Category Archives: Research

Research – Microbial safety and sanitary quality of strawberry primary production in Belgium: risk factors for Salmonella and Shiga toxin producing Escherichia coli (STEC) contamination.

AEM

Hepatitis A kswfoodworld

Strawberries are an important fruit in Belgium both in production and consumption, but little information is available about the presence of Salmonella and STEC in these berries, the risk factors in agricultural production and possible specific mitigation options. In 2012, a survey was undertaken of three soil and three soilless cultivation systems in Belgium. No Salmonella spp. was isolated. No STEC was detected in the strawberry samples (0 out of 72), but STEC was detected by qPCR in 11 out of 78 irrigation water and 2 out of 24 substrate samples.

Culture isolates were obtained for 2 out of 11 qPCR positive irrigation water samples and 2 out of 2 substrate samples. Multivariable logistic regression analysis revealed elevated generic E. coli numbers (odds ratio (OR) for 1 log increase being 4.6) as the most important risk factor for STEC, together with the berry picking season (elevated risk in summer).

Presence of generic E. coli in the irrigation water (≥ 1 cfu per 100 ml) was mainly influenced by the type of irrigation water (collected rainfall water stored in ponds was more often contaminated than ground water pumped from boreholes (OR = 5.8)) and the lack of prior treatment (untreated water versus water subjected to sand filtration prior to use (OR = 19.2)).

The follow-up study in 2013 at one of the producers indicated cattle as the most likely source of STEC contamination of the irrigation water.

Research – Vacuum-Packed Steak Tartare: Prevalence of Listeria monocytogenes and Evaluation of Efficacy of ListexTM P100

MDPI

Steak tartare is a raw, ready-to-eat meal popular in European countries, the safety of which is often discussed due to the risk of foodborne illness. The aim of this study was to determine the prevalence of Listeria monocytogenes in vacuum-packed steak tartare from retailers in the Czech Republic, characterize the strains obtained by typing methods and to evaluate the efficacy of ListexTM P100 against L. monocytogenes artificially inoculated into steak tartare samples. The prevalence of L. monocytogenes was 55% and 17 isolates belonging mostly to serotype 1/2a were obtained. Altogether 11 sequence types and 11 clonal complexes were assigned based on the whole genome sequencing (WGS) signifying the high diversity of L. monocytogenes isolates obtained. Core genome multi-locus sequence typing (cgMLST) did not confirm an epidemiological connection with human cases of listeriosis. The efficacy of ListexTM P100 treatment at concentrations of 108 and 109 PFU/g on artificially inoculated beef steak tartare samples was not efficient. Based on the results of this study, steak tartare from retailers can be considered as a source of L. monocytogenes that remains a challenge to the food industry. View Full-Text

Research – IFST – Building biofilm knowhow.

IFST

Mark Richardson outlines the aims and activities of the National Biofilms Innovation Centre (NBIC) and explains why the occurrence of foodborne pathogens in biofilms is a major concern.

The National Biofilms Innovation Centre (NBIC) is still a relatively young organisation but we are proud of what we have achieved since our formation in late 2017. We were funded through UKRI (UK Research and Innovation) by BBSRC (Biotechnology and Biological Sciences Research Council), Innovate UK and the Hartree Centre as an Innovation Knowledge Centre (IKC) to support and connect the biofilm community in industry and academia.

Foodborne pathogens within biofilms

Biofilms are communities of microorganisms (often multiple species) within an extracellular matrix associated with a surface; this allows them to communicate and collectively behave very differently to individual organisms. Biofilms have a role to play across multiple industrial sectors in terms of both the problems they present and opportunities they offer. In respect to human health and food they can, for example, potentiate the emergence of bacterial resistance to antibiotics, antiseptics and disinfectants. From farm to fork they have a role to play in the health of soils, plants and animals; in addition they impact on food processing and then subsequently on supply chain safety (particularly for ready to eat or chilled produce).

For example, Listeria monocytogenes, a pathogenic bacterium found in moist environments, soil, water, decaying vegetation and animals, can survive and even grow under refrigeration and other food preservation measures. It can cause food poisoning if ingested and due to the severity of infection and high case fatality rate, listeriosis is an important public health concern. A high level of vigilance is maintained in food manufacturing environments for the occurrence of this organism. There were 142 cases of food borne listeriosis in the UK in 2019 resulting in 23 deaths plus eight miscarriages or stillbirths.

