Hein Ingeborg, Gadzov Boris, Schoder Dagmar, Foissy Helmut, Malorny Burkhard, Wagner Martin
Institute for Milk Hygiene, Milk Technology and Food Science, University of Veterinary Medicine Vienna, Austria.
Foodborne Pathog Dis. 2009 Mar;6(2):225-33. doi: 10.1089/fpd.2008.0175.
A milk powder processing line was sampled for the presence of Enterobacteriaceae and the opportunistic neonatal pathogen Cronobacter at six different sampling sites during an 11-month period. The highest number of Enterobacteriaceae-positive samples was recovered from the raw milk concentrate before pasteurization (78.2%) and from nonproduct samples of the processing line (86.5%), which included swabs from the drying tower and screw conveyers, swabs from the explosion chamber, waste water after the automated cleaning-in-place procedure, air filter cut-outs, and floor samples underneath the outlet of the packaging machine. The prepackaged and packaged final product was contaminated at a rate of 6.6% and 7.1%, respectively. The prevalence of Cronobacter in the prefinal product and the prepackaged and packaged final product was 14.3%, 3.8%, and 2.1%, respectively. Pulsed-field gel electrophoresis (PFGE) analysis of 133 Cronobacter isolates yielded 40 different PFGE profiles. Long-term persistence in the processing line of some of these PFGE profiles was observed. Comparison of the PFGE profiles recovered at different sampling sites revealed the supply air as a potential source for extrinsic Cronobacter contamination. In addition, recovery of the same PFGE profiles before and after CIP events followed by heat treatment indicated the inefficiency of these hygiene measures to completely eliminate Cronobacter from all areas of the processing line. This information provides an essential basis for developing control and prevention strategies concerning this opportunistic pathogen.
在11个月的时间里，对一条奶粉加工生产线的六个不同采样点进行了采样，以检测肠杆菌科细菌和机会性新生儿病原体阪崎肠杆菌的存在情况。在巴氏杀菌前的原料奶浓缩物中（78.2%）以及生产线的非产品样本中（86.5%），检测出的肠杆菌科阳性样本数量最多，非产品样本包括来自干燥塔和螺旋输送机的拭子、来自爆炸室的拭子、自动在位清洗程序后的废水、空气过滤器切口以及包装机出口下方的地面样本。预包装和包装后的最终产品污染率分别为6.6%和7.1%。阪崎肠杆菌在预成品以及预包装和包装后的最终产品中的检出率分别为14.3%、3.8%和2.1%。对133株阪崎肠杆菌分离株进行脉冲场凝胶电泳（PFGE）分析，得到了40种不同的PFGE图谱。观察到其中一些PFGE图谱在生产线中具有长期持续性。对不同采样点回收的PFGE图谱进行比较，发现送风是阪崎肠杆菌外部污染的潜在来源。此外，在在位清洗事件后进行热处理前后回收相同的PFGE图谱，表明这些卫生措施无法完全消除生产线所有区域的阪崎肠杆菌。这些信息为制定针对这种机会性病原体的控制和预防策略提供了重要依据。
