進(jìn)入環(huán)境中，尤其是醫(yī)院的廢水,。盡管廢水處理廠的處理減少了總的細(xì)菌數(shù)量，但是對于多重耐藥細(xì)菌并不能殺滅,，近日,，研究者Eawag在洛桑日內(nèi)瓦湖城開展的一項研究揭示了多重耐藥細(xì)菌的存在。洛桑市大約每天處理90000立方米的污水,，全部排放到日內(nèi)瓦湖的海灣處,，排放點長700米，深30米,。洛桑市所處理的廢水不僅僅是來自居民的,，而且來自沃州大學(xué)醫(yī)院（CHUV）。先前有研究者證實了廢水中抗生素耐藥性的流行,，因此,，研究者們的目的是調(diào)查是否抗性基因也進(jìn)入了環(huán)境之中，尤其是經(jīng)過處理的污水中是否含有細(xì)菌的抗性耐藥基因,。相關(guān)成果刊登在了近日的國際雜志Frontiers Microbiology上,。
研究者使用傳統(tǒng)的方法和精細(xì)的遺傳分析方法，第一種樣品測試程序依據(jù)瑞士標(biāo)準(zhǔn),，研究者的測定結(jié)果符合預(yù)期,，在CHUV的廢水中發(fā)現(xiàn)了高水平的耐藥細(xì)菌。研究結(jié)果令人驚訝,，經(jīng)過廢水處理廠之后,，超過75%的細(xì)菌都被殺滅了，可是剩下的耐藥菌株仍然可以在廢水中繁殖,，從而使得細(xì)菌水平升高,。微生物學(xué)家Burgmann表示，經(jīng)過 污水處理廠處理,，細(xì)菌的抗性基因很有可能會進(jìn)行轉(zhuǎn)移,，細(xì)菌間可以通過高水平的群體感應(yīng)信號分子來轉(zhuǎn)移移動的遺傳元件，細(xì)菌吸納抗性基因并不罕見,，而且對細(xì)菌自身并不會產(chǎn)生任何危害,。我們以前并不知道，湖水中的耐藥基因的水平非常高,，尤其是在沉積物中的耐藥基因的水平和未處理過的污水中水平幾乎一樣,。因此，耐藥基因可以在致病菌之間相互轉(zhuǎn)移,，不光在湖水中是這樣,，在人體中，和抗生素耐藥性相關(guān)的移動遺傳元件也會通過喝水等過程進(jìn)行轉(zhuǎn)移。
研究者Nadine Czekalski表示,，我們飲水的深井一般離污水排出點有3公里之遙,，但是在水井周圍的沉積物中研究者也發(fā)現(xiàn)了耐藥基因的存在，盡管如此,，我們也不必驚慌,，湖中的水在進(jìn)入飲水循環(huán)系統(tǒng)中必須經(jīng)過嚴(yán)格的處理。但是研究者提醒大家仍需要謹(jǐn)慎,，而且在研究者看來,，政府應(yīng)當(dāng)介入此事，在處理污水的時候,，應(yīng)當(dāng)加大措施,，不僅僅出去微量污染物，而且也應(yīng)當(dāng)除去抗藥性的微生物,。而且對于醫(yī)院的廢水,，必須經(jīng)過分離嚴(yán)格處理。
關(guān)于多重耐藥性
研究者用多重耐藥菌來描述對多種抗生素均有抗性的細(xì)菌,，這些細(xì)菌頻繁接觸多種抗生素以及重金屬,、消毒劑。環(huán)境性釋放帶來的多重耐藥細(xì)菌的存在是我們必須關(guān)注的一個問題,，從長遠(yuǎn)來講,，環(huán)境中這些耐藥基因的流行性會增加，通過移動遺傳元件轉(zhuǎn)移耐藥基因,，這就增加了致病菌中攜帶耐藥基因的風(fēng)險,，給公眾的健康帶來了巨大的威脅。（生物谷：T.Shen編譯）
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doi:10.3389/fmicb.2012.00106
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Increased levels of multiresistant bacteria and resistance genes after wastewater treatment and their dissemination into Lake Geneva, Switzerland
Nadine Czekalski1*, Tom Berthold2, Serena Caucci2, Andrea Egli1 and Helmut Bürgmann1
At present, very little is known about the fate and persistence of multiresistant bacteria (MRB) and their resistance genes in natural aquatic environments. Treated, but partly also untreated sewage of the city of Lausanne, Switzerland is discharged into Vidy Bay (Lake Geneva) resulting in high levels of contamination in this part of the lake. In the present work we have studied the prevalence of MRB and resistance genes in the wastewater stream of Lausanne. Samples from hospital and municipal raw sewage, treated effluent from Lausanne’s wastewater treatment plant (WTP) as well as lake water and sediment samples obtained close to the WTP outlet pipe and a remote site close to a drinking water pump were evaluated for the prevalence of MRB. Selected isolates were identified (16S rRNA gene fragment sequencing) and characterized with regards to further resistances, resistance genes, and plasmids. Mostly, studies investigating this issue have relied on cultivation-based approaches. However, the limitations of these tools are well known, in particular for environmental microbial communities, and cultivation-independent molecular tools should be applied in parallel in order to take non-culturable organisms into account. Here we directly quantified the sulfonamide resistance genes sul1 and sul2 from environmental DNA extracts using TaqMan real-time quantitative PCR. Hospital sewage contained the highest load of MRB and antibiotic resistance genes (ARGs). Wastewater treatment reduced the total bacterial load up to 78% but evidence for selection of extremely multiresistant strains and accumulation of resistance genes was observed. Our data clearly indicated pollution of sediments with ARGs in the vicinity of the WTP outlet. The potential of lakes as reservoirs of MRB and potential risks are discussed.
