Chlorate and disinfectant modify Salmonella enterica shedding in weaned pigs

The effects of chlorate administration, age at weaning (10 and 21 days), and topically applied disinfectant on Salmonella enterica shedding were evaluated in 80 weaned pigs naturally exposed to Salmonella positive dams. Salmonella spp were qualitatively detected in samples collected on post-weaning days (PWD) -2, 10 and 14 and the concentration estimated for samples collected PWD 0, 5 and for PWD 14 cecal content

Is the Evolution of Salmonella enterica subsp. enterica Linked to Restriction-Modification Systems?

Salmonella enterica subsp. enterica bacteria are highly diverse foodborne pathogens that are subdivided into more than 1,500 serovars. The diversity is believed to result from mutational evolution, as well as intra- and interspecies recombination that potentially could be influenced by restriction-modification (RM) systems. The aim of this study was to investigate whether RM systems were linked to the evolution of Salmonella enterica subsp. enterica. The study included 221 Salmonella enterica genomes, of which 68 were de novo sequenced and 153 were public available genomes from ENA. The data set covered 97 different serovars of Salmonella enterica subsp. enterica and an additional five genomes from four other Salmonella subspecies as an outgroup for constructing the phylogenetic trees. The phylogenetic trees were constructed based on multiple alignment of core genes, as well as the presence or absence of pangenes. The topology of the trees was compared to the presence of RM systems, antimicrobial resistance (AMR) genes, Salmonella pathogenicity islands (SPIs), and plasmid replicons. We did not observe any correlation between evolution and the RM systems in S. enterica subsp. enterica. However, sublineage correlations and serovar-specific patterns were observed. Additionally, we conclude that plasmid replicons, SPIs, and AMR were all better correlated to serovars than to RM systems. This study suggests a limited influence of RM systems on the evolution of Salmonella enterica subsp. enterica, which could be due to the conjugational mode of horizontal gene transfer in Salmonella. Thus, we conclude that other factors must be involved in shaping the evolution of bacteria. IMPORTANCE The evolution of bacterial pathogens, their plasticity and ability to rapidly change and adapt to new surroundings are crucial for understanding the epidemiology and public health. With the application of genomics, it became clear that horizontal gene transfer played a key role in evolution. To understand the evolution and diversification of pathogens, we need to understand the processes that drive the horizontal gene transfer. Restriction-modification systems are thought to cause rearrangements within the chromosome, as well as act as a barrier to horizontal gene transfer. However, here we show that the correlation between restriction-modification systems and evolution in other bacterial species does not apply to Salmonella enterica subsp. enterica. In summary, from this work, we conclude that other mechanisms might be involved in controlling and shaping the evolution of Salmonella enterica subsp. enterica

Inhibition of \u3cem\u3eListeria monocytogenes\u3c/em\u3e on Ready-to-Eat Meats Using Bacteriocin Mixtures Based on Mode-of-Action

Bacteriocin-producing (Bac+) lactic acid bacteria (LAB) comprising selected strains of Lactobacillus curvatus, Lactococcus lactis, Pediococcus acidilactici, and Enterococcus faecium and thailandicus were examined for inhibition of Listeria monocytogenes during hotdog challenge studies. The Bac+ strains, or their cell-free supernatants (CFS), were grouped according to mode-of-action (MOA) as determined from prior studies. Making a mixture of as many MOAs as possible is a practical way to obtain a potent natural antimicrobial mixture to address L. monocytogenes contamination of RTE meat products (i.e., hotdogs). The heat resistance of the bacteriocins allowed the use of pasteurization to eliminate residual producer cells for use as post-process surface application or their inclusion into hotdog meat emulsion during cooking. The use of Bac+ LAB comprising 3× MOAs directly as co-inoculants on hotdogs was not effective at inhibiting L. monocytogenes. However, the use of multiple MOA Bac+ CFS mixtures in a variety of trials demonstrated the effectiveness of this approach by showing a \u3e 2-log decrease of L. monocytogenes in treatment samples and 6–7 log difference vs. controls. These data suggest that surface application of multiple mode-of-action bacteriocin mixtures can provide for an Alternative 2, and possibly Alternative 1, process category as specified by USDA-FSIS for control of L. monocytogenes on RTE meat products

United States Food Manufacturer Assessment of and Responses to Bioengineered Foods

Food manufacturers routinely face decisions regarding the choice of ingredients and processes for producing foods. In the case of bioengineered foods, they must choose whether to produce foods not containing bioengineered ingredients and, in the near future, whether to produce foods containing ingredients enhanced through bioengineering. Food manufacturers' decisions regarding the use of bioengineered ingredients are influenced by the nature of the regulatory environment and both demand-side and supply-side considerations. This paper summarizes the current state of the domestic and foreign regulatory environments and results of interviews with food manufacturers about the demand-side and supply-side considerations affecting their decisions."Portions of this study were conducted for the U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition (FDA/CFSAN) by RTI, Center for Regulatory Economics and Policy Research, under Contract No. 223-96-2290, Task Order 12."Includes bibliographical reference