Category Archives: Food Microbiology Research

Research – Salmonella infections in Denmark from 2013–2022 with focus on serotype distribution, invasiveness, age, sex, and travel exposition

Posted on April 7, 2024 by | Leave a comment

Springer Link

Purpose

To analyze the nationwide incidence of Salmonella infections in Denmark from 2013 to 2022.

Methods

Confirmed cases of Salmonella enterica subsp. enterica were examined using the National Register of Enteric Pathogens during 2013–2022. Proportions, incidence rates (IR), relative risk (RR), and 95% confidence intervals (CI) were calculated to assess differences in serotypes, invasiveness, age, sex, and travel exposure.

Results

We identified 9,944 Danish Salmonella enterica subsp. enterica cases, with an average annual incidence rate of 16.9 per 100,000 inhabitants, declining during the COVID-19 pandemic. Typhoidal cases totaled 206, with an average annual IR of 0.35 per 100,000 inhabitants. Enteric fever patients had a median age of 24 years (IQR:17–36). Leading non-typhoid Salmonella (NTS) serotypes were S. Enteritidis (26.4%), monophasic S. Typhimurium (16.5%), and S. Typhimurium (13.5%). Median age for NTS cases was 42 (IQR: 18–62), with even sex distribution, and a third reported travel prior to onset of disease. The overall percentage of invasive NTS (iNTS) infection was 8.1% (CI: 7.6–8.7). Eleven serotypes were associated with higher invasiveness, with S. Dublin and S. Panama having the highest invasiveness with age and sex-adjusted RR of 7.31 (CI: 6.35–8.43) and 5.42 (CI: 3.42–8.60), respectively, compared to all other NTS serotypes. Increased age was associated with higher RR for iNTS infection.

Conclusion

During the decade, there was a limited number of typhoidal cases. The dominant NTS serotypes were S. Enteritidis and monophasic S. Typhimurium, whereas S. Dublin and S. Panama exhibited the highest invasive potential.

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Posted in food bourne outbreak, Food Illness, Food Microbiology Research, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Illness, outbreak, Research, Salmonella

Research – Susceptibility of Salmonella enterica Typhimurium dry surface biofilms to disinfection

Posted on April 6, 2024 by | Leave a comment

Wiley Online

Abstract

In food preparation and manufacturing environments, surfaces contaminated with Salmonella can lead to outbreaks of Salmonellosis. We hypothesise that Salmonella resides on dry surfaces in a biofilm form leading to potential environmental persistence and transfer following contact. This is the first study reporting that Salmonella Typhimurium can form dry surface biofilm (DSB). Six disinfectants commonly used in the food industry were evaluated for their efficacy against the DSB. The two most efficacious formulations reduced bacterial viability in DSB by >99.99% when combined with mechanical removal (5 sec wiping; 300 g weight). Five out of six formulations significantly reduced bacterial transfer when combined with wiping. Complete eradication of Salmonella Typhimurium DSB was challenging, and mechanical removal was essential to produce a >99.99% reduction in bacterial viability within DSB. This study highlights a potential mode of survival of Salmonella Typhimurium on food-contact surfaces and DSB challenges for disinfection.

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Posted in Biofilm, Food Microbiology Research, Research, Salmonella

Research – Differences in Biofilm Formation of Listeria monocytogenes and Their Effects on Virulence and Drug Resistance of Different Strains

Posted on April 6, 2024 by | Leave a comment

MDPI

Abstract

Listeria monocytogenes is recognized as one of the primary pathogens responsible for foodborne illnesses. The ability of L. monocytogenes to form biofilms notably increases its resistance to antibiotics such as ampicillin and tetracycline, making it exceedingly difficult to eradicate. Residual bacteria within the processing environment can contaminate food products, thereby posing a significant risk to public health. In this study, we used crystal violet staining to assess the biofilm-forming capacity of seven L. monocytogenes strains and identified ATCC 19112 as the strain with the most potent biofilm-forming. Subsequent fluorescence microscopy observations revealed that the biofilm-forming capacity was markedly enhanced after two days of culture. Then, we investigated into the factors contributing to biofilm formation and demonstrated that strains with more robust extracellular polymer secretion and self-agglutination capabilities exhibited a more pronounced ability to form biofilms. No significant correlation was found between surface hydrophobicity and biofilm formation capability. In addition, we found that after biofilm formation, the adhesion and invasion of cells were enhanced and drug resistance increased. Therefore, we hypothesized that the formation of biofilm makes L. monocytogenes more virulent and more difficult to remove by antibiotics. Lastly, utilizing RT-PCR, we detected the expression levels of genes associated with biofilm formation, including those involved in quorum sensing (QS), flagellar synthesis, and extracellular polymer production. These genes were significantly upregulated after biofilm formation. These findings underscore the critical relationship between extracellular polymers, self-agglutination abilities, and biofilm formation. In conclusion, the establishment of biofilms not only enhances L. monocytogenes’ capacity for cell invasion and adhesion but also significantly increases its resistance to drugs, presenting a substantial threat to food safety.