Listeria monocytogenes typifies the problems that biofilm modality imparts to organisms in that when it grows within a biofilm, it is very difficult to detect, remove and destroy. When measures relating to its control go wrong, this can lead to significant human health issues, adverse impacts on the food sector’s reputation and significant economic costs. As recently as July 2021, Tyson Foods in the USA recalled nationally almost 4100 tonnes of ready-to-eat chicken products after finding they may have been contaminated with Listeria. The US Department of Agriculture announced the recall a month after two consumers reported falling ill with listeriosis. Further investigation revealed one death.

Australia/New Zealand – Call for comment on new food safety management standards 

FSANZ

Food Standards Australia New Zealand (FSANZ) is seeking public comment on proposed new food safety management standards for food service and retail businesses.

Interim FSANZ CEO Dr Sandra Cuthbert said the proposed amendments to the Australia New Zealand Food Standards Code (the Code) were designed to strengthen food safety management practices and introduce nationally consistent, risk-proportionate standards to reduce rates of foodborne illness.

“The food services sector is vitally important to the Australian economy and our way of life,” Dr Cuthbert said.

“The majority of businesses do an excellent job in providing Australians with safe food, however our assessment of food safety management practices in the sector has found a need for strengthened standards to ensure greater consistency and reduce rates of foodborne illness.

“The proposed changes will help food businesses enhance their food safety management practices, delivering safer food to consumers and supporting improved business and consumer confidence. The food service sector has demonstrated their responsiveness to enhancing safety throughout the COVID-19 pandemic, with food businesses and handlers rising to the challenge of meeting COVID health and safety requirements.”

FSANZ considered three specific food safety measures to reduce rates of foodborne illness – having a food safety supervisor on staff, training food handlers and ensuring businesses can provide evidence to substantiate food safety management.

Risk-proportionate regulation is proposed, with targeted measures to apply to businesses based on their level of food safety risk.

“Businesses will fall into one of three categories, with those associated with high food safety risks required to apply more food safety measures than those with lower risks,” Dr Cuthbert said.

“FSANZ considers these requirements are appropriate and practical, can be readily implemented in the relevant sector, and are able to be maintained over time.

“Regulatory measures would be supported by food safety culture initiatives and an education campaign for businesses and environmental health officers.

“This approach aims to provide the greatest impact on reducing foodborne illness in Australian food service and retail settings without unnecessary regulatory burden.”

FSANZ invites comments from interested parties on the proposed measures by 6pm (Canberra time) 11 April 2022.

FSANZ will consider all submissions before making a final decision. All FSANZ decisions on proposals to develop or update standards are notified to the ministers responsible for food regulation in Australia and New Zealand. They can ask for a review or agree that the standard should become law.

More information

Media contact:

  • 0401 714 265 (Australia)
  • +61 401 714 265 (New Zealand)

Research – Spain – Report of the Scientific Committee of the Spanish Agency for Food Safety and Nutrition (AESAN) on the safety of foods air-dried outdoors that are produced by traditional methods and which require an adjustment of the hygiene requirements that must be fulfilled

AESAN

Abstract
The European Union recognises that traditional methods of food production are a valuable and irreplaceable heritage that must be preserved over time. Therefore, Regulation (EC) No. 852/2004 permits a degree of flexibility in its application provided food hygiene goals are not compromised. For decades, both plant and animal-based foods have been produced in Spain which are air-dried outdoors until reaching a low water activity (aw) that enables their preservation at room temperature. These foods include, raisins, dried apricots, dried figs, ñora peppers, dried fish or octopus that are at least partially air-dried, among others.
The Scientific Committee of the Spanish Agency for Food Safety and Nutrition (AESAN) is of the opinion that the processing of naturally dried foods leads to their correct preservation, provided they reach an aw that inhibits the proliferation of pathogenic microorganisms and the production of toxins in them. Some of the stages in the process may cause microbial inactivation.
Above all, it is necessary to ensure the absence of the formation of toxins, with aflatoxins being the ones that have been most frequently identified. Thus, it is considered that the drying should be conducted in the least time possible, ensuring a decrease of aw within the first 2-3 days of below 0.90 to inhibit the development of aflatoxins, and this drying should be continued until aw levels lower than 0.70 are reached, preventing the growth of pathogenic microorganisms that cause spoilage. It is necessary to guarantee suitable hygienic conditions during processing in order to prevent contamination by pathogens and/or toxins.
Although they cannot proliferate in the stated preservation conditions, they can remain viable in the final product, therefore they may pose a risk to consumer health. Microorganisms with a low infective dose and those that have been identified in dried products (such as S. aureus and Salmonella) and microbial toxins are especially relevant. Autonomous Communities must monitor compliance with the requirements to ensure that they do not pose a risk in these products.
Although these types of products have a low aw, within the range of 0.6 to 0.8 according to avail-able literature, given that this information is not available for each assessed product, the level of safety reached cannot be established on an individual basis. Additionally, the diverse factors used in some of them (additives and preservatives, pasteurisation processes, etc.) require individual assessment once all the necessary information is available. Therefore, the drying must reach aw levels below 0.70 in the least time possible for these types of products to be considered stable, as given these conditions, there is no scientific evidence that shows that the safety and stability of the dried products are compromised, provided good hygiene practices are maintained during their preservation and storage.
For final levels of aw that are higher, correct preservation may be achieved through a combination of factors which proves that it is effective throughout the shelf life of the product, maintaining the aforementioned appropriate hygiene practices.

