Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
J Food Prot. 2013 May;76(5):883-7. doi: 10.4315/0362-028X.JFP-12-521.
In this study, 141 Cronobacter isolates that were collected based on a hygienic monitoring program performed in a powdered infant formula production facility in Switzerland between September 2011 and October 2012 were further characterized. Isolates were identified to the species level by molecular methods, and strains of Cronobacter sakazakii were further subtyped by applying PCR-based O-antigen serotyping, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE). C. sakazakii was the most prevalent species identified (93.6%). Among this collection of isolates, representatives of all but one O-antigen serotype (serotype O5) were recognized. MLST analysis of 19 selected isolates revealed that most of the typeable isolates belonged to sequence type (ST) 4. Correlations between ST4 and serotype O2 and between ST83 and serotype O7 were observed. PFGE analysis revealed clusters with multiple isolates, including strains from samples collected at different time points and sampling sources. Generally, the observed heterogeneity among strains collected over the 13 months of the monitoring program was high, suggesting a constant flux among strains rather than a selection for persisting organisms.
在这项研究中，对 2011 年 9 月至 2012 年 10 月期间在瑞士一家配方奶粉生产厂进行卫生监测计划所收集的 141 株克罗诺杆菌分离株进行了进一步的特征分析。通过分子方法将分离株鉴定到种的水平，并且通过应用基于 PCR 的 O-抗原血清分型、多位点序列分型 (MLST) 和脉冲场凝胶电泳 (PFGE)，对克罗诺杆菌属阪崎肠杆菌进行了进一步的亚型分型。最常见的鉴定物种是阪崎克罗诺杆菌 (93.6%)。在该分离株集合中，除了一种 O-抗原血清型 (血清型 O5) 外，均识别出所有的血清型。对 19 株选定分离株的 MLST 分析表明，大多数可分型分离株属于序列型 (ST)4。观察到 ST4 与血清型 O2 之间以及 ST83 与血清型 O7 之间的相关性。PFGE 分析显示存在多个分离株的聚类，包括来自不同时间点和采样来源的样本中的菌株。通常，在监测计划的 13 个月中收集的菌株之间观察到的异质性很高，这表明菌株之间存在持续不断的流动，而不是对持续存在的生物体的选择。
