Category Archives: Research

Research – Nisin Inhibition of Gram-Negative Bacteria

MDPI

Abstract

Aims: This study investigates the activity of the broad-spectrum bacteriocin nisin against a large panel of Gram-negative bacterial isolates, including relevant plant, animal, and human pathogens. The aim is to generate supportive evidence towards the use/inclusion of bacteriocin-based therapeutics and open avenues for their continued development.
Methods and Results: Nisin inhibitory activity was screened against a panel of 575 strains of Gram-negative bacteria, encompassing 17 genera. Nisin inhibition was observed in 309 out of 575 strains, challenging the prevailing belief that nisin lacks effectiveness against Gram-negative bacteria. The genera AcinetobacterHelicobacterErwinia, and Xanthomonas exhibited particularly high nisin sensitivity.
Conclusions: The findings of this study highlight the promising potential of nisin as a therapeutic agent for several key Gram-negative plant, animal, and human pathogens. These results challenge the prevailing notion that nisin is less effective or ineffective against Gram-negative pathogens when compared to Gram-positive pathogens and support future pursuits of nisin as a complementary therapy to existing antibiotics.
Significance and Impact of Study: This research supports further exploration of nisin as a promising therapeutic agent for numerous human, animal, and plant health applications, offering a complementary tool for infection control in the face of multidrug-resistant bacteria.

Research -Investigation of outbreak of multidrug-resistant Salmonella shows link to pet treats

Food Safety News

A new study investigating a multistate outbreak of multidrug-resistant Salmonella infections linked to pig ear pet treats highlights the interconnectedness of human health and pet ownership, emphasizing the need for stringent surveillance of pet food products.

The study was funded by the Food and Drug Administration’s Animal Feed Regulatory Program Standards and the FDA’s Veterinary Laboratory Investigation and Response Network (Vet-LIRN).

From June 2015 to Sept. 2019, 154 human cases of Salmonella infection were reported across 34 states. The investigation identified seven Salmonella serotypes genetically related to samples from pig ear pet treats. Whole genome sequencing (WGS) of isolates was used to predict antimicrobial resistance. Notably, 107 of 122 patients interviewed reported dog contact, and 65 of 97 reported contact with pig ear pet treats. Salmonella was isolated from 137 pig ear treats, including imports from Argentina, Brazil, and Colombia, and from four dogs. WGS predicted that 77 percent of human isolates and 43 percent of pig ear treat isolates were resistant to three or more antimicrobial classes.

