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Listeria monocytogenes (Lm) is a highly heterogeneous species. Researchers from China reported (Nature communications volume 10, Article number: 4283 (2019)) the detection of a highly virulent new form of pathogenic Listeria monocytogenes from sheep listeriosis outbreaks that represent a hybrid sub-lineage of the major lineage II (HSL-II) and serotype 4h. HSL-II. This new strain exhibit higher organ colonization capacity than other Listeria strains. The isolates harbor both the Lm Pathogenicity Island (LIPI)-1 and a truncated LIPI-2 locus, encoding sphingomyelinase (SmcL), a virulence factor required for invasion and bacterial translocation from the gut. Multi-locus sequence type (MLST) analysis revealed three isolates are members of an unidentified sequence type (ST) and clonal complex (CC). The discovery of isolates harboring pan-species virulence genes of the genus Listeria warrants global efforts to identify further hypervirulent lineages of Lm. @

The Canadian Food Inspection Agency notified The U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) that several shipments of beef implicated in a series of recalls have been exported to the U.S. and might be contaminated with E. coli O157:H7. As a result FSIS announced a public health alert for raw non-intact beef products derived from imported beef from Ontario, Canada that has been recalled by Ryding-Regency Meat Packers, Ltd. The products that are part of the Canadian recall and were distributed to institutions and retailers in Connecticut, Illinois, Maine, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont. FSIS has identified that imported beef manufacturing trimmings produced on May 27 and 30, 2019 that are subject to recall were used in the U.S. to produce other raw non-intact beef products distributed for retail sale. @ https://www.fsis.usda.gov/wps/portal/fsis/newsroom/news-releases-statements-and-tr...

An article by Cox et al. published in the Journal of Food Protection (October 2019, Vol. 82, No. 10, pp. 1688-1696) the researchers found that the choice enrichment medium and rinse procedure cause a bias in the type of Salmonella identified. The inability to assess serovar diversity means that serovars more often associated with human illness may be masked by more abundant Salmonella. Whole carcass pre-enrichment released more serovars than standard rinse aliquot pre-enrichment.  Serovar Schwarzengrund was present at higher frequencies in whole carcass pre-enrichment compared with rinse aliquot pre-enrichment, suggesting it adheres more strongly to the carcass. Selective enrichment in Rappaport-Vassiliadis (RV)  or tetrathionate (TT)  was inhibitory to some serovars.  Salmonella Enteritidis is selected in tetrathionate broth; Salmonella Schwarzengrund is selected in Rappaport-Vassiliadis broth.  @ https://www.ncbi.nlm.nih.gov/pubmed/31536420

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Researchers from the USDA published in Food Control a study of predictive models to determine the risk of Salmonella in ground beef. They used a cocktail of six strains, five serovars of Salmonella enterica to inoculate raw ground beef, and follow bacterial growth and survival at 1 to 47 °C during storage. The data was used to develop predictive models that can more accurately estimate bacterial growth and survival for both salmonella and background microflora (microbiota). The data showed that above 17.3 °C, Salmonella would grow faster than the background microbiota. The data from the study helped develop a more accurate risk assessment model for Salmonella in raw ground beef during storage and temperature abuse. @ https://www.sciencedirect.com/science/article/pii/S0956713519304347?dgcid=rss_sd_all