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Category Archives: Food Microbiology Research
Research – Microbiological Quality and Antibiotic Resistance of Relevant Bacteria from Horsemeat
The aim of this work was to assess the microbiological safety and quality of horsemeat. A total of 19 fresh horsemeat samples were analysed. Mesophile counts were 4.89 ± 1.08 log CFU/g, and Enterobacteriaceae, Staphylococcus spp., and enterococci were only isolated from 36.84%, 21.05%, and 15.79% of the samples, respectively. Neither Staphylococcus aureus nor Escherichia coli were found in any sample. Listeria spp. and Listeria monocytogenes were detected in 31.58% and 21.05% of the samples, respectively. Campylobacter jejuni was not detected in any sample. The dominant bacteria were lactic acid bacteria. Seven different Staphylococcus spp. were identified, the most common being S. delphini, S. saprophyticus, and S. warneri. S. delphini showed resistance against mupirocin and cefoxitin. All the L. monocytogenes strains showed resistance against ampicillin, cefotaxime, and oxacillin. Multi-resistant Yersinia enterocolitica, Stenotrophomonas maltophilia, and Vagococcus. fluvialis strains were found, with resistance to 11, 7, and 8 antibiotics, respectively, causing significant concern. Therefore, specific actions should be taken to decrease the contamination of horsemeat.
Research – Berry Pomace Extracts as a Natural Washing Aid to Mitigate Enterohaemorrhagic E. coli in Fresh Produce
Abstract
Enterohemorrhagic Escherichia coli (EHEC) outbreaks have been frequently linked to the consumption of produce. Furthermore, produce grown on organic farms possess a higher risk, as the farmers avoid antibiotics and chemicals. This study sets out to evaluate the effectiveness of advanced postharvest disinfection processes using berry pomace extracts (BPEs) in reducing EHEC load in two common leafy greens, spinach and lettuce. Spinach and lettuce were inoculated with ~5 log CFU/leaf EHEC EDL-933 and then treated with three different concentrations of BPE (1, 1.5, and 2 gallic acid equivalent, GAE mg/mL) for increasing periods of time. After the wash, the bacteria were quantified. Changes in the relative expression of virulence genes and the genes involved in cell division and replication and response against stress/antibiotics were studied. We observed a significant reduction in EHEC EDL933, ranging from 0.5 to 1.6 log CFU/spinach leaf (p < 0.05) washed with BPE water. A similar trend of reduction, ranging from 0.3 to 1.3 log CFU/mL, was observed in pre-inoculated lettuce washed with BPE water. We also quantified the remaining bacterial population in the residual treatment solutions and found the survived bacterial cells (~3 log CFU/mL) were low despite repeated washing with the same solution. In addition, we evaluated the phenolic concentration in leftover BPE, which did not change significantly, even after multiple uses. Alterations in gene expression levels were observed, with downregulation ranging from 1 to 3 log folds in the genes responsible for the adhesion and virulence of EHEC EDL933 and significant upregulation of genes responsible for survival against stress. All other genes were upregulated, ranging from 2 to 7 log folds, with a dose-dependent decrease in expression. This finding shows the potential of BPE to be used for sanitation of fresh produce as a natural and sustainable approach.
Posted in Bio-Preservative, EHEC, Food Microbiology Research, Research, STEC, STEC E.coli
Research – Response of Escherichia coli to Acid Stress: Mechanisms and Applications—A Narrative Review
Abstract
Change in pH in growth conditions is the primary stress for most neutralophilic bacteria, including model microorganism Escherichia coli. However, different survival capacities under acid stress in different bacteria are ubiquitous. Research on different acid-tolerance mechanisms in microorganisms is important for the field of combating harmful gut bacteria and promoting fermentation performance of industrial strains. Therefore, this study aimed to carry out a narrative review of acid-stress response mechanism of E. coli discovered so far, including six AR systems, cell membrane protection, and macromolecular repair. In addition, the application of acid-tolerant E. coli in industry was illustrated, such as production of industrial organic acid and developing bioprocessing for industrial wastes. Identifying these aspects will open the opportunity for discussing development aspects for subsequent research of acid-tolerant mechanisms and application in E. coli.
Posted in E.coli, Food Microbiology Research, Research
France – Mackerel fillet with smoked onion – Listeria monocytogenes

Product Category
Food
Product subcategory
Fishery and aquaculture products
Product brand name
UNBRANDED
Model names or references
Mackerel fillet with smoked onion
Product identification
GTIN Date
0205686000003 Expiry date 08/25/2024
Start/End of marketing date
From 06/08/2024 to 25/08/2024
Storage temperature
Product to be kept in the refrigerator
Geographic area of sale
LA FERTE-ST-AUBIN, LANVALLAY, LA TURBALLE, ST CONTEST, ARVERT
Distributors
COOPERATIVE U
Posted in food contamination, food handler, Food Hazard, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Quality, food recall, Food Safety, Food Safety Alert, Food Safety Management, Food Safety Regulations, Food Testing, Listeria, Listeria France, Listeria monocytogenes
South Korea – Foodborne Illness on the Rise in South Korea
In 2023, South Korea experienced a significant increase in food poisoning cases compared to the previous three years during the COVID-19 pandemic. The country’s Ministry of Food and Drug Safety reported 359 cases affecting 8,789 patients, representing a 1.5-fold increase in cases and more than double the number of patients compared to the 2020 to 2022 average.
