Analýza zdrojů a cest šíření L. monocytogenes v prostředí mlékárenského podniku vyrábějícího zrající sýry
2009
The aim of this study was to identificate contamination routes of L. monocytogenes (LM) in smeared ripened cheeses on one dairy plant in the Czech Republic with the use of typing methods. During the year 2007 (july-december) 205 samples from the manufacturing environment were collected. A total of 8 final product samples originating from retail outlets were tested. In the year 2009 a study on the possible carriage of LM in 118 human samples acquired from the personnels of this dairy plant was realized. EN ISO 11290-1, 2 methods were used for detection and enumeration of LM. Titre of anti-bodies against LM was monitored in blood samples of selected workers. LM isolates were characterized by serotyping and macrorestriction analysis after digestion with the restriction enzyme AscI. LM was detected in 18,8% (27/144) swabs from manufacturing line. The forming machine was the most frequent place of positive findings. 72,7% isolates of LM (8/11) were detected on the chassis of this machine. 33,3% (6/18) positive findings were located on the conveyer belt of the forming machine coming into the direct contact with the food product. 96,3% (26/27) acquired isolates belonged to the serotype 1/2a and to the identical pulsotype (713). This pulsotype was detected as well in 25% samples of ripened cheeses originating from the retail outlets. However, LM was present in these samples at counts lower than 102 CFU.g-1. LM (throat swabs) even anti-bodies (blood serum) were not present in any of the clinical samples. Just one positive finding from a glove of the personnel confirms the hypothesis, that final products were contaminated mainly from the contact surfaces of the manufacturing line.
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