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Schlegelová J., Babák V., Holasová M., Konstantinová L., Necidová L., Šišák F., Vlková H., Roubal P., Jaglic Z. (2010): Microbial contamination after sanitation of food contact surfaces in dairy and meat processing plants. Czech J. Food Sci., 28: 450-461.The occurrence of listeria monocytogenes, Salmonella spp., Bacillus cereus, Staphylococcus spp., enterococcus spp., and escherichia coli in raw food materials, food products, and on food contact surfaces after sanitation was investigated during the period of 2005-2006 in three dairy cattle farms (120 samples), one dairy (124 samples), and two meat processing plants (160 samples). A total of 1409 isolates were identified. The epidemiological characterisation and determination of the virulence factors and antimicrobial resistance were performed on selected isolates. The level of bacterial contamination generally decreased during the production process (the contamination of food products was lower than that of raw material). However, the contamination of food contact surfaces was relatively high even after sanitation. Moreover, specific microbiological profiles were found on the inside equipment surfaces in dairy facilities, where genetically closely related multi-resistant strains persisting in biofilm communities may occur as demonstrated for staphylococci. Although the occurrence of potentially significant pathogens was not high, the microorganisms such as l. monocytogenes, Salmonella spp., and shiga-toxin positive e. coli principally contaminated the meat processing plants. B. cereus isolates, among which 76% were positive for diarrhogenic enterotoxin, typically occurred on the inside equipment surfaces and in the heat-treated products.

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A survey to estimate the prevalence of verotoxigenic E. coli (VTEC) or enterohaemorrhagic E. coli (EHEC) in rectal swabs from healthy dairy cattle aged three weeks, three months and one year was conducted in three herds from the Czech Republic. Screening for the presence of the stx1, stx2 and eaeA genes in faecal swab cultures was performed by PCR, and in positive samples, isolated colonies were examined. Immunomagnetic separation was used for the isolation of the VTEC serogroup O157 from samples. VTEC were detected in animals from all three herds under study. In the group of 3-week-old calves, VTEC were only detected in samples collected in the summer months. However, in the other age-groups, VTEC were detected in both the summer and winter months. EHEC shedding was observed in 30 to 100% of the total samples collected from cattle aged three months and one year in the summer months, and in 30 to 60% of samples taken in the winter months. EHEC strains of serogroup O157 were detected in two herds. The range of verotoxins shed by VTEC isolates of serogroup O157 differed between herds. Besides serogroup O157, additional EHEC belonging to the antigen groups O26, O103, O128 and O153 have been identified, and in some of them, no somatic antigen was detected.

EnterotoxigenicEscherichia coliis an important enteric pathogen causing post-weaning diarrhoea in piglets. Enterotoxins ofE. coliinduce the release of fluid into the intestines without apparent inflammation. Some serotypes ofE. coli, especially O149:F4 can often be identified in association with haemorrhagic gastroenteritis. In this study we infected the weaned piglets (n = 53) by oral administration of enterotoxigenicE. coliO149:F4 strains isolated from piglets suffering from haemorrhagic gastroenteritis. The clinical course of infection and shedding of the challengeE. colistrain in the faeces of infected piglets was monitored for 14 days. The challenge strain soon outnumbered the otherE. colitypes in the intestines of most piglets. Diarrhoea developed in the majority of piglets and its severity varied. Severe diarrhoea was observed in 10% of the piglets but only one piglet died due to dehydration. No inflammatory lesions were detected in the intestines of the dead piglet and the other euthanized piglets. We assume that development of haemorrhagic gastroenteritis depends on the involvement of other factors that need to be identified.E. coliO149:F4 are only one of the causative factors of haemorrhagic gastroenteritis in piglets after weaning.