Factors that predict Listeria prevalence in distribution centers handling fresh produce.

Listeria species prevalence has been investigated at nearly all stages of the fresh produce supply chain; however, it has not been examined in transportation and distribution center (DC) related environments. Between December 2019 and March 2021, 18 DCs handling fresh produce were environmentally sampled for Listeria. Swab samples were collected from a variety of surfaces (e.g., floors, pallets, forklifts) in several areas of each DC (e.g., cold storage, shipping and receiving docks). Impaction air samples, relative humidity, and temperature data were also collected. While no Listeria spp. were isolated from air samples (n = 170), they were isolated from 49 of 982 (ca. 5%) environmental samples. The proportion of Listeria spp. positive samples varied significantly across individual DCs (P < 0.01). Several facility characteristics were significantly associated with a Listeria spp. positive sample, such as zone, sampling site dryness, and cleaning regimen. A random forest model (sensitivity: 0.786, specificity: 0.874) identified geographical location and general sampling location (e.g., cold storage rooms, shipping docks) as the two most important variables associated with Listeria spp. detection. This study identified likely harborage sites (e.g., floors, cleaning equipment) of Listeria spp. in DCs across the US and emphasized the importance of sanitation operations in Listeria-prone areas.

A quasimetagenomics method for concerted detection and subtyping of Salmonella enterica and E. coli O157:H7 from romaine lettuce.

Quasimetagenomics refers to the sequencing of a modified food microbiome to facilitate combined detection and subtyping of targeted pathogens in a single workflow. Through quasimetagenomic sequencing, pathogens are detected and subtyped in a shortened time frame compared to traditional culture enrichment and whole genome sequencing-based analyses. While this method was previously used to detect and subtype Salmonella enterica from chicken, iceberg lettuce, and black pepper, it has not been applied to investigate multiple pathogens in one workflow. A quasimetagenomic method to concertedly detect and subtype Salmonella enterica and Escherichia coli O157:H7 from artificially contaminated romaine lettuce in a single workflow was developed. All quasimetagenomic samples with initial target pathogen inoculum levels of ~1 CFU/g were detected and serotyped after co-enrichment of the two pathogens for 12 h. Single nucleotide polymorphism typing was achievable for some initial pathogen inoculum levels as low as ~0.1 CFU/g. Our results suggest that this method can be used for concerted detection and subtyping of multiple bacterial pathogens from romaine lettuce even at low contamination levels.

16S microbiome analysis of microbial communities in distribution centers handling fresh produce.

Little is known about the microbial communities found in distribution centers (DCs), especially in those storing and handling food. As many foodborne bacteria are known to establish residence in food facilities, it is reasonable to assume that DCs handling foods are also susceptible to pathogen colonization. To investigate the microbial communities within DCs, 16S amplicon sequencing was completed on 317 environmental surface sponge swabs collected in DCs (n = 18) across the United States. An additional 317 swabs were collected in parallel to determine if any viable Listeria species were also present at each sampling site. There were significant differences in median diversity measures (observed, Shannon, and Chao1) across individual DCs, and top genera across all reads were Carnobacterium_A, Psychrobacter, Pseudomonas_E, Leaf454, and Staphylococcus based on taxonomic classifications using the Genome Taxonomy Database. Of the 39 16S samples containing Listeria ASVs, four of these samples had corresponding Listeria positive microbiological samples. Data indicated a predominance of ASVs identified as cold-tolerant bacteria in environmental samples collected in DCs. Differential abundance analysis identified Carnobacterium_A, Psychrobacter, and Pseudomonas_E present at a significantly greater abundance in Listeria positive microbiological compared to those negative for Listeria. Additionally, microbiome composition varied significantly across groupings within variables (e.g., DC, season, general sampling location).

A Systematic Review of Listeria Species and Listeria monocytogenes Prevalence, Persistence, and Diversity throughout the Fresh Produce Supply Chain.

