短短兩個月內，李斯特菌污染在美國已經導致16起不同的食品安全召回事件發生。為什么李斯特菌會出現在與細菌沒有直接關聯的產品中呢?一名美國堪薩斯州立大學的食品安全專家Fadi Aramouni給出了解釋。

　　“李斯特菌是一類在濕冷條件下發現的細菌”，這位來自美國堪薩斯州立大學的食品科學推廣專家說，”它的不同之處在于這種類型的細菌能夠在冷藏條件下生長并繁殖“。

　　李斯特菌通常在即食的熟肉制品和熱狗、冷藏肉制品、未經高溫消毒的牛奶和乳制品、用未經高溫消毒的牛奶制成的軟奶酪、冷凍的煙熏海產品以及生豆芽中存在。

　　根據美國食品藥品監督管理局的消息，自今年3月以來，16種可能含有李斯特菌的食品已被召回，包括鷹嘴豆、冷凍菠菜、沙冰等，最值得注意的是冰淇淋。

　　“冰激凌行業已經很長一段時間沒有因為李斯特菌污染而發生過食品安全問題了，主要原因是由于其高溫過程能夠殺死存在的病原體，” Aramouni說， “然而，如果生產現場沒有遵循嚴格的衛生操作規程， 那么李斯特菌可能也會存在于生產環境中，因為它能夠在濕冷的條件下存活， 比如在管道中或者天花板、燈架上的冷凝水滴中，都可能發現它的存在。”

　　他還指出，冰激凌中的李斯特菌也可能來自于添加的食品配料中。

　　““對于冰淇淋的生產，人們可能不知道，會有一部分原料被加入以后，不再經過高溫消毒過程了，”他說，“工人將牛奶高溫消毒并制成冰淇淋以后，他們還會添加像餅干面團或山核桃之類的東西。但這之后，冰淇淋就被放置在冰箱中，也不再經過任何其他類型的殺菌消毒措施，所以，如果附加的原材料被污染，李斯特菌就會在這個過程中存活下來。”

　　不幸的是，現在沒有辦法能夠讓消費者知道是否某種食品中是否受到李斯特菌的污染。但是， Aramouni說也不必過于擔心 ，只要關注食品安全召回信息，將列入召回目錄的產品做退貨處理或者直接扔掉就可以了，畢竟消費這樣的食品是非常危險的。

　　談到李斯特菌的危害性，Aramouni教授指出：“這種細菌能夠導致死亡，特別是對于老年人、孕婦、兒童和免疫力低下的人群來說。他們感染了李斯特菌后，會有大約75%的人住進醫院，而死亡率能夠達到25%，這個比例是非常高的。所以不要冒險，如果發生食品召回事件，要積極應對 ，不要食用那些召回的產品。”

　　編譯： 食安中國網

　　原文如下：

　　Listeria contamination has caused 16 different recalls in just two months, and a Kansas State University food safety specialist has an explanation about why it is appearing in products typically not associated with the bacteria.

　　“Listeria is a group of bacteria that is found in cold, wet environments,” said Fadi Aramouni, Ph.D., Extension specialist and professor of food science. “What’s unusual about this type of bacterium is they actually grow and multiply under refrigerated conditions.”

　　?Listeria is typically found in ready-to-eat deli meats and hot dogs, refrigerated meat spreads, unpasteurized milk and dairy products, soft cheese made with unpasteurized milk, refrigerated smoked seafood, and raw sprouts.

　　According to the Food and Drug Administration, 16 different food products potentially containing Listeria have been recalled since March, including products such as hummus, frozen spinach, smoothie kits and, most notably, ice cream.

　　“A Listeria contamination in ice cream hasn’t happened for a very long time because the pasteurization process kills the pathogen,” Aramouni said. “However, Listeria may survive in the environment if there are not good sanitation procedures in place. Because it survives in cold, wet environments, it can be found in drains or other areas of condensation within a plant, such as the ceiling or light fixtures.”

　　He says the Listeria in ice cream also could be coming from the added ingredients.

　　“One of the things people may not know about ice cream is that it is not pasteurized after the inclusions are put in,” he said. “After they pasteurize the milk and make the ice cream, they add things like cookie dough or pecans. The ice cream is then placed in the freezer and does not go through any other type of pasteurization, so if the additional products are contaminated, Listeriamay survive that process.”

　　Unfortunately, there is no way for consumers to tell if a product is contaminated with Listeria. But Aramouni said not to panic. Instead, pay close attention to food recalls and return the product or throw it out if it has been recalled because consuming the product can be dangerous.

　　“This bacterium can be deadly, especially for older adults, pregnant women, young children and people with weakened immune systems,” he explained. “About 75 percent of these individuals who get listeriosis end up in the hospital, and about 25 percent of them die, so it is quite virulent for this group. Don’t take chances. Anytime there’s a recall, respect that recall and do not consume the food.”