The analysis revealed a concentration of food poisoning incidents during the summer months, with 33.7% of cases occurring from July to September. Surprisingly, September saw the highest number of cases and patients, with 43 incidents affecting 1,590 individuals. July followed closely with 41 cases and 1,563 patients, while August recorded 37 cases with 977 patients.
Research – Systematic risk ranking of microbiological hazards in infant foods
Abstract
Ensuring food safety, particularly for vulnerable groups, like infants and young children, requires identifying and prioritizing potential hazards in food chains. We previously developed a web-based decision support system (DSS) to identify specific microbiological hazards (MHs) in infant and toddler foods through a structured five-step process. This study takes the framework further by introducing systematic risk ranking (RR) steps to rank MH risks with seven criteria: process survival, recontamination, growth opportunity, meal preparation, hazard-food association evidence, food consumption habits of infants and toddlers in the EU, and MH severity. Each criterion is given a semi-quantitative or quantitative score or risk value, contributing to the final MH risk calculation via three aggregation methods: semi-quantitative risk scoring, semi-quantitative risk value, and outranking multi-criteria decision analysis (MCDA). To validate the criteria and ranking approaches, we conducted a case study to rank MH risks in infant formula, compared the results of the three risk ranking methods, and additionally evaluated the ranking results against expert opinions to ensure their accuracy. The results showed strong agreement among the three methods, consistently ranking Salmonella non-Typhi and Cronobacter spp. and Shiga-toxin-producing Escherichia coli as the top MH risks in infant formulae, with minor deviations. When MHs were ranked after an initial hazard identification step, all three methods produced nearly identical MH rankings, reinforcing the reliability of the ranking steps and the selected criteria. Notably, the risk value and MCDA methods provided more informative MH rankings compared to the risk scoring method. The risk value and risk scoring methods were implemented into an online tool, called the MIcrobiological hazards risk RAnking decision support system (Mira-DSS), available at https://foodmicrobiologywur.shinyapps.io/MIcrobial_hazards_RAnking/. In conclusion, our framework enables the ranking of MH risks, facilitating intervention comparisons and resource allocations to mitigate MH risks in infant foods, with potential applicability to broader food categories.
Research – Report on the establishment of the safe shelf life of certain ready-to-eat, sliced and pre-packaged foods in the retail trade in relation to the risk of Listeria monocytogenes
Report on the establishment of the safe shelf life of certain ready-to-eat, sliced and pre-packaged foods in the retail trade in relation to the risk of Listeria monocytogenes
Abstract
The Barcelona Public Health Agency (ASPB) asked the Scientific Advisory Committee on Food Safety for an opinion on the safe shelf life of Listeria monocytogenes in certain products (cheeses, cooked meats, including pâtés, and cured meats) sliced and pre-packaged prior to retail sale.
In order to assess in which cases or under which conditions ready-to-eat foods under study may promote the growth of pathogenic microorganisms during their shelf life the methodology proposed by EFSA (2020) was used. In addition, the predictive model of growth / non-growth boundaries, based on the gamma concept approach, was applied.
To carry out this assessment, the ASPB provided a total of 90 samples (32 in 2020
and 58 in 2021) divided into 4 categories of ready-to-eat foods: cheese, cooked ham, pâté / foie and cured ham. In all cases, the food was sliced or cut into portions in retail establishments of the city of Barcelona, and packaged in different formats: vacuum-packed, in a heat-sealed or shrink-wrapped tray, or wrapped in film.
The results of the evaluation indicated that the ready-to-eat pre-packaged foods evaluated for the group of cheeses, cooked ham, pâtés and foie required the indication of “use by” date, as the handling conditions expose the product to a potential L. monocytogenes contamination and the pH and aw (water activity) characteristics associated with these products support its growth.
Considering a reasonably foreseeable scenario in relation to storage temperature
conditions in retail (2 days at 5 °C) and in a domestic refrigerator (5 days at 9.5 °C), the safe shelf life of the products that more would favor the growth of L. monocytogenes would be between 4.5 and 4.9 days (corresponding to the 5th and 10th percentile, respectively). This estimate is the result of a conservative approach that provides a margin of safety to the outcome of the evaluation.
Research – Mycotoxin control in cereals: safe guarding food
The aim of this research was to review (and where possible improve/refine
current rapid screening methods for the mycotoxin T-2 and its metabolites in
cereals for human consumption.
Researchers engaged with the relevant sector of the cereal processing industry in
Ireland and the UK, and the relevant primary production sector, to gain detailed,
valuable information.
