沙門(mén)氏菌是“一塊硬骨頭”

沙門(mén)氏菌是非常重要的食物源性病原體，但其在環(huán)境中生存繁衍的機(jī)制尚未完全清楚。本次美國(guó)西部禽病大會(huì)上，來(lái)自加州大學(xué)獸醫(yī)學(xué)院的Bart Weiner就沙門(mén)氏菌如何存活及如何減少其含量的問(wèn)題做了有關(guān)報(bào)告。

沙門(mén)氏菌有一套有效的機(jī)制來(lái)保證其在環(huán)境中存活并繁衍，能引起人類腸道疾病，對(duì)酸、過(guò)氧化物、熱和高滲透環(huán)境都有抵抗性。最近Weiner和他的同事試圖研究環(huán)境壓力對(duì)沙門(mén)氏菌存活率的影響，為降低沙門(mén)氏菌含量尋找新的方法。

冷和酸的應(yīng)激試驗(yàn)

在最初的實(shí)驗(yàn)中，專家們假設(shè)從動(dòng)物宿主到自然環(huán)境的轉(zhuǎn)移過(guò)程中，沙門(mén)氏菌能夠在低溫中存活很長(zhǎng)時(shí)間。試驗(yàn)結(jié)果表明，沙門(mén)氏菌可以在低溫中存活336小時(shí)，在這段時(shí)間內(nèi)，48小時(shí)后存活率有所降低；然而在5攝氏度時(shí)，240小時(shí)后仍然存在大量活菌。沙門(mén)氏菌在過(guò)氧化物、高滲液體、酸環(huán)境中，分別于0.5小時(shí)后和5小時(shí)后對(duì)其采樣，結(jié)果顯示只有過(guò)氧化物能夠顯著降低其存活率。

另外，研究者還用6種益生元、5種益生菌對(duì)沙門(mén)氏菌存活率進(jìn)行實(shí)驗(yàn)。每種益生元對(duì)沙門(mén)氏菌存活率，及其對(duì)宿主細(xì)胞的粘附力的影響都各不相同。比如，有一種MOS（甘露寡糖）會(huì)特異性地增強(qiáng)傷寒沙門(mén)氏菌對(duì)宿主細(xì)胞的粘附性。研究者還添加乳酸菌，檢測(cè)沙門(mén)氏菌粘附性是否降低，結(jié)果顯示，雙歧桿菌可以降低沙門(mén)氏菌對(duì)上皮細(xì)胞的粘附力。

這些關(guān)于沙門(mén)氏菌抗壓機(jī)制的新發(fā)現(xiàn)，有助于減少沙門(mén)氏菌活體污染環(huán)境，進(jìn)一步減少沙門(mén)氏菌對(duì)人類和動(dòng)物感染和疫情爆發(fā)。該研究全文已發(fā)表于應(yīng)用環(huán)境微生物學(xué)雜志（Applied and Environmental Microbiology）。

據(jù)悉:北京磐石頂冠動(dòng)物藥業(yè)有限公司出品的“健體寶”含高酶雙歧活芽胞桿菌、乳酸菌、活菌總數(shù)高達(dá)≥2x10⁸CFU/g。

因此：筆者建議在日常種鴿保健護(hù)理時(shí)，定期添加北京磐石頂冠動(dòng)物藥業(yè)公司出品的“健體寶”和“智慧油”拌料濕喂，可減少種鴿感染沙門(mén)氏菌的感染發(fā)病幾率。

Stress treatments show that Salmonella is a tough cookie

Salmonella is an important food born pathogen but its mechanisms to survive in the environment are still partly unclear. Speaking at the Western Poultry Disease Conference (WPDC), Bart Weiner from the School of Veterinary Medicine, University of California presented new work on how Salmonella enteritidis survival can be reduced.

Salmonella have efficient mechanisms to survive processing and persist in the environment to cause gastrointestinal disease in humans. Salmonella are well document to survive acid, peroxide, osmotic and heat stress with many of the genes responsible for the survival well defined. In the recent work from Weiner and his collegues they wanted to examine the way environmental stress influenced the survival rate of Salmonella and find novel ways - such as adding pre- and probiotics - to reduce the survival rate of this bacterium.

Cold and acid stress

The initial experiment examined the ability of Salmonella to survive cold stress for at least 336 hours to test the hypothesis that Salmonella can withstand long periods of exposure to low temperatures during the transition between animal hosts and the environment. It was shown that Salmonella survived cold stress for at least 336 hours. During the time course, survival declined after 48 hours, while at 5 degress Celcius a significantly high number of viable bacteria were observed after 240 hours. Exposure to peroxide, osmotoc and acid for 0.5 hours (shock) and 5 hours (stress) was examined to find that only peroxide shock significanlty reduced survival.

Feed additives

Next to the stress treatments, the research team examined six prebiotic and five probiotic treatments. A dose response was observed with each prebiotic, but each treatment had an unique effect on Salmonella adhesion of stressed cells. For example, a certain MOS type encouraged adesion of Salmonella enteriditis beyond that of the control. Addition of probiotic lactic acid bacteria was tested to reduce adhesion. Bifidobacterium infantis was shown to have a beneficial effect on epithelial cells.

These new insights in the underlying mechanisms os stress resistance and host association will provide additional strategies to further reduce Salmonella viability to limit transmit in the environment and reduce infections and further outbreaks of Salmonella in the animal and human population. This research will be published as a full paper in the journal: Applied and Environmental Microbiology.

The Western Poultry Disease Conference is beng held for the 60th time and takes place in Sacramento, California, from 20 till 23 March.