Research – Risk Assessment of Microbiological and Chemical Hazards in Foods

MDPI

Food safety constitutes a critical regulatory and quality standard that must be fulfilled by food manufacturers throughout all phases of food production. Ingestion of food presents various risks, with chemical and biological contaminants playing a pivotal role in threatening food hygiene and safety. Therefore, continuous research and improved low-cost detection methods are essential for mitigating these risks and enhancing food safety [1,2]. Main chemical hazards are associated with the presence of endocrine disruptors, heavy metals, and neo-formed chemicals. In contrast, biological hazards stem primarily from consuming food tainted with pathogenic microorganisms. This Special Issue dealt with recent research in the domains of food hygiene and safety, addressing both chemical and biological hazards. It focused particularly on the occurrence of food xenobiotics, including mycotoxins, phthalate esters, process contaminants, and potentially toxic elements, as well as microplastics (MPs), an emerging contaminant halfway between chemical and physical risks, which has drawn significant attention due to its widespread environmental presence and potential health risks. Additionally, biological hazards and innovative detection methods in food products were thoroughly addressed. A central theme of this collection is the contamination of food by potentially toxic elements (PTEs) such as heavy metals, which could be harmful to living organisms and ecosystems, even at low concentrations [3]. Ghidini et al. (contribution 1) investigated the occurrence of PTEs in the muscle and liver of Italian heavy pigs, highlighting the potential health risks associated with dietary exposure among children. The combined consumption of pig liver and muscle could approach the tolerable weekly intake limits for Cd, Fe, and Zn, indicating potential long-term detrimental effects. Likewise, Bacchi et al. (contribution 2) report concerns about toxic metals in East Asian bullfrog legs from Vietnam and Thailand, revealing high levels of As with no significant differences between production areas. indicating potential carcinogenic and non-carcinogenic risks for consumers. This study underscores the role of arsenic-contaminated water as a significant source of As in these organisms. Mycotoxins are a major cause of food losses and represent a recurring food safety challenge [4]. The occurrence of mycotoxins in spices was another critical topic covered in this Special Issue. Nordin et al. (contribution 3) found that spices commonly used in Malaysian cuisine are susceptible to fungal contamination, with coriander seeds (ground) and black pepper (whole) showing the highest levels of fungal presence. Mycotoxigenic fungi such as A. flavus and A. niger were frequently isolated, indicating a potential risk of mycotoxin exposure for consumers. Further exploring the field of xenobiotics, contaminants from food processing are another crucial theme. Chemical contaminants in food processing can arise from various sources, i.e., high temperatures and certain cooking methods can generate harmful substances such as acrylamide, chloropropanols, and furan [5]. Additionally, contaminants may leach from packaging materials into the food during storage [6], and this aspect has also been investigated in this issue. Pekmezci and Basaran (contribution 4) discuss the implications of heat-treatment contaminants in Turkish diets. This study retrospectively analyzed the 10-year dietary habits of cancer patients, finding significant relationships between dietary heat treatment, contaminant risk scores, and cancer types. Red meat consumption was associated with the highest risk score. Another area of concern is the presence of phthalate esters in coffee. Phthalates are present in various industrial and consumer products, especially plastics. Since they are not chemically bonded to the plastic, they can leach out into the environment, leading to human exposure [7]. Velotto et al. (contribution 5) address the occurrence and risk assessment of phthalate esters in coffee, drawing attention to endocrine disruptors in a widely consumed beverage. This communication deals with the concentration of bis(2-ethylhexyl)phthalate (DEHP) and di-butyl phthalate (DBP) in coffee powder and beverages to ascertain their migration from various packaging and during different brewing methods. While no significant differences were found in phthalate levels among different packaging types, higher DEHP levels were observed in beverages extracted by professional espresso machines compared to Moka pots and home espresso machines.
Turning now to the field of foodborne pathogens, this Special Issue includes three contributions that address the challenges posed by pathogenic bacteria and nematodes. Li et al. (contribution 6) introduce a multiplex PCR system for detecting foodborne pathogens in seafood, offering a promising tool for enhancing food safety. The system described in this study shows effective detection capabilities, confirming its suitability for rapid contamination detection in these foods. Foodborne pathogens and preservation techniques were also examined. Abad et al. (contribution 7) evaluate the efficacy of pulsed electric fields (PEF) in inactivating Anisakis larvae in hake meat. The results indicated that PEF treatment is able to inactivate almost 100% of Anisakis larvae while minimally affecting the quality of hake meat compared to traditional freezing methods, which are commonly employed to mitigate Anisakis-related risk, also taking into account that Anisakis larvae can survive freezing and remain pathogenic, which may explain why some patients develop symptoms after consuming infested frozen fish [8,9]. Ji et al. (contribution 8) evaluated the effects of various organic acids and their combinations on the cell barrier and biofilm of E. coli. The findings described in this study highlight the potential for optimizing organic acid combinations for antimicrobial applications in the food industry. This comprehensive Special Issue also includes two intriguing reviews that enhance the contribution to the huge amount of food safety challenges posed by both traditional and emerging contaminants. Microplastics (MPs) in the food chain is a global issue highlighted by Borriello et al. (contribution 9), who examine human exposure to MPs through environmental and dietary sources, underscoring the widespread nature of this challenging concern. This narrative review aims to summarize MPs characteristics, sources, transport pathways, and their ecological and health impacts, identifying human exposure routes. The latter review by Başaran and Çuvalcı (contribution 10) systematically examined sixty-three articles published between January 2002 and April 2022 on the association between dietary acrylamide exposure and cancer risk. While some studies suggested a positive relationship between acrylamide exposure and cancer in various systems and organs, many others found no such link. This paves the way for further research with larger sample sizes and a broader range of foods to provide more reliable results and to advise future health policies. To conclude the interesting collection of articles presented in this Special Issue, an exciting insight into the risk assessment related to the potential consumption of a food industry by-product has also been evaluated, shedding new light on the potentials and challenges of turning waste into a resource. The study by Nolasco et al. (contribution 11) evaluates the safety of coffee silverskin (CS), a by-product of coffee roasting, for its potential use as a food ingredient. The deterministic risk assessment indicated no significant non-carcinogenic or carcinogenic risks related to CS consumption, supporting its potential safe use in functional foods [10].
In summary, this Special Issue not only offers a platform for sharing the latest research in food hygiene and safety but also encourages researchers, policymakers, and industry stakeholders to continue their collaborative efforts in addressing foodborne risks. The variety of topics covered sheds new light on the complexity of ensuring food safety in the modern world and ultimately inspires further investigation and innovation in the pursuit of safeguarding public health and ensuring the integrity of our food systems.

