Category Archives: Food Microbiology Research

Research – Reporting delay likely impacted size of sandwich Listeria outbreak

Food Safety News

Later infections in a deadly Listeria outbreak traced to sandwiches served in hospitals in England could have been prevented, according to an investigation into the incident.

The first outbreak patient in April 2019 was not confirmed for almost two months because Public Health England did not get the isolate for typing from the hospital until early June.

Officials said it was “conceivable” that earlier receipt of the isolate would have raised the possibility of a wider problem sooner and may have led to earlier intervention and prevention of some further cases in the outbreak. Referral of clinical isolates is voluntary. Experts say making such action mandatory should be considered.

EU – EU project uses phages to tackle Campylobacter in poultry

Food Safety News

A European project has developed a way to help with the biocontrol of Campylobacter and reduce its prevalence in the poultry sector.

Work focuses on the development of a bacteriophage-based solution to be used as a natural antimicrobial in the farm (pre-harvest), at slaughter, and in processing facilities (post-harvest). Standard control measures at the farm level rely upon the use of antibiotics.

The project, called Campylobacter-Specific Nullification via Innovative Phage-mediated Enteropathogen Reduction (C-SNIPER), is led by AZTI, a technology center in Spain. It received funding from EIT Food, part of the European Institute of Innovation & Technology (EIT), a body of the European Union.

Poultry is the most widely consumed meat in the EU with Poland, Italy, Spain, and Germany as major producers. However, the consumption of poultry products is also considered the main route for campylobacteriosis, the most frequently reported foodborne illness in Europe.

USA – Fresh Express Inc – Div of Chiquita Brands – FDA Warning Letter

FDA

The U.S. Food and Drug Administration (FDA ) inspected your bagged salad operation located at 1109 East Lake Street, Streamwood, IL 60107, from June 25, 2020 through July 23, 2020. The inspection was initiated as part of an investigation of a multistate foodborne outbreak of cyclosporiasis (human infections with the parasite Cyclospora cayetanensis). As of September 23, 2020, the Centers for Disease Control and Prevention (CDC) reported that at least 701 people from 14 states have been infected with Cyclospora cayetanensis. Based on epidemiological and traceback evidence, CDC and FDA have determined that bagged salad mixes containing iceberg lettuce, carrots, and red cabbage manufactured at your Streamwood, IL facility were the source of this multistate cyclosporiasis outbreak. On June 19, 2020, you recalled bagged salad mix containing iceberg lettuce, red cabbage, and carrots, because they had the potential to be contaminated with Cyclospora. The Public Health Agency of Canada is also investigating an outbreak of cyclosporiasis infections occurring in three Canadian provinces in which Fresh Express brand salad products containing iceberg lettuce, carrots, and red cabbage have been identified as the likely source of the outbreak. This is the second outbreak of cyclosporiasis linked to Fresh Express product. In 2018, a multistate foodborne outbreak of cyclosporiasis involving 511 confirmed cases from 15 states was linked to salads sold at a fast food restaurant and manufactured at your Streamwood, IL facility.

Research – Consecutive Treatments with a Multicomponent Sanitizer Inactivates Biofilms by Escherichia coli O157:H7 and Salmonella enterica and Removes Biofilm Matrix

Journal of Food Protection

Many foodborne pathogens including E. coli O157:H7 and Salmonella enterica can develop biofilms on contact surfaces at meat processing plants. Due to the high tolerance of the biofilm cells associated with the 3-dimensional biofilm structure and the well-expressed bacterial polymeric extracellular substances (EPS), it is a real challenge to completely inactivate and remove mature biofilms as well as further prevent biofilm reoccurrence and pathogen survival. We evaluated the effectiveness of consecutive treatments by repeatedly applying a multicomponent sanitizer, based on the functional mechanism by synergistic combination of hydrogen peroxide and quaternary ammonia compounds, against biofilms by E. coli O157:H7 and Salmonella strains. Biofilms were treated with 2.5%, 5%, or 10% of the sanitizer applied as foam or liquid solution. The sanitizer at all concentrations significantly reduced the amount of viable biofilm cells as enumerable bacteria were only detected after low concentration treatments (2.5% or 5%) with short exposure periods. Treatments with high concentrations (5% or 10%) of the sanitizer, multiple consecutive treatments and sufficient exposure time effectively controlled pathogen post-sanitization survival. Examination with a scanning electron microscope showed that treatment with the sanitizer at 5% strength significantly dissolved the connecting EPS matrix and removed most of the biofilm matrix. No intact biofilm structure was detected after the 10% sanitizer treatment, instead, scattered individual bacteria with visibly altered cell morphology were observed. The treated bacteria exhibited indented and distorted shapes with shortened cell length and increased surface roughness, indicating severe cell injury and death.  Our observations indicated that consecutive treatments with the multicomponent sanitizer was effective in inactivating E. coli O157:H7 and Salmonella enterica biofilms and preventing pathogen reoccurrence.

Research – Assessment of stabilized hydrogen peroxide for use in reducing Campylobacter levels and prevalence on broiler chicken wings

Journal of Food Protection

Poultry processing establishments utilize antimicrobial processing aids on broiler parts to minimize Campylobacter contamination. A stabilized hydrogen peroxide (SHP) product was assessed for use as an antimicrobial processing aid. In a series of experiments, wing segments with skin were inoculated with 103 – 107 cells of Campylobacter coli followed by treatment with SHP at 15,000 or 30,000 mg/L, peroxyacetic acid at 300 or 3,000 mg/L (ppm), or water. Each treatment was applied by either dip or spray. Rinsates from each wing segment were analyzed for direct counts and prevalence of Campylobacter. Treatment with SHP or PAA significantly reduced Campylobacter levels compared to water controls by up to 2.22 log CFU/mL. At high inoculum levels (106 – 107), SHP and PAA applied by dip had up to 1.27 log CFU/mL further reductions of Campylobacter levels as compared to spray treated wing segments. Additionally, wing drumettes were observed to retain higher levels and prevalence of Campylobacter recovery compared to wing flats at a low inoculation level (103). The results indicated that there was no carry-over effect of SHP (same day vs. 24 h) and dip treatment with SHP or PAA decreased Campylobacter recovery on broiler chicken wing segments compared to a water control. Although 2 log reductions were modest, SHP had similar efficacy as the commonly used processing aid, PAA. SHP shows potential for further investigation as an antimicrobial processing aid for use on poultry parts.

Research – Salmonella contamination of broiler chicken carcasses at critical steps of the slaughter process and in the environment of two slaughter plants

Journal of Food Protection

Research – A bacterial virus helped the spread of a new Salmonella strain

Phys Org.

Salmonella is associated with a large number of cases of foodborne infection resulting in diarrhea and in some cases severe complications. Half of all Salmonella infections in the European Union are linked to pigs, and a new strain called ST34 is dominant in this livestock animal. ST34 has now spread in pig populations worldwide and is pandemic.

The research was led by Eleonora Tassinari and Professor Rob Kingsley from the Quadram Institute and University of East Anglia and his research group, working with Public Health England, Animal and Plants Health Agency, the Earlham Institute and Teagasc Food Research Center. Their study was funded by the Biotechnology and Biological Sciences Research Council, part of UKRI.

They found that the common ancestor of the epidemic in UK pigs existed around 30 years ago but went unnoticed until 2005 when surveillance by the UK governments Animal and Plant Health Agency (APHA) first picked up ST34 in low numbers. Analysis of the genome sequence from human infections using data from Public Health England (PHE) indicated that a bacterial virus called mTmV infected ST34 on multiple occasions starting around 2002.

Research – Quantification of survival and transfer of Salmonella on fresh cucumbers during waxing

JFP

Cucumbers found in retail markets are often waxed to improve visual appeal and retard moisture loss. This waxing may affect bacterial survival and the waxing process may facilitate cross-contamination between cucumbers. This study assessed survival of Salmonella on waxed and un-waxed cucumbers and the potential for Salmonella cross-contamination during the waxing process. Fresh waxed or un-waxed cucumbers were spot-inoculated with a Salmonella enterica cocktail. Three different wax coatings (mineral oil, vegetable oil, or petroleum wax) were manually applied to un-waxed cucumbers using polyethylene brushes. Salmonella transfer from inoculated cucumbers to brush or to un-inoculated cucumbers was quantified. Higher Salmonella concentrations were observed on waxed cucumbers during the first 3 days of storage but the final concentration on un-waxed cucumbers was higher than on waxed cucumbers at the end of storage, regardless of storage temperature. Wax formulation did affect survival of Salmonella inoculated directly into waxes, with the significant decline in Salmonella populations observed in vegetable-based wax coating, but with populations unchanged over 7 days at 7 or 21 °C in mineral oil-based and petroleum-based waxes. Salmonella cells could transfer from inoculated un-waxed cucumbers to brushes used for waxing and then to un-inoculated cucumbers during waxing. Significantly higher log percent transfer to brushes was observed when cucumbers were waxed with vegetable oil (0.71 log percent, P = 0.00441) vs. mineral oil (0.06 log percent) or petroleum (0.05 log percent). Transfer to un-inoculated cucumbers via brushes was also quantified (0.18 to 0.35 log percent transfer). Salmonella remaining on contaminated cucumbers after waxing could be detected for up to 7 days, and Salmonella survived better on cucumbers treated with a petroleum-based wax. These findings should be useful in managing risk of Salmonella contamination in cucumbers during post-harvest handling.

Scotland – The risk of STEC contamination in wild venison

FSS

Summary

We have published this report to address knowledge gaps and better understand the risk of STEC (Shiga toxin-producing Escherichia coli) contamination of wild venison.

The report is based on three core objectives to:

  • map the venison industry in Scotland
  • assess STEC prevalence in wild deer faeces in Scotland
  • review cross-contamination risks in the slaughter and processing stages of wild deer from the field to larder

Although the prevalence of STEC O157 in wild deer is low, the report found that when discovered, it is the strain associated with the most severe forms of human disease. Therefore, adherence to strict hygiene practices from cull to final product are strongly recommended within the report.

The venison industry continues to take a cooperative and responsible approach to STEC O157 when found, working to better understand the risks in the sector and how to mitigate them in the interest of public health protection.

Research – Investigation into a national outbreak of STEC O157:H7 associated with frozen beef burgers, UK, 2017

Cambridge Org

In November 2017, Public Health England identified an outbreak of Shiga toxin-producing Escherichia coli O157:H7 in England where whole genome sequencing results indicated cases were likely to be linked to a common source, and began investigations. Hypothesis generation included a review of enhanced surveillance data, a case-case study and trawling interviews. The hypothesis of interest was tested through the administration of focussed questionnaires and review of shopping history using loyalty card data. Twelve outbreak cases were detected, eight were hospitalised and four developed haemolytic uraemic syndrome. Frozen beef burgers supplied by a national retailer were identified as the vehicle of the outbreak. Testing of two left-over burger samples obtained from the freezers of two separate (unlinked) cases and a retained sample from the production premises were tested and found to be positive for the outbreak strain. A voluntary recall of the burgers was implemented by the retailer. Investigations at the production premises identified no contraventions of food safety legislation. Cooking guidance on the product packaging was deemed to be adequate and interviews with the cases/carers who prepared the burgers revealed no deficiencies in cooking practices at home. Given the long-shelf life of frozen burgers, the product recall likely prevented more cases.