Research – Emerging Legionella species data

HPS

Legionella_Plate_01

08 February 2022

Article: 56/502

In July 2021, the Legionella Control Association (LCA), in conjunction with the Health and Safety Executive (HSE), Public Health England (PHE) and local authorities, held a webinar aimed at raising awareness of increasing Legionella positivity rates post lockdown.  The data demonstrated that the average positive rate in the UK had increased by around 2% following the lockdowns in response to COVID-19.

To investigate if there were particular species that could have led to this increase, LCA approached the three commercial laboratories in the UK that use MALDI-ToF to confirm down to species level, and asked if they would share their data. This information has now been returned by some laboratories, with findings from over 70,000 positive result samples in a two-year period revealing:

  • over 53% of the results were L.anisa
  • over 32% of the positives were L. pneumophilia, both SeroGroup 1 and SeroGroup 2-15
  • nearly 1% of positives were for L. rubilucens
  • over 6.5% of the results did not confirm a species type
  • there were over a dozen other species identified in results that accounted for less than 1% of the data set

The first line clinical diagnostic tool used to confirm Legionnaire’s disease in the UK is commonly a urinary antigen test (UAT), and this method looks predominantly for L. pneumophilia SeroGroup 1. Given the data LCA has provided so far, this could potentially mean missing over 70% of Legionella infections in patients. It should be highlighted that this data is in its infancy, and LCA state that further research needs to take place before any significant changes are considered or undertaken.

Source: LCA, January 2022

South Africa – A systematic review on mobile health applications for foodborne disease outbreak management

BMC

Abstract

Background

Foodborne disease outbreaks are common and notifiable in South Africa; however, they are rarely reported and poorly investigated. Surveillance data from the notification system is suboptimal and limited, and does not provide adequate information to guide public health action and inform policy. We performed a systematic review of published literature to identify mobile application-based outbreak response systems for managing foodborne disease outbreaks and to determine the elements that the system requires to generate foodborne disease data needed for public action.

Methods

Studies were identified through literature searches using online databases on PubMed/Medline, CINAHL, Academic Search Complete, Greenfile, Library, Information Science & Technology. Search was limited to studies published in English during the period January 1990 to November 2020. Search strategy included various terms in varying combinations with Boolean phrases “OR” and “AND”. Data were collected following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement. A standardised data collection tool was used to extract and summarise information from identified studies. We assessed qualities of mobile applications by looking at the operating system, system type, basic features and functionalities they offer for foodborne disease outbreak management.

Results

Five hundred and twenty-eight (528) publications were identified, of which 48 were duplicates. Of the remaining 480 studies, 2.9% (14/480) were assessed for eligibility. Only one of the 14 studies met the inclusion criteria and reported on one mobile health application named MyMAFI (My Mobile Apps for Field Investigation). There was lack of detailed information on the application characteristics. However, based on minimal information available, MyMAFI demonstrated the ability to generate line lists, reports and offered functionalities for outbreak verification and epidemiological investigation. Availability of other key components such as environmental and laboratory investigations were unknown.

Conclusions

There is limited use of mobile applications on management of foodborne disease outbreaks. Efforts should be made to set up systems and develop applications that can improve data collection and quality of foodborne disease outbreak investigations.