The research conducted was designed to clarify deficits in T-2 toxin control in the
relevant processing and primary production sectors, evaluate the robustness of
current analytical detection and control methods therein, augment same if deemed
necessary, and implement workable T-2 toxin control solutions at sectoral level.
Objectives
The specific objectives of the research project were to:
• Conduct a literature review of the most up-to-date scientific and
regulatory data for T-2 toxin and its metabolites, the specific environmental conditions required for their production, and the impact of climate change on their occurrence and distribution.
• Undertake a thorough analysis of the currently available commercial rapid analytical techniques for the screening of T-2 and HT-2 toxins in cereals for direct human consumption.
• Undertake a survey of the relevant processing and primary production sectors to determine what testing they currently conduct for mycotoxins, to fully understand the shortfalls in relation to mycotoxin monitoring and control within the industry.
Conduct a survey of oats and barley (n≥100) using mass spectrometry to identify contamination levels of, not only the mycotoxins of interest, i.e., T-2 and HT-2, but also all other regulated mycotoxins including aflatoxins, deoxynivalenol, zearalenone, fumonisins and ochratoxin A.
• Perform a thorough evaluation of a selected number of rapid test kits to ascertain fitness for purpose and determine how to adapt the most robust methods for better performance. If required, undertake a training workshop on the use of the best performing rapid testing kits.
• Engage with stakeholders to discuss the implications of the findings of
the project and produce a series of conclusions and recommendations
for stakeholders on the island of Ireland.
Research – Staphylococcal Enterotoxins: Description and Importance in Food
Abstract
Staphylococcus aureus stands out as one of the most virulent pathogens in the genus Staphylococcus. This characteristic is due to its ability to produce a wide variety of staphylococcal enterotoxins (SEs) and exotoxins, which in turn can cause staphylococcal food poisoning (SFP), clinical syndromes such as skin infections, inflammation, pneumonia, and sepsis, in addition to being associated with the development of inflammation in the mammary glands of dairy cattle, which results in chronic mastitis and cell necrosis. SEs are small globular proteins that combine superantigenic and emetic activities; they are resistant to heat, low temperatures, and proteolytic enzymes and are tolerant to a wide pH range. More than 24 SE genes have been well described (SEA-SEE, SEG, SEH, SEI, SEJ, SElK, SElL, SElM, SElN, SElO, SElP, SElQ, SElR, SElS, SElT, SElU, SElV, SElW, SElX, SElY, and SElZ), being a part of different SFP outbreaks, clinical cases, and isolated animal strains. In recent years, new genes (sel26, sel27, sel28, sel31, sel32, and sel33) from SEs have been described, as well as two variants (seh-2p and ses-3p) resulting in a total of thirty-three genes from Ses, including the nine variants that are still in the process of genetic and molecular structure evaluation. SEs are encoded by genes that are located in mobile genetic elements, such as plasmids, prophages, pathogenicity islands, and the enterotoxin gene cluster (egc), and housed in the genomic island of S. aureus. Both classical SEs and SE-like toxins (SEls) share phylogenetic relationships, structure, function, and sequence homology, which are characteristics for the production of new SEs through recombination processes. Due to the epidemiological importance of SEs, their rapid assessment and detection have been crucial for food security and public health; for this reason, different methods of identification of SEs have been developed, such as liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS), molecular methods, and whole-genome sequencing; providing the diagnosis of SEs and a better understanding of the occurrence, spread, and eradication of SEs. This review provides scientific information on the enterotoxins produced by S. aureus, such as structural characteristics, genetic organization, regulatory mechanisms, superantigen activity, mechanisms of action used by SEs at the time of interaction with the immune system, methods of detection of SEs, and recent biocontrol techniques used in food.
Research – Global prevalence of staphylococcal enterotoxins in food contaminated by Staphylococcus spp.—Systematic review and meta-analysis
Abstract
This systematic review (SR) and meta-analysis integrates the results of studies on the occurrence of staphylococcal enterotoxin (SE), the knowledge related to the profile of the foods most often involved, and the types of SE found. The study followed the guidelines of the Preferred Reporting Items for SR and Meta-Analyses, and its protocol was registered on the PROSPERO platform (CRD42021258223). Primary cross-sectional studies that report the analysis of SEs in food contaminated by Staphylococcus spp. were selected. All stages of study selection and data extraction were performed by two researchers independently, and in cases of conflicts, a third researcher was consulted. To assess the risk of bias, we used the critical appraisal checklist of the Joanna Briggs Institute. A total of 3012 reports were listed initially and 217 after the search update. After removing the duplicates, 2535 studies were found combining all databases and manual searches. Thus, 38 studies were included in this SR. In the meta-analysis, group 1 (dairy products) showed a prevalence of positive samples for SE of 15.38%, group 2 (meat products) 1.78% and group 3 (other foods) 27.11%. The results showed a considerable prevalence of SE in food contaminated by Staphylococcus spp., especially in group 3, which included mixed and ready-to-eat foods. This SR contributes to the study of the epidemiological profile and highlights the importance of adopting more effective prevention measures and policies aimed at improving public health.
