Category Archives: Food Microbiology Research

Research – Prevalence and antimicrobial resistance of foodborne pathogens in select fresh produce procured from farmers’ markets in Central Virginia

Wiley Online

As farmers’ markets have increased in size, scope, and complexity, so have potential food‐safety challenges and implications. Most products sold at farmers’ markets may receive minimal to no treatment of decontamination which could increase their potential microbial risks. The aim of this study was to assess the prevalence and antimicrobial resistance (AMR) of foodborne pathogens in select fresh produce procured from farmers’ markets in Central Virginia. A total of 138 samples produced by 15 farms and sold at 9 registered farmers’ markets were obtained between March and November 2017. CampylobacterEscherichia coli, and Listeria were, respectively, detected in 8.7, 9.4, and 8.0% of the samples. A total of 46 bacterial isolates consisted of CampylobacterE. coli, and Listeria were tested for their susceptibility to 12 antimicrobials. Ampicillin resistance showed the highest frequency among Campylobacter (100%) and E. coli (47.8%) isolates while nalidixic acid resistance was the highest in Listeria isolates (72.7%). At least 17% of each CampylobacterE. coli, and Listeria isolates exhibited multidrug resistance (MDR). No isolates had matching pulsed‐field gel electrophoresis (PFGE) profiles demonstrating that the E. coli isolates had a high degree of genomic diversity. This study demonstrated a potential health hazard arising from farmers’ market‐acquired fresh produce and emphasizes the importance of good agricultural and handling practices to prevent foodborne illness and spread of multidrug antibiotic resistance. Continued research is needed to determine and intervene the cause(s) of the observed prevalence and to support the healthy development of food products sold at farmers’ markets.

Research UK – Listeriosis in England and Wales: summary for 2019

Gov

This report summarises the number and characteristics of confirmed cases of listeriosis in England and Wales in 2019:

  • 142 cases of listeriosis were reported in England and Wales
  • incidence rates of listeriosis were highest in people aged 80 years and over
  • overall, the crude incidence of listeriosis was lower in men than women, but reported cases among men aged 60 to 69 were 7 times higher than in women aged 60 to 69.
  • pregnancy-associated infections accounted for 17.6% of all reported cases and, a third of pregnancy-associated cases resulted in stillbirth or miscarriage
  • among non-pregnancy associated cases of listeriosis, death was reported for 23 cases (19.7%), of whom 15 (12.8%) were known to have listeriosis recorded as a cause of death on the death certificate
  • incidence of listeriosis varied geographically, with the lowest incidence in East of England (0.14 per 100,000 population) and the highest in London (0.39 per 100,0000 population)
  • there were 4 listeriosis outbreaks investigated in England, including a national outbreak associated with the consumption of prepacked hospital sandwiches

Listeriosis remains a rarely reported disease, with 0.24 cases per 100,000 population. Despite a decline in reported cases in 2019, the number of outbreaks (4) of listeriosis remained comparable to previous years. The outcome of listeriosis in pregnancy remains severe with over a third resulting in miscarriage or stillbirth. Mortality amongst non-pregnancy cases remained high, with a case fatality rate of 12.8%. An early peak in listeriosis cases was identified as a national outbreak, and food incidents linked to sporadic cases were identified through the analysis of strain relatedness using whole genome sequence data.

As a predominantly foodborne infection, this severe disease is largely preventable. It remains imperative that sporadic cases of illness and clusters of disease continue to be monitored and investigated to inform the continued risk assessment of the food chain.