Research – Minced Beef Identified as Likely Source of Deadly 2023 E. Coli Outbreak in UK

Food Poisoning News

A severe outbreak of E. coli that swept across the United Kingdom in the summer of 2023, resulting in one death and dozens of severe illnesses, has now been traced back to a probable source – minced beef products.

The outbreak, according to a recent article in The Sun, which was initially detected by the UK Health Security Agency’s (UKHSA) surveillance systems in June 2023, was caused by a rare strain of Shiga toxin-producing Escherichia coli, or STEC.  This strain is known for causing severe gastrointestinal symptoms, including bloody diarrhea, abdominal pain, fever, and vomiting.

While the precise source of contamination remains elusive, the investigation has narrowed down the likely culprit to minced beef products.  Ten of the patients filled out questionnaires to provide a detailed account of their food history for the two weeks leading up to the onset of sickness.  All 10 reported eating either beef burgers, beef mince prepared at home, or other beef mince products.

Denmark – More outbreaks of Salmonella in 2023

SSI

In Denmark, the number of salmonella outbreaks increased from 2022 to 2023. This is evident from the annual report on zoonoses in Denmark, prepared by the DTU Food Institute, the Danish Food and Drug Administration and the Staten Serum Institut.

In Denmark, 18 salmonella outbreaks were registered in 2023, which is a significant increase from 2022, when there were 11 outbreaks. This appears from the annual report for 2023 on the incidence of zoonoses – diseases that can be transmitted from animals and food to humans.

The largest salmonella outbreak in 2023 in Denmark counted 31 registered cases of illness and was caused by Salmonella Munich. 8 of the Salmonella outbreaks in Denmark in 2023 are due to Salmonella Enteritidis. In total, around 200 patients were infected with different types of salmonella.

Increase in outbreaks with Salmonella Enteritidis also in Europe

The increasing number of outbreaks is also seen elsewhere in Europe and follows a general trend. Four of the 11 outbreaks of Salmonella Enteritidis detected in Denmark in 2023 can be traced back to larger international outbreaks.

EFSA, the European Food Safety Authority, reports that European countries have reported several outbreaks in 2023. EFSA’s database contains results from genetic analyzes of the bacteria, which have contributed to clarifying and tracing both the meat and the companies where the salmonella originates.

“When several countries in Europe contribute to the same database, we have a better chance of clarifying more European foodborne outbreaks. And we can see that salmonella can be linked to imported chicken meat,” says research group leader Marianne Sandberg from the DTU Food Institute. Salmonella Enteritidis is more often found in hens, chickens and eggs than in foods of other animal origin. Humans can become infected through contact with animals or food that is infected with the bacteria.

“Salmonella Enteritidis is an infection we most often see after people have traveled. It was therefore surprising that the number of Salmonella Enteriditis outbreaks within the country’s borders increased from 1-3 per year in 2017-2022, to 8 in 2023,” says Luise Muller, epidemiologist from the Statens Serum Institut.

The source of infection for one outbreak was fried chicken meat for kebabs. That particular outbreak was part of an international outbreak and involved over 200 patients in 13 countries. There are no indications that Danish-produced eggs or chicken meat were the cause of the salmonella outbreak.

“In Denmark, we have a very fine-tuned control for salmonella in the production of broilers and eggs for human consumption. If we find salmonella, eggs or chicken meat from the flocks must not be sent out to consumers, but must be heat treated,” says specialist consultant Gudrun Sandø from the Danish Food and Drug Administration.

Research – Say Goodbye to Spoiled Food With New Smart Packaging

Scitech Daily

Researchers at McMaster University have created smart packaging that detects spoilage, potentially reducing global costs by minimizing waste and illness. Despite its benefits, adoption faces hurdles due to cost concerns and regulatory challenges.

A team of researchers from McMaster University has invented a suite of tests for food packages that can indicate if the contents are contaminated, aiming to reduce food waste and prevent illnesses. They are now focusing on integrating this smart packaging technology into commercial products by engaging with producers and regulators.

