Institute of Milk Hygiene, Milk Technology and Food Science, Department of Veterinary Public Health and Food Science, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria.
Int J Food Microbiol. 2012 Jul 16;157(3):326-31. doi: 10.1016/j.ijfoodmicro.2012.04.023. Epub 2012 May 3.
For the first time it has been possible to determine the contamination level of Listeria monocytogenes in the very cheese lots of acid curd cheese that caused a multinational outbreak between 2009/2010. The listeriosis outbreak accounted for 34 clinical cases and eight deaths. The cheese, which was distributed in Austria, Germany, the Czech Republic, Poland and Slovakia, was recalled on the 23rd January 2010. All recalled lots were immediately investigated after call back from the retail market. The company manufactured two different cheese types, (i) red smear ripened--and (ii) mold coated/white veined--acid curd cheese. Depending on the lot production dates, cheese samples (n=1045) were analyzed at three different time points: (i) beginning to mid shelf-life (lot nos. 15-18; production period 5.1.2010-13.1.2010); (ii) end of shelf-life (lot nos. 9-18; production period 21.12.2009-13.1.2010) and, (iii) ≤46days after the expiry date (lot nos. 1-18; production period 1.12.2009-13.1.2010). Qualitative and quantitative examinations of cheese samples were performed according to ISO 11290-1&2. Examination of the samples, according to ISO 11290-1, resulted in 16 L. monocytogenes positive (red smear type) and two negative lots (mold coated type). These results were confirmed by a combined enrichment/real-time PCR method. The contamination values obtained by quantitative ISO 11290-2 varied from ≤log 2 cell forming units (CFU)/g to log 8.1CFU/g. Three out of sixteen L. monocytogenes positive lots revealed a contamination level of ≤log 2CFU/g at the beginning of their shelf-life when stored at 4°C. Nevertheless, by increasing the storage life and/or the storage temperature (15, 22°C) the contamination level could be raised to between log 5 and log 6CFU/g. Our data indicate that 81.3% (13/16) of the recalled red smear quargel cheese lots were highly contaminated with L. monocytogenes. All this implies that the main contamination of the quargel cheese took place during the red smear process and that quargel cheese can easily support growth of L. monocytogenes.
首次有可能确定导致 2009/2010 年间跨国李斯特菌病爆发的酸凝乳奶酪非常特定批次的污染水平。这次李斯特菌病爆发涉及 34 例临床病例和 8 例死亡。该奶酪曾在奥地利、德国、捷克共和国、波兰和斯洛伐克分销，于 2010 年 1 月 23 日召回。在从零售市场召回后，立即对所有召回的批次进行了调查。该公司生产了两种不同类型的奶酪，（i）红色涂抹成熟奶酪，和（ii）模制涂层/白色纹理奶酪。根据批次生产日期，在三个不同时间点对（n=1045）奶酪样本进行了分析：（i）货架寿命开始至中期（批次号 15-18；生产期 2010 年 5 月 1 日至 2010 年 1 月 13 日）；（ii）货架寿命结束时（批次号 9-18；生产期 2009 年 12 月 21 日至 2010 年 1 月 13 日）；和，（iii）保质期后≤46 天（批次号 1-18；生产期 2009 年 12 月 1 日至 2010 年 1 月 13 日）。根据 ISO 11290-1&2 对奶酪样本进行了定性和定量检测。根据 ISO 11290-1 的检测结果，16 个李斯特菌阳性（红色涂抹型）和 2 个阴性批次（模制涂层型）。这些结果通过组合增菌/实时 PCR 方法得到证实。通过定量 ISO 11290-2 获得的污染值范围从≤log 2 细胞形成单位（CFU）/g 至 log 8.1CFU/g。在 4°C 下储存时，16 个李斯特菌阳性批次中有 3 个在货架寿命开始时的污染水平为≤log 2CFU/g。然而，通过延长储存寿命和/或储存温度（15、22°C），污染水平可提高到 log 5 和 log 6CFU/g 之间。我们的数据表明，召回的红色涂抹夸格尔奶酪批次中有 81.3%（13/16）高度污染了李斯特菌。所有这些都表明，夸格尔奶酪的主要污染发生在红色涂抹过程中，并且夸格尔奶酪很容易支持李斯特菌的生长。