Research – Efficacy of Bacteriophage Cocktail to Control E. coli O157:H7 Contamination on Baby Spinach Leaves in the Presence or Absence of Organic Load

MDPI

Fruits and vegetables are high in nutrients that are essential for a healthy lifestyle. However, they also harbor an extensive array of microorganisms such as bacteria, which can be beneficial, neutral, or pathogenic. Foodborne pathogens can contaminate produce at any stage from the farm to the consumer’s table. Appropriate washing techniques using sanitizers can reduce the risk of pathogen contamination. Issues related to maintaining concentration, efficacy, and other problems have been a challenge for the food industry and, when left unresolved, have led to different outbreaks of foodborne illnesses. In this study, the efficacy of a lytic bacteriophage cocktail was examined for its ability to infect and reduce the contamination of Escherichia coli O157:H7 (E. coli O157:H7), in media with a high organic load, using a microplate technique. The study was conducted for 3 h to determine if the bacteriophage cocktail could reduce the pathogen in the presence of a high organic load. A significant (p < 0.05) reduction in the population of E. coli O157:H7 was observed, representing a 99.99% pathogen reduction at the end of 3 h. Fresh spinach leaves were washed in sterile potable or organic water (~9000 ppm organic load) containing E. coli O157:H7 and a bacteriophage cocktail to study the effectiveness of bacteriophages against the foodborne pathogen. Results indicated that the bacteriophage significantly (p < 0.05) reduced the contamination of E. coli O157:H7 in both situations. The study also demonstrated the bacteriophages’ ability to infect and reduce the pathogen in an organic-rich environment. This characteristic differs from commercially available sanitizers that have demonstrated a tendency to bind with the available organic load. Thus, these studies highlight the advantage of employing bacteriophages during produce wash to eliminate foodborne pathogen contamination on fruits and vegetables. View Full-Text

Research – Campylobacter Contamination of UK-Produced Halal Chicken at Retail

Journal of Food Protection

CDC Campy

Campylobacter is the leading cause of human bacterial diarrhoeal disease worldwide, with poultry meat products accounting for the majority of human cases. Recent surveys by the Food Standards Agency estimate the Campylobacter prevalence in fresh UK retail chicken to be 41.2%. However, such surveys have not distinguished between broiler chickens produced for different consumer demographics, such as the Halal market. Campylobacter colonisation of broilers is difficult to prevent, especially during routine partial depopulation of flocks. Broilers produced for the Halal market may undergo multiple depopulation events, which may increase the risk of colonisation and subsequent Campylobacter contamination of chicken meat. This project aimed to determine the prevalence and levels of Campylobacter contamination of chicken meat produced for the UK Halal market. Campylobacter was identified and enumerated from the neck skin and outer packaging of 405 Halal chickens. Following culture, isolates were assigned to species via PCR and disc diffusion antimicrobial susceptibility tests determined. Logistic regression analysis assessed risk factors for Campylobacter isolation, the level of Campylobacter contamination among positive carcasses and antimicrobial resistance outcomes. Campylobacter spp. were confirmed in 65.4% of neck skin samples and 17.1% of packaging samples. 13.8% of neck skin samples had the highest level of contamination (>1000 cfu/g). Large birds had a significantly higher number of samples with >1000 cfu/g (p<0.001) and as chicken carcass weight increased, birds were more likely to be Campylobacter-positive (p<0.05). A high prevalence of resistance was seen to ciprofloxacin (42.0%) and 38.5% of samples contained at least one multi-drug resistant Campylobacter isolate. This study demonstrates that Halal chicken has a higher Campylobacter prevalence than non-Halal chicken. Interventions should be introduced to reduce this increased public health risk to consumers.

Research – Environmental Management of Legionella in Domestic Water Systems: Consolidated and Innovative Approaches for Disinfection Methods and Risk Assessment

MDPI

Legionella_Plate_01

Legionella is able to remain in water as free-living planktonic bacteria or to grow within biofilms that adhere to the pipes. It is also able to enter amoebas or to switch into a viable but not culturable (VBNC) state, which contributes to its resistance to harsh conditions and hinders its detection in water. Factors regulating Legionella growth, such as environmental conditions, type and concentration of available organic and inorganic nutrients, presence of protozoa, spatial location of microorganisms, metal plumbing components, and associated corrosion products are important for Legionella survival and growth. Finally, water treatment and distribution conditions may affect each of these factors. A deeper comprehension of Legionella interactions in water distribution systems with the environmental conditions is needed for better control of the colonization. To this purpose, the implementation of water management plans is the main prevention measure against Legionella. A water management program requires coordination among building managers, health care providers, and Public Health professionals. The review reports a comprehensive view of the state of the art and the promising perspectives of both monitoring and disinfection methods against Legionella in water, focusing on the main current challenges concerning the Public Health sector.