Research – How to Improve Surveillance Program for Shiga Toxin-Producing E. coli (STEC): Raw Milk – Gap Analysis and Pilot Study

MDPI

Abstract

Several pathotypes of enteric E. coli have been identified. The group represented by Shiga toxin-producing E. coli (STEC) is of particular interest. Raw milk and raw milk products are significant sources of STEC infection in humans; therefore, identifying pathogens at the herd level is crucial for public health. Most national surveillance programs focus solely on raw milk and raw milk cheeses that are ready for retail sale, neglecting the possibility of evaluating the source of contamination directly at the beginning of the dairy chain. To assess the viability of the application of new molecular methodologies to STEC identification in raw milk filters and in calf feces, we analyzed 290 samples from 18 different dairy herds, including 88 bulk tank milk (BTM), 104 raw milk filters (RMF), and 98 calf feces samples. In total 3.4% of BTM, 41.4% of RMF, and 73.4% of calves’ feces were positive for stx, supporting our hypothesis that BTM is not a suitable matrix to assess the presence of STEC at herd level, underestimating it. Our conclusion is that the surveillance program needs critical and extensive improvements such as RMF and calves’ feces analysis implementation to be more efficient in detecting and preventing STEC infections. The epidemiology of these infections and the characteristics of the pathogen clearly show how a One Health approach will be pivotal in improving our capabilities to control the spread of these infections.

USA – 2024 Update: BAM Chapter 5: Salmonella

FDA

May 2024: Added a Salmonella screening section (Section D) to include generic LAMP and
qPCR protocols; added a table (Appendix A) to list validated matrices by the two molecular
methods; revamped Introduction to include a flow chart; updated Sections C.7 and C.24 on
matrices and preenrichment broths including an alternative formula for modified buffered
peptone water (M192c); deleted discontinued test kits in Section F.9. Original Section D and
Section E from all previous versions were shifted to Section E and Section F, respectively
because of the addition of Salmonella screening Section D.

PDF

Catalonia – Listeria/Listeriosis

ACSA

Listeriosis is a serious infection caused by the bacterium Listeria monocytogenes . It is a disease transmitted by food , which is relatively rare but serious, with high fatality rates (between 10% and 30%). People can get listeriosis after eating contaminated food. 

Video and more information at the link above

Research – Virulence Potential and Antimicrobial Resistance of Listeria monocytogenes Isolates Obtained from Beef and Beef-Based Products Deciphered Using Whole-Genome Sequencing

MDPI

Abstract

Listeria monocytogenes is a ubiquitous bacterial pathogen that threatens the food chain and human health. In this study, whole-genome sequencing (WGS) was used for the genomic characterization of L. monocytogenes (n = 24) from beef and beef-based products. Multilocus Sequence Type (MLST) analysis revealed that ST204 of CC204 was the most common sequence type (ST). Other sequence types detected included ST1 and ST876 of CC1, ST5 of CC5, ST9 of CC9, ST88 of CC88, ST2 and ST1430 of CC2, and ST321 of CC321. Genes encoding for virulence factors included complete LIPI-1 (pfrAhlyplcAplcBmplactA) from 54% (13/24) of the isolates of ST204, ST321, ST1430, and ST9 and internalin genes inlABC that were present in all the STs. All the L. monocytogenes STs carried four intrinsic/natural resistance genes, fosXlinnorB, and mprF, conferring resistance to fosfomycin, lincosamide, quinolones, and cationic peptides, respectively. Plasmids pLGUG1 and J1776 were the most detected (54% each), followed by pLI100 (13%) and pLM5578 (7%). The prophage profile, vB_LmoS_188, was overrepresented amongst the isolates, followed by LP_101, LmoS_293_028989, LP_030_2_021539, A006, and LP_HM00113468. Listeria genomic island 2 (LGI-2) was found to be present in all the isolates, while Listeria genomic island 3 (LGI-3) was present in a subset of isolates (25%). The type VII secretion system was found in 42% of the isolates, and sortase A was present in all L. monocytogenes genomes. Mobile genetic elements and genomic islands did not harbor any virulence, resistance, or environmental adaptation genes that may benefit L. monocytogenes. All the STs did not carry genes that confer resistance to first-line antibiotics used for the treatment of listeriosis. The characterization of L. monocytogenes in our study highlighted the environmental resistance and virulence potential of L. monocytogenes and the risk posed to the public, as this bacterium is frequently found in food and food processing environments.