Case of contamination by Listeria monocytogenes in mozzarella cheese

• Published in: Italian journal of food safety Vol. 3; no. 1
• Main Authors: Greco, Sara, Tolli, Rita, Bossù, Teresa, Flores Rodas, Eda Maria, Di Giamberardino, Fabiola, Di Sirio, Alessandro, Vita, Silvia, De Angelis, Veronica, Bilei, Stefano, Sonnessa, Michele, Gattuso, Antonietta, Lanni, Luigi
• Format: Journal Article
• Language: English
• Published: PAGEPress Publications, Pavia, Italy 04.03.2014; PAGEPress Publications
• Subjects: Listeria monocytogenes, Mozzarella, PFGE, Serotypes; Short Communication
• ISSN: 2239-7132; 2239-7132
• DOI: 10.4081/ijfs.2014.1708

Following a Listeria monocytogenes detection in a mozzarella cheese sampled at a dairy plant in Lazio Region, further investigations have been conducted both by the competent Authority and the food business operatordairy factory (as a part of dairy factory HACCP control). In total, 90 dairy products, 7 brine and 64 environmental samples have been tested. The prevalence of Listeria monocytogenes was 24.4% in mozzarella cheese, and 9.4% in environmental samples, while brines were all negatives. Forty-seven strains of L. monocytogenes have been isolated, all belonging to 4b/4e serotype. In 12 of these, the macrorestriction profile has been determined by means of pulsed field gel electrophoresis. The profiles obtained with Asc I enzyme showed a 100% similarity while those obtained with Apa I a 96.78% similarity. These characteristics of the isolated strains jointly with the production process of mozzarella cheese has allowed to hypothesise an environmental contamination.