Research – Effect of Chlorine Dioxide Treatment on Human Pathogens on Iceberg Lettuce

MDPI

In the vegetable processing industry, the application of chlorine dioxide (ClO2) as a disinfectant solved in washing water to eliminate undesirable microorganisms harmful to consumers’ health and the shelf life of produce has been discussed for years. The disinfection efficacy depends on various factors, e.g., the location of microorganisms and the organic load of the washing water. The present study analyzed the sanitation efficacy of various concentrations of water-solved ClO2 (cClO2: 20 and 30 mg L−1) on Escherichia coli (1.1 × 104 cfu mL−1), Salmonella enterica (2.0 × 104 cfu mL−1) and Listeria monocytogenes (1.7 × 105 cfu mL−1) loads, located on the leaf surface of iceberg lettuce assigned for fresh-cut salads. In addition, it examined the potential of ClO2 to prevent the cross-contamination of these microbes in lettuce washing water containing a chemical oxygen demand (COD) content of 350 mg L−1 after practice-relevant washing times of 1 and 2 min. On iceberg leaves, washing with 30 mg L−1 ClO2 pronouncedly (1 log) reduced loads of E. coli and S. enterica, while it only insignificantly (<0.5 × log) diminished the loads of L. monocytogenes, irrespective of the ClO2 concentration used. Although the sanitation efficacy of ClO2 washing was only limited, the addition of ClO2 to the washing water avoided cross-contamination even at high organic loads. Thus, the application of ClO2 to the lettuce washing water can improve product quality and consumer safety. View Full-Text

UK – Update 12 March: The FSA is reiterating its advice on cooking frozen raw breaded chicken products following links to cases of Salmonella

FSA

The FSA is repeating advice to consumers following an updated recall linked to salmonella contamination.

SFC has issued an updated recall of chicken products because Salmonella Enteritidis (a food poisoning bug) has been found in some of these foods.

This update includes the original products identified in previous recalls as well as additional products.

Dr Colin Sullivan, Chief Operating Officer, FSA said:

‘The products are linked to two ongoing outbreaks of Salmonella Enteritidis (a food poisoning bug) in chicken from Poland.

‘The producer put additional controls in place to improve the safety of their products in November 2020. SFC has decided to withdraw and recall all of its chicken products produced before this date.

‘The FSA will be making additional checks to ensure the effectiveness of this withdrawal and recall.’

Products affected

The full list of products is available in the food alert.

Update on the wider Salmonella investigation

We are continuing to work with Food Standards Scotland (FSS), Public Health England (PHE), Public Health Scotland, Public Health Wales and the Public Health Agency in Northern Ireland as part of the ongoing investigation into two particular strains of Salmonella linked to frozen raw breaded chicken products from Poland.

We previously issued precautionary consumer advice in October 2020 and February 2021. Additional controls have been put in place by food businesses at production level. These changes to the production process are proving to be effective and we hope to see a further reduction in cases in the coming months as these products are removed from the food chain. While we continue these efforts, it is important that people carefully follow food hygiene advice.

Investigations are ongoing into identifying the source of the outbreaks at farm level in Poland. Should more products be identified actions to remove unsafe food will be taken.

Saheer Gharbia, Head of the Gastrointestinal Pathogens Unit of PHE’s National Infection Service, said:

‘While we appear to be past the peak of this outbreak, and case reporting rate has decreased in recent months, we are still detecting some cases through whole genome sequencing, so it is important that people carefully follow food hygiene advice. We continue to work closely with the Food Standards Agency to resolve the outbreak.