Research – Bacterial Antagonistic Species of the Pathogenic Genus Legionella Isolated from Cooling Tower

MDPI

Legionella pneumophila is the causative agent of Legionnaires’ disease, a severe pneumonia. Cooling towers are a major source of large outbreaks of the disease. The growth of L. pneumophila in these habitats is influenced by the resident microbiota. Consequently, the aim of this study was to isolate and characterize bacterial species from cooling towers capable of inhibiting several strains of L. pneumophila and one strain of L. quinlivanii. Two cooling towers were sampled to isolate inhibiting bacterial species. Seven inhibitory isolates were isolated, through serial dilution plating and streaking on agar plates, belonging to seven distinct species. The genomes of these isolates were sequenced to identify potential genetic elements that could explain the inhibitory effect. The results showed that the bacterial isolates were taxonomically diverse and that one of the isolates may be a novel species. Genome analysis showed a high diversity of antimicrobial gene products identified in the genomes of the bacterial isolates. Finally, testing different strains of Legionella demonstrated varying degrees of susceptibility to the antimicrobial activity of the antagonistic species. This may be due to genetic variability between the Legionella strains. The results demonstrate that though cooling towers are breeding grounds for L. pneumophila, the bacteria must contend with various antagonistic species. Potentially, these species could be used to create an inhospitable environment for L. pneumophila, and thus decrease the probability of outbreaks occurring. View Full-Text

Research – Comparative efficiency of carbohydrates on the biofilm-forming ability of enteroaggregative Escherichia coli

Wiley Online

The biofilm-forming ability of microbes is often correlated with drug resistance; however, this association among enteroaggregative Escherichia coli (EAEC) strains remains naïve. Moreover, the investigations exploring uptake and assimilation of sugars either qualitatively or quantitatively by the biofilm-forming EAEC strains have not yet been documented. Hence, this study investigated the role of various categories of sugars (monosaccharides, disaccharides, and polysaccharide) on the biofilm-forming ability of three each of multi-drug-resistant (MDR) as well as non-MDR typical EAEC strains. The EAEC strains exhibited black colonies on congo red agar (CRA) with monosaccharides and disaccharides, whereas all the strains exhibited red colonies on CRA with the polysaccharide. Although significant (p < 0.001) biofilm-forming ability was observed by all the EAEC strains in sugar-dependent microtiter plate assay, color change from pink to orange and yellow was noticed in presence of monosaccharides and disaccharide, while absent in polysaccharides. Besides, significantly higher bacterial counts were observed in presence of monosaccharides and disaccharides (p < 0.01); however, such significant bacterial counts were not noticed with the polysaccharide. Further, the real-time PCR data exhibited comparatively higher relative expression of biofilm-associated fis gene among EAEC strains grown in presence of monosaccharides, followed by disaccharide and polysaccharide, respectively that concurred with the flow cytometry data. No significant (p > 0.05) difference was observed in the biofilm-forming ability between MDR- and non-MDR EAEC strains. This study illustrated the role of carbohydrates on the biofilm-forming ability of EAEC and warranted utmost attention concerning the usage of carbohydrates in food processing industries, for its incorporation as functional food additives.

Research – Effect of hydrophobic/hydrophilic characteristics of B. cereus spores on their resistance to detergents

Journal of Food Protection

Bacillus cereus spores have the ability to adhere to solid surfaces, including stainless steel, a material widely used in food industries. Adhesion of spores allows for recontamination during food processing, and the cleaning and disinfection are largely used by industries to control them. Hence, this study aims to assess the detachment capacity (or removing activity) of sodium hydroxide, nitric acid, phosphoric acid-based detergent, chlorine-based detergent; against two adhered Bacillus cereus spores (hydrophobic strain and hydrophilic strain) to stainless steel surfaces. Microorganism adhesion on the surfaces reached 5.5 log CFU/cm² the two strain studied. Two protocols composed of combinations of chemical compounds concentration, temperature, and contact time were tested. The inactivation kinetics shapes were convex and were modelled by the Weibull model. The effect of temperature and biocide concentration were quantified using a Bigelow like model. The temperature applied during of treatment of the cleaning in place is an important factor acting on the speed of inactivation or detachment of Bacillus cereus spores. However, this efficiency depends on the hydrophobic characteristics of Bacillus cereus spores. The concentration of detergent and acid also affects the inactivation rate. The inactivation rate, whereas the character of hydrophobic does not intervene for the chlorine alkaline treatments.