Purpose: (i) To evaluate the hygienic level and (ii) to monitor the prevalence and spread of L. monocytogenes and Salmonella spp. in the plant environment and the final products of a meat industry over a 3 years period.
Methods: Environmental, raw material, and final product samples were collected during the past 3 years from a Greek meat processing industry with exports potential. Total viable counts (TVC), Escherichia coli, and total coliforms were enumerated on all samples. The presence of L. monocytogenes and Salmonella spp. was determined according to ISO 11290-1 and 6579:2002. Isolates of the two pathogens were serotyped using multiplex-PCR. Genotypic subtyping by PFGE was used to identify potential routes of cross-contamination and persistence.
Results: In total 2541 samples were analyzed in the period 2011-2013. The mean population of TVC, coliforms, and Escherichia coli was 5.6, 3.5, and 1.2 log CFU/g, respectively. Salmonella’s prevalence was 5.3% (134 positive samples) with 41.1% being S. Infantis. A total of 183 (7.2%) samples were found positive for L. monocytogenes. Of these 65.6% belonged to 1/2a, 25.2% to 1/2c, 3.9% to 1/2b and 5.5% to 4b serogroup. Utilization of molecular tools revealed several cross-contamination routes as indicated by the identification of same Salmonella and Listeria strains in different final products sharing same processing steps. Furthermore, the isolation of identical strains in different production lines and on personnel hands revealed straightforward cross-contamination scenarios. Finally, insufficient sanitizing procedures may favor the persistence of the pathogens as manifested by systematic isolation of certain strains within 8 months period.
Significance: Results may be used by the industry to i) evaluate hygiene of raw materials and suppliers and ii) reassess the hygiene practices of the personnel and the regular disinfection program, in order to improve the quality and safety of the final products. This work has been supported by the project “Efficacy of NOVEL analytical techniques to prEdict the quality and safetY of newly developed pErishable food products 11SYN_2_1528” co-financed by the European Union (European Social Fund – ESF) and Greek national funds through the O.P. “Competitiveness and Entrepreneurship (OPC II)” ROP Macedonia – Thrace, ROP Crete and Aegean Islands, ROP Thessaly – Mainland Greece – Epirus, ROP Attica, Framework NSRF 2007-2013, COOPERATION 2011.