‘Salmonella generally causes a mild illness, although vulnerable groups like children under five years, the elderly, and those with weakened immune systems may experience more severe illness and may require hospitalisation. Symptoms of a Salmonella infection include diarrhoea, stomach cramps and sometimes vomiting and fever. Anyone who is concerned about symptoms should contact their GP or out of hours service in the first instance.’

Our advice to consumers

If consumers have bought any of the products in the updated recall, they can return them to the store where they were bought for a full refund.

We are encouraging consumers to always cook food at the right temperature and for the correct length of time to ensure any harmful bacteria are killed. Before serving these products, make sure they are steaming hot and cooked all the way through. When you cut into the thickest part of the meat, check that none of the meat is pink and that any juices run clear.

Anyone who is concerned about symptoms should contact their GP or out of hours service in the first instance.

Only the products listed in the recall notice are affected. There is no need to change your shopping habits for chicken products.

Research – In Vitro Screening of Chicken-Derived Lactobacillus Strains That Effectively Inhibit Salmonella Colonization and Adhesion

MDPI

nhibition of Salmonella by Lactobacillus has been a popular research topic for decades; however, the inhibition potential of chicken-derived Salmonella by chicken-derived Lactobacillus has not yet been studied. In this study, 89 strains of Lactobacillus from chicken intestines were isolated by national standard method, Gram staining, physiological, and biochemical experiments and molecular sequencing; The inhibition characteristics of 89 strains of chicken derived Lactobacillus against 10 strains Salmonella (S. Enteritidis SE05, SC31, SC21, SC72 SC74, SC79, SC83, SC87; S. bongori SE47; S. Typhimurium, SC85) were detected by agar inhibition zone, The results showed that the inhibition zone of 24 strains of chicken derived Lactobacillus was more than 10 mm, which indicated that the isolated chicken derived Lactobacillus could effectively inhibit the growth of Salmonella; The drug resistance and bile salt tolerance of these 24 strains were analyzed, The results showed that the standard strains LG and L76 were not resistant, and the other 22 Lactobacillus strains showed different degrees of resistance. The strains LAB24, LAB26, LAB53, LAB69, and L76 showed good tolerance at the concentration of 3 g/L bile salt; Caco-2 cell experiment and flow cytometry were used to analyze the inhibitory effect of chicken derived Lactobacillus on the adhesion of Salmonella to Caco-2 cells, The results showed that 16 probiotics could effectively inhibit the adhesion of Salmonella to Caco-2 cells. Twelve probiotics were identified by molecular biology. The results showed that L76 was Enterococcus faecalis, and the other 11 strains were Lactobacillus. View Full-Text

Research – Behavioral Ethics and the Incidence of Foodborne Illness Outbreaks

Springer

Cognitive biases play an important role in creating and perpetuating problems that lead to foodborne illness outbreaks. By using insights from behavioural ethics, we argue that sometimes people engage in unethical behaviour that increases the likelihood of foodborne illness outbreaks without necessarily intending to or being consciously aware of it. We demonstrate these insights in an analysis of the 2011 Listeriosis outbreak in the U.S. from the consumption of contaminated cantaloupes. We then provide policy implications that can improve our understanding of other kinds of disease outbreaks and epidemics.

Kenya – Tough Terms As Kenya Lifts Tanzania, Uganda Maize Imports Ban -Aflatoxin

All Africa

All stakeholders dealing in maize imports would be required to be registered, the consignments coming in must be accompanied with certificate of conformity on aflatoxin levels and that traders have to issue details of their warehouses and the certificate of conformity should indicate that the aflatoxin levels complies with the maximum required levels of 10 parts per billion, the Ministry of Agriculture said. This comes a week after Kenya banned the importation of maize from two neighbouring countries, Tanzania and Uganda, after studies revealed higher than normal levels of mycotoxins. In a letter to the neighbours, the Kenya Agriculture and Food authority said they were “conducting surveillance on the safety of food imports into Kenya”. Mycotoxins are naturally occurring toxins produced by certain fungi and can be found in food. It grows on a variety of different crops and foodstuffs including cereals, nuts, spices, dried fruits, apples and coffee beans, often under warm and humid conditions.