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Posted in Biofilm, Food Microbiology Research, Food Pathogen, Listeria, Listeria monocytogenes, Pathogen, pathogenic, Research

Research – Scientists further our understanding of how a foodborne bacterium can survive in food preparation environments

Posted on April 4, 2024 by | Leave a comment

Science Daily

Scientists from the Quadram Institute and UK Health Security Agency have discovered that bacterial populations remain stable on factory floor despite cleaning efforts in ready-to-eat food production facilities.

In 2019, six people died from a listeria outbreak caused by contaminated ready-to-eat foods served in a number of hospitals across the UK. In light of this, scientists are now performing vital research which helps to understand how these pathogens can persist in ready-to-eat food preparation environments.

The results showed that the populations of bacteria that coexist with L. monocytogenes were stable over time and have adapted to the conditions on the factory floor, including food safety controls. Maria Diaz from the Quadram Institute and lead of the study explains, “as L. monocytogenes is supported by a stable community of other bacteria, we may now need to develop new strategies to alter the whole bacterial population to effectively eliminate the pathogen.”

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Posted in Food Microbiology Research, Listeria, Listeria monocytogenes, Research

Research – Inhibition and eradication of Listeria monocytogenes biofilm using the combined treatment with nisin and sesamol

Posted on April 4, 2024 by | Leave a comment

Science Direct

Abstract

Listeria monocytogenes can form biofilms, which enables it to persist in the food industry and poses a significant threat to food safety. The combination of nisin (NS) and sesamol (SE) has been found to inhibit the proliferation of L. monocytogenes. The objective of this study is to evaluate the effects of the combined use of NS and SE on the biofilm formation of L. monocytogenes and investigate the potential underlying mechanisms. The results showed that the combination of NS and SE completely inhibited the biofilm formation of both strains on the stainless steel sheet within 48 h. The existing L. monocytogenes biofilm on the stainless steel sheet was completely removed within 4 h after the combined treatment of NS and SE. Compared with individual treatment, the combined use of NS and SE resulted in a more significant downregulation in gene expression of fbpA, which is associated with L. monocytogenes biofilm formation. The findings suggest that the combined strategy of NS and SE in food processing has greater potential to control the formation of L. monocytogenes biofilms and eliminate existing ones, compared with using NS or SE alone.

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Posted in Biofilm, Food Microbiology Research, Listeria, Listeria monocytogenes, Nisin, Research

Research – Combined antibacterial effect of Origanum essential oils and antibiotics against multi-resistant foodborne Salmonella isolated from poultry and shellfish in Morocco

Posted on April 3, 2024 by | Leave a comment

Wiley Online

Abstract

The present study aims to assess the antibacterial activity of endemic Moroccan Origanum essential oils (Origanum elongatum and Origanum compactum) alone and in association with antibiotics against multidrug resistant foodborne Salmonella. The well diffusion and microdilution procedures were used to evaluate the antibacterial activity. The synergistic interactions between antibiotics and EOs were determined using the checkerboard assay. The results of the antibacterial activity indicated that all of Salmonella serovars isolates that were examined were highly inhibited by EOs. This effect was confirmed by the microdilution technique, where 0.125% was noted as the smallest MIC value. Based on the obtained MBC values, O. elongatum shown a bactericidal action against the tested strains as indicated by the acquired MBC values. While O. compactum showed this effect against different serovars of Salmonella isolates. Origanum EOs could be employed as an alternative to the former protocols against resistant infectious diseases.

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Posted in Antibacterial, Food Microbiology Research, Research, Salmonella

Hong Kong – Oyster Food Safety Booklet

Posted on April 3, 2024 by | Leave a comment

CFS

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Posted in Center for Food Safety, E.coli, Food Microbiology Research, Food Safety, Food Safety Management, Food Safety Regulations, food safety training, raw oysters, Research

USA – Fratelli Beretta Charcuterie linked to 104 Salmonella Illnesses

Posted on April 2, 2024 by | Leave a comment

Food Poison Journal

A total of 104 people infected with the outbreak strain of Salmonella were reported from 33 states. Illnesses started on dates ranging from November 20, 2023, to February 10, 2024. Of 92 people with information available, 27 were hospitalized. No deaths were reported.

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Posted in food bourne outbreak, Food Illness, Food Microbiology Research, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Illness, outbreak, Research, Salmonella

Italy – Horse frays 100 grams – Listeria monocytogenes

Posted on April 2, 2024 by | Leave a comment

Salute

Brand : Masina Dal 1929

Name : Horse frays 100 grams

Reason for reporting : Recall due to microbiological risk

Publication date : 28 March 2024

Documentation

Documentation

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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, Listeria, Listeria monocytogenes

Research- WGS Responsible for Quick Detection of Salmonella Outbreak

Posted on April 1, 2024 by | Leave a comment

IDSE

The use of whole genome sequencing (WGS)-based surveillance and rapid epidemiological intervention allowed public health experts to quickly link a Salmonella enterica serovar Typhimurium outbreak to cantaloupes grown in the United States.

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Posted in food bourne outbreak, Food Illness, Food Microbiology Research, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Illness, outbreak, Research, Salmonella, Salmonella Cantaloupes, WGS, Whole Genomic Sequencing