Author Archives: KSW

Research – Verification of a Rapid Analytical Method for the Qualitative Detection of Listeria spp. and Listeria monocytogenes by a Real-Time PCR Assay according to EN UNI ISO 16140-3:2021

Posted on February 9, 2024 | Leave a comment

MDPI

Abstract

Microbial contamination and foodborne infections are a significant global public health concern. For this reason, the detection, monitoring, and characterization of pathogens represent a significant challenge in quality control settings. Standard approaches, such as culture methods and biochemical tests, are known to be very time-consuming and intensive. Conversely, molecular technologies based on the genomic identification of bacteria are quick and low-cost. Listeria monocytogenes is an opportunistic pathogen and a major concern especially in food industries. It is important to understand and implement multiple quality control measures to control Listeria infection risk and prevent the contamination of products. Standardized detection and confirmation tests such as the API Listeria test, MALDI-TOF MS, and PCR analysis are available. The aim of our work is to provide a specific molecular method, designed according to the EN UNI ISO 16140-3:2021, for the specific detection, monitoring, and characterization of Listeria spp. and Listeria monocytogenes contamination. The verification of this new rapid approach by real-time PCR (qPCR) overcomes the limitations of culture-based techniques, meeting all the verification criteria required by ISO guidelines, including implementation and item confirmation. This system offers a powerful approach to the real-time assessment of food safety, useful for industry self-monitoring and regulatory inspection.

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Posted in Food Microbiology Research, ISO Standards, Listeria, Listeria monocytogenes, PCR, Research

RASFF Alert- French Oysters – Norovirus – Frozen Giant American Blueberries

Posted on February 9, 2024 | Leave a comment

RASFF

Norovirus in oysters from France in Belgium

RASFF

Norovirus in Oysters from France in Italy, Singapore, Switzerland, Kazakhstan

RASFF

Norovirus in Frozen Giant American Blueberries from Poland in Italy and Malta

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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 Testing, Food Pathogen, Food Quality, food recall, Food Safety, Food Safety Alert, Food Safety Management, Food Safety Regulations, Food Testing, Food Virus, Norovirus, Norovirus French Oysters, Norovirus Oysters, RASFF

RASFF Alert- E.coli – Live Clams

Posted on February 9, 2024 | Leave a comment

RASFF

E.coli in live clams from Italy in Spain

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Posted in E.coli, food contamination, food handler, Food Hazard, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Pathogen, Food Quality, food recall, Food Safety, Food Safety Alert, Food Safety Management, Food Safety Regulations, Food Testing, RASFF

RASFF Alerts – STEC E.coli – Sucuk Salami – Psyllium Fibre

Posted on February 9, 2024 | Leave a comment

RASFF

Presence of E. Coli VTEC O103:H2 in 99% psyllium fibre from India in Italy

RASFF

STEC in sucuk salami from Poland in Germany and Denmark

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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 Testing, Food Pathogen, Food Quality, food recall, Food Safety, Food Safety Alert, Food Safety Management, Food Safety Regulations, Food Testing, STEC, STEC E.coli

RASFF Alert- Animal Feed – Aflatoxin – Millet Grains

Posted on February 9, 2024 | Leave a comment

RASFF

Aflatoxin B1 in millet grains from India in Spain

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Posted in Aflatoxin, Aflatoxin B1, Animal Feed, Animal Feed Aflatoxin, Animal Feed Mould Toxin, Animal Feed Mould/Mold, Animal Feed Recall, Animal Feed Testing, Aspergillus Toxin, Food Toxin, Mold Toxin, Mould Toxin, Mycotoxin, RASFF

RASFF Alerts – Animal Feed – Salmonella – Organic Sunflower Cake – Pet Food

Posted on February 9, 2024 | Leave a comment

RASFF

Salmonella spp. in organic sunflower cake from Germany in Austria

RASFF

Salmonella and Enterobacteriaceae in pet food from Turkey in Spain

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Posted in Animal Feed Salmonella, Animal Feed Testing, Pet Food, Pet Food Enterobacteriaceae, Pet Food Recall, Pet Food Salmonella, Pet Food Testing, RASFF, Uncategorized

Research – Comparative Analysis of Growth, Survival, and Virulence Characteristics of Listeria monocytogenes Isolated from Imported Meat

Posted on February 9, 2024 | Leave a comment

MDPI

Listeria monocytogenes is an important foodborne pathogen with worldwide prevalence. Understanding the variability in the potential pathogenicity among strains of different subtypes is crucial for risk assessment. In this study, the growth, survival, and virulence characteristics of 16 L. monocytogenes strains isolated from imported meat in China (2018–2020) were investigated. The maximum specific growth rate (μmax) and lag phase (λ) were evaluated using the time-to-detection (TTD) method and the Baranyi model at different temperatures (25, 30, and 37 °C). Survival characteristics were determined by D-values and population reduction after exposure to heat (60, 62.5, and 65 °C) and acid (HCl, pH = 2.5, 3.5, and 4.5). The potential virulence was evaluated via adhesion and invasion to Caco-2 cells, motility, and lethality to Galleria mellonella. The potential pathogenicity was compared among strains of different lineages and subtypes. The results indicate that the lineage I strains exhibited a higher growth rate than the lineage II strains at three growth temperatures, particularly serotype 4b within lineage I. At all temperatures tested, serotypes 1/2a and 1/2b consistently demonstrated higher heat resistance than the other subtypes. No significant differences in the log reduction were observed between the lineage I and lineage II strains at pH 2.5, 3.5, and 4.5. However, the serotype 1/2c strains exhibited significantly low acid resistance at pH 2.5. In terms of virulence, the lineage I strains outperformed the lineage II strains. The invasion rate to Caco-2 cells and lethality to G. mellonella exhibited by the serotype 4b strains were higher than those observed in the other serotypes. This study provides meaningful insights into the growth, survival, and virulence of L. monocytogenes, offering valuable information for understanding the correlation between the pathogenicity and subtypes of L. monocytogenes.

