A study published in the ASM journal “Microbiology Spectrum” used WGS to provide insights into two species of presumed nonpathogenic Listeria innocua and L. welshimeri and found that they are developing a surprising number of characteristics that are potentially harmful to humans. The study used a comparative genome approach to analyze 41 genome sequences belonging to L. innocua and L. welshimeri isolated from food and food processing facilities. Genetic determinants responsible for disinfectant and stress tolerance were identified, including the efflux cassette bcrABC and Tn6188_qac_1 disinfectant resistance determinant and stress survival islets. These disinfectant-resistant genes were more frequently found in L. innocua (12%) than in L. welshimeri (2%). Several isolates representing the presumed nonpathogenic L. innocua still carried virulence-associated genes absent in all L. welshimeri isolates. The results suggest that the presumed nonpathogenic isolates, especially L. innocua can carry genes relevant to the strain’s virulence and stress tolerance in food processing facilities. The presence of genetic loci previously associated with adaption/survival in stressful conditions was higher in L. innocua, especially L. innocua ST132, than in any of the L. welshimeri strains. Some strains of L. innocua and L. welshimeri examined in the study show three genes for resistance to a widely-used disinfectant from the quaternary ammonium compounds. The study highlights that the low occurrence of important core genes could result from a functional CRISPR-cas system in the Listeria genomes. @ https://journals.asm.org/doi/10.1128/spectrum.01189-22
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The UK authorities published in JFP (January 2023) a study on two foodborne outbreaks caused by contaminated imported melon. Between March and July 2021, there was an outbreak of 113 cases of Salmonella Braenderup in the UK (62% female, median age 61 years, 33% hospitalized). Galia melons from Honduras were identified as the vehicle of infection. Subsequently, the outbreak strain was isolated from two samples of Galia melon imported from Latin America. In July and August 2021, there was an outbreak of 17 cases of STEC O157:H7 in the UK (53% female, median age 21 years, 35% were hospitalized). A questionnaire implicated eating precut watermelon from a retailer as the source of infection. In outbreaks associated with fresh fruit, due to the difficulty in removing pathogens from the fruit’s flesh, efforts should focus on preventing microbial contamination from production to processing to distribution. @ https://www.sciencedirect.com/science/article/pii/S0362028X22000394
Food Safety magazine reported that the FDA has worked with the EPA to modify the list of organisms required for developing and registering antimicrobial treatments for preharvest agricultural water, removing Listeria monocytogenes from the test panel. The change to the protocol is being made due to pilot studies suggesting that sanitizers that are likely effective for Escherichia coli and Salmonella may be different from those that are most effective for L. monocytogenes. Due to recent outbreaks of E. coli (STEC) and Salmonella linked to produce, the FDA and EPA agreed and decided to remove L. monocytogenes from the panel. FDA expects that the change will facilitate the registration of antimicrobial treatments against STEC, other E. coli, and Salmonella in preharvest agricultural water, the availability of which will be a significant resource for farms to protect their crops against such pathogens. @ https://www.food-safety.com/articles/8257-fda-removes-listeria-from-test-panel-for-preharvest-ag-water-treatments-protocol
The U.S. Food and Drug Administration (FDA) has worked with the U.S. Environmental Protection Agency (EPA) to update the protocol for the development and registration of antimicrobial treatments for preharvest agricultural water, removing Listeria monocytogenes from the organism test panel.
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A study conducted at North Carolina University and published in JFP aimed to determine the prevalence and degree of cross-contamination across various kitchen surfaces during a consumer meal preparation event. Consumers (n = 371) prepared a meal consisting of turkey patties containing the bacteriophage MS2 as a tracer organism and a ready-to-eat lettuce salad. For most surfaces, positivity did not exceed 20%, except spice containers, for which 48% of the samples showed evidence of MS2 cross-contamination. Spice containers also had the highest MS2 concentrations. The most highly contaminated surfaces were the spice containers, cutting board, and trash bin lid. The result suggests the significance of spice containers as a vehicle for cross-contamination.
The results presented in this study provide deeper knowledge about how cross-contamination occurs in home kitchens. @ https://meridian.allenpress.com/jfp/article/85/11/1594/486035/Cross-Contamination-to-Surfaces-in-Consumer
ABSTRACT. It is estimated that one in five cases of foodborne illnesses is acquired in the home. However, how pathogens move throughout a kitchen environment when consumers are preparing food is not well characterized. The purpose of this study was to determine the prevalence and degree of cross-contamination across a variety of kitchen surfaces during a consumer meal preparation event. Consumers (n = 371) prepared a meal consisting of turkey patties containing the bacteriophage MS2 as a tracer organism and a ready-to-eat lettuce salad. Half were shown a video on proper thermometer use before the trial. After meal preparation, environmental sampling and detection were performed to assess cross-contamination with MS2. For most surfaces, positivity did not exceed 20%, with the exception of spice containers, for which 48% of the samples showed evidence of MS2 cross-contamination. Spice containers also had the highest MS2 concentrations, at a mean exceeding 6 log viral genome equivalent copies per surface. The high level of MS2 on spice containers drove the significant differences between surfaces, suggesting the significance of spice containers as a vehicle for cross-contamination, despite the absence of previous reports to this effect. The thermometer safety intervention did not affect cross-contamination. The efficiency of MS2 transfer, when expressed as a percentage, was relatively low, ranging from an average of 0.002 to 0.07%. Quantitative risk assessment work using these data would aid in further understanding the significance of cross-contamination frequency and efficiency. Overall, these data will help create more targeted consumer messaging to better influence consumer cross-contamination behaviors.HIGHLIGHTSForty-eight percent of spice containers sampled showed evidence of MS2 cross-contamination.Spice containers had the highest MS2 concentrations across kitchen surfaces.Spice containers may be a key vehicle for cross-contamination.The thermometer safety intervention did not affect cross-contamination.The efficiency of MS2 transfer was relatively low, ranging from 0.002 to 0.07%.