Listeria monocytogenes is an increasing food safety concern throughout the produce supply chain as it has been linked to produce associated outbreaks and recalls. To our knowledge, this is the first systematic literature review to investigate Listeria species and L. monocytogenes prevalence, persistence, and diversity at each stage along the supply chain. This review identified 64 articles of 4863 candidate articles obtained from four Boolean search queries in six databases. Included studies examined naturally detected/isolated Listeria species and L. monocytogenes in fresh produce-related environments, and/or from past fresh produce associated outbreaks or from produce directly. Listeria species and L. monocytogenes were detected in each stage of the fresh produce supply chain. The greatest prevalence of Listeria species was observed in natural environments and outdoor production, with prevalence generally decreasing with each progression of the supply chain (e.g., packinghouse to distribution to retail). L. monocytogenes prevalence ranged from 61.1% to not detected (0.00%) across the entire supply chain for included studies. Listeria persistence and diversity were also investigated more in natural, production, and processing environments, compared to other supply chain environments (e.g., retail). Data gaps were identified for future produce safety research, for example, in the transportation and distribution center environment.

Assessing the Impact of a Preclinical Immersion on Nurse Practitioner Student Confidence for the Initial Clinical Experience.

BACKGROUND: It is important for faculty to prepare nurse practitioner students for their first clinical experiences to ensure student success. PURPOSE: The purpose of this project was to implement a preclinical immersion and determine student perceptions about this experience. METHODS: A half-day preclinical immersion was instituted at the beginning of the family nurse practitioner students' first clinical course. Demographic information and survey data were obtained before the preclinical immersion experience, after completion of the immersion experience, and during the last 2 weeks of the first clinical course. RESULTS: Students' ratings of their clinical skills and knowledge improved during the duration of the semester for 5 of the 7 items. Directed content analysis revealed 3 themes: understanding of clinical expectations, face-to-face interactions with faculty, and cognitive/emotional clinical perceptions. CONCLUSION: The use of preclinical immersion experiences may both practically and emotionally prepare students for graduate nursing clinical experiences.

Biocides and Novel Antimicrobial Agents for the Mitigation of Coronaviruses.

In December, 2019, a highly infectious and rapidly spreading new pneumonia of unknown cause was reported to the Chinese WHO Country Office. A cluster of these cases had appeared in Wuhan, a city in the Hubei Province of China. These infections were found to be caused by a new coronavirus which was given the name "2019 novel coronavirus" (2019-nCoV). It was later renamed "severe acute respiratory syndrome coronavirus 2," or SARS-CoV-2 by the International Committee on Taxonomy of Viruses on February 11, 2020. It was named SARS-CoV-2 due to its close genetic similarity to the coronavirus which caused the SARS outbreak in 2002 (SARS-CoV-1). The aim of this review is to provide information, primarily to the food industry, regarding a range of biocides effective in eliminating or reducing the presence of coronaviruses from fomites, skin, oral/nasal mucosa, air, and food contact surfaces. As several EPA approved sanitizers against SARS-CoV-2 are commonly used by food processors, these compounds are primarily discussed as much of the industry already has them on site and is familiar with their application and use. Specifically, we focused on the effects of alcohols, povidone iodine, quaternary ammonium compounds, hydrogen peroxide, sodium hypochlorite (NaOCl), peroxyacetic acid (PAA), chlorine dioxide, ozone, ultraviolet light, metals, and plant-based antimicrobials. This review highlights the differences in the resistance or susceptibility of different strains of coronaviruses, or similar viruses, to these antimicrobial agents.

Quasi-metagenomic Analysis of Salmonella from Food and Environmental Samples.

Quasi-metagenomics sequencing refers to the sequencing-based analysis of modified microbiomes of food and environmental samples. In this protocol, microbiome modification is designed to concentrate genomic DNA of a target foodborne pathogen contaminant to facilitate the detection and subtyping of the pathogen in a single workflow. Here, we explain and demonstrate the sample preparation steps for the quasi-metagenomics analysis of Salmonella enterica from representative food and environmental samples including alfalfa sprouts, ground black pepper, ground beef, chicken breast and environmental swabs. Samples are first subjected to the culture enrichment of Salmonella for a shortened and adjustable duration (4-24 h). Salmonella cells are then selectively captured from the enrichment culture by immunomagnetic separation (IMS). Finally, multiple displacement amplification (MDA) is performed to amplify DNA from IMS-captured cells. The DNA output of this protocol can be sequenced by high throughput sequencing platforms. An optional quantitative PCR analysis can be performed to replace sequencing for Salmonella detection or assess the concentration of Salmonella DNA before sequencing.