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

Research – Cronobacter sakazakii

Posted on February 8, 2024 | Leave a comment

ACSA

Cronobacter sakazakii  is a   gram-negative, motile, non-spore-forming, facultative anaerobic, bacillary-shaped, oxidase-negative, catalase-positive bacterium . Due to its ability to form biofilms and its resistance to desiccation, it can be found widely in soil, water, plants and animals, being able to grow in a wide range of temperatures (6°C-47°C).

Cronobacter sakazakii  infection  is uncommon worldwide, but presents a high proportion of cases with neurological complications and death. The infection causes diarrheal enteritis, which often turns bloody and, in some cases, can be complicated by meningitis that leaves neurological sequelae or ends in the death of the infected baby.

The organism has been isolated from various foods of vegetable or animal origin, both dehydrated, smoked, frozen, etc. C. sakazakii  is an occasional contaminant of different foods such as cereals, porridges, dehydrated for special diets, foods for medical uses, and powdered infant formulas, being able to persist in these foods for at least 2 years due to their ability to withstand environments dry It is also necessary to consider powder preparations intended for elderly people and those intended for special medical uses given the special vulnerability of this population group.

Powder formulas

Powdered formulas are not sterile and, although they are heat treated during manufacture and conform to established microbiological criteria, they may occasionally contain low concentrations of microorganisms, including pathogens such as Cronobacter sakazakii and Salmonella enterica.

During manufacturing, microorganisms can be introduced into the powder preparations through the ingredients added in the dry mixing operations or from the environment during the drying or packaging stage. Also, powdered formulas can be contaminated by improper preparation at home.

These microorganisms are not able to multiply in dry powder preparations, but they can survive there for long periods of time, even longer than a year. Instead, the reconstituted preparation offers an ideal environment for them to proliferate.

The large-scale production and distribution of these products and the low number of infections in nursing infants indicate that the products are generally safe.

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Posted in Cronobacter sakazakii, Food Microbiology Research, Research

UK – Listeriosis in England and Wales: summary for 2022

Posted on February 8, 2024 | Leave a comment

UKHSA

Main points for 2022

This report summarises the number, demographics and clinical outcomes of confirmed cases of listeriosis from England and Wales in 2022. The main points are:

  • in 2022, 167 cases of listeriosis were reported from England and Wales which is 6.4% increase compared to the previous 5 years median
  • incidence rates of listeriosis were highest in people aged 80 years and over
  • overall, the incidence of listeriosis was greater in men than women, with the exception of higher incidence in women for the age groups 20 to 29, 30 to 39 and 70 to 79 years
  • pregnancy associated infections accounted for 14.4% of all reported cases and 28.6% of the pregnancy associated cases (where known) resulted in still birth or miscarriage
  • among non-pregnancy associated cases of listeriosis, death was reported for 33 cases (23.1%), of whom 18 (55%, or 12.6% of all non-pregnancy associated cases) were known to have listeriosis recorded as a cause of death on the death certificate
  • mortality amongst non-pregnancy associated cases was lower compared to the years preceding the COVID-19 pandemic (2015 to 2019), with a case fatality rate of 23.1% compared to a median of 39.2%
  • incidence of listeriosis varied geographically, with the lowest incidence in the West Midlands (0.17 per 100,000 population) and the highest in London (0.43 cases per 100,000 population)
  • there were 4 listeriosis outbreaks investigated in England and Wales in 2022, including a national outbreak associated with smoked fish

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

Sweden relaxes advice for groups at risk from Listeria

Posted on February 8, 2024 | Leave a comment

Food Safety News

Advice around Listeria in sliced fermented sausages and vegetarian sandwich toppings for vulnerable people in Sweden has been changed.

The Swedish Food Agency (Livsmedelsverket) has updated advice for individuals belonging to one of the risk groups for listeriosis. This includes pregnant women, elderly people, and those with weakened immune systems.

The new guidance is that people in at-risk groups may eat sliced fermented sausages, such as smoked mid-west and salami, until their use-by date. This applies as long as products are stored according to the manufacturer’s instructions. Previously, it was advised that such individuals should only eat these products within a week of the packaging date.

A risk assessment found that Listeria multiplied slowly or not at all in fermented sausages at 4 degrees C (39.2 degrees F) and 8 degrees C (46.4 degrees F). This is because such products have a low pH and low water activity.

Revised advice also states that people in risk groups may consume vegetarian sandwich toppings intended to be eaten cold until the use-by date. The change is hoped to lead to less food waste and increase the options for vulnerable consumers.

A risk assessment showed that Listeria cannot multiply in most of these toppings at 4 or 8 degrees C. This is because they have a low pH and often contain preservatives, such as lactate, nitrite, or sorbate

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Posted in Listeria, Listeria monocytogenes, Microbiological Risk Assessment, Microbiology Risk