Category Archives: Food Microbiology Research

Research – Updated food safety guidance gives pregnant women more certainty and choice on a wider range of foods

MPI

New research from New Zealand Food Safety provides pregnant women with more options and certainty about what they can safely eat with updated tips to avoid foodborne illness.

“We’ve looked at new foods that were not previously considered because we want pregnant women to have the most up-to-date food safety information so they can enjoy a diverse diet and stay healthy,” says Dr Claire McDonald, Manager Operational Research at New Zealand Food Safety.

“The guidance reflects the increased diversity in the New Zealand diet. The update not only provides more options, but also ensures all risky foods are captured and provides simple ways to reduce the chance of illness from food,” she said.

“It’s important pregnant women know what’s safe to they can avoid dangerous infections, such as listeriosis and toxoplasmosis, which can affect them more severely than non-pregnant women.”

Dr McDonald said the key information for women include:

  • thoroughly cooking seed sprouts (such as alfalfa or mung bean) before eating.
  • thoroughly cooking dried herbs before eating.
  • avoiding unpasteurised fruit juices and non-alcoholic cider.
  • avoiding low-acid, soft, pasteurised cheeses like Brie, Camembert, blue cheeses, ricotta, mozzarella, and feta unless they’re cooked.
  • updating guidance on some pasteurised dairy products (i.e. following manufacturer’s labelling advice and “best before” dates, etc.).
  • freshly cooked fish, mussels, oysters, crayfish, scallops, etc., should be cooked thoroughly until piping hot and eaten while hot.
  • whole melons should be washed and dried before cutting.
  • frozen berries should be cooked thoroughly before eating.
  • no restrictions on number of servings per week for gemfish, oreo dories, orange roughy, ling and smooth oreo fish species (previous advice limited the number of servings per week to minimise mercury intake).

“We know more about food safety now than we did just a few a years ago and it’s important people educate themselves and take simple steps such as washing produce and cooking certain foods properly,” Dr McDonald said.

More information on food and pregnancy

New Zealand Food Safety’s updated food safety guidance for pregnant women – YouTube

Research – Preharvest Treatment Improves Tomato Food Safety

Technology Networks

cherry-tomato-pristine-variety

When vegetable farmers harvest crops, they often rely on postharvest washing to reduce any foodborne pathogens, but a new University of Georgia study shows promise in reducing these pathogens — as well as lowering labor costs — by applying sanitizers to produce while it is still in the fields.

Salmonella, Shiga toxin-producing E. coli and Listeria monocytogenes are major causes of foodborne diseases and of public health concern in the U.S. Tomato-associated salmonella outbreaks reported to the Centers for Disease Control and Prevention have increased in frequency and magnitude in recent years, and fresh produce accounted for 21% of E. coli outbreaks reported to the CDC over a 20-year span.

Initially researchers were going to study the use of a nonchlorine-based sanitizer made of two food additives approved by the U.S. Food and Drug Administration — levulinic acid and sodium dodecyl sulfate — as a postharvest wash solution. However, at the suggestion of a producer involved in the study — Bill Brim of Lewis Taylor Farms in Tifton, Georgia — they designed the study using the solution in a preharvest spray, said Tong Zhao, associate research scientist with the Center for Food Safety on the UGA Griffin campus.

While producers commonly use chlorine-based disinfectants — including chlorine gas, sodium hypochlorite, calcium hypochlorite and chlorine dioxide — to treat produce postharvest, the preharvest application of bactericides is not a common practice, Zhao said.

Cambodia – K-State researchers to work on team targeting foodborne illness in Cambodia

K State

Kansas State researchers received a $760,000 grant from the Feed the Future Innovation Lab for Food Safety to help protect against foodborne diseases and increase food safety awareness in Cambodia.

The team, composed of researchers from K-State, Pennsylvania State University, Purdue University and Cambodia, will focus on the vegetable chain in Cambodia to reduce the prevalence of foodborne pathogens.

Jessie Vipham, assistant professor in animal sciences and industry and principal investigator on the grant, sees the project as an opportunity to expand access to safe food for all.

“From my personal perspective, I view food safety and the right to have safe food as a basic human right,” Vipham said. “When you think about a lot of the diseases that are associated with foodborne disease, they’re largely preventable and we have a lot of the technology and science and understanding to prevent foodborne disease.”

The project will last three and a half years and be a team effort between the U.S. and Cambodian researchers.

“This is really a collective research project that is meant to be country led and focus on questions that Cambodians thought were important,” Vipham said. “We’ve been given an opportunity to collaborate and work in a team atmosphere on a project that will develop food safety systems for Cambodia with Cambodia as major project partners.”

Valentina Trinetta, assistant professor in food safety and microbiology and researcher on the grant, said increasing knowledge about food safety will help protect Cambodians from the harmful diseases.

“Food safety in developing countries is very much linked to food insecurity, so improving the education in those countries might help to educate and save a lot of children that are mainly affected by food insecurity,” Trinetta said. “That will help them not to be developing anymore, but to advance faster.”

Research – Source attributed case-control study of campylobacteriosis in New Zealand

IJID

Campylobacter kswfoodworld

Image CDC

Background

Following an initial reduction in human campylobacteriosis in New Zealand after the implementation of poultry food chain-focused interventions during 2006–2008, further decline has been relatively small.
We report a year-long study of notified campylobacteriosis cases, incorporating a case control study combined with a source attribution study. The purpose was to generate up-to-date evidence on the relative contributions of different sources of campylobacteriosis in New Zealand.

Methods

The study approach included: A case-control study of notified cases (aged six months or more) sampled in a major urban centre (Auckland, every second case) and a mixed urban/rural area (Manawatū/Whanganui, every case), between 12 March 2018 and 11 March 2019.
Source attribution of human campylobacteriosis cases sampled from these two regions over the study period by modelling of multilocus sequence typing data of Campylobacter jejuni and C. coli isolates from faecal samples of notified human cases and relevant sources (poultry, cattle, sheep).

Results

Most cases (84%) were infected with strains attributed to a poultry source, while 14% were attributed to a cattle source. Approximately 90% of urban campylobacteriosis cases were attributed to poultry sources, compared to almost 75% of rural cases.
Poultry consumption per se was not identified as a significant risk factor. However specific risk factors related to poultry meat preparation and consumption did result in statistically significantly elevated odds ratios.

Conclusions

The overall findings combining source attribution and analysis of specific risk factors indicate that poultry meat remains a dominant pathway for exposure and infection.

Research – Applying pressure to control Listeria

Meat poultry

The Centers for Disease Control and Prevention, Atlanta, is currently investigating a multistate outbreak of listeriosis that has resulted in one death and 10 people hospitalized. Listeriosis is a foodborne disease caused by Listeria monocytogenes, a pathogenic microorganism that is omnipresent in the environment. It is a facultative anaerobic bacterium capable of surviving in the presence or absence of oxygen. It can grow and reproduce inside the host’s cells and is one of the most virulent foodborne pathogens, with 20% to 30% of foodborne listeriosis infections in high-risk individuals being fatal.

Ready-to-eat (RTE) meats such as deli-style chicken, ham, pastrami, prosciutto, roast beef, salami and turkey are particularly vulnerable, as Listeria can live and thrive on plastic, metal and in water, too. While heat will kill this dangerous pathogen, RTE meats seldom undergo a sufficient heat treatment by consumers to destroy the bacteria.

There are a range of ingredients that may be included to assist with food safety; however, in efforts to keep labels as clean as possible, a growing number of meat processors are turning to high-pressure processing (HPP). This is a non-thermal treatment that renders packaged RTE meats free from pathogenic microorganisms. Companies such as Hormel Foods Corp., Austin, Minn., and its subsidiary, Applegate Farms, Bridgewater, NJ, use HPP on many RTE refrigerated meat and poultry products.

Research – Aspergillus-Derived Mycotoxins in the Feed and Food Chain

Frontiers in Microbiology

kswfoodworld

Image CDC

Aspergillus-produced mycotoxins can enter the feed and food chain at many points in both pre-harvest and post-harvest. Although current climate changes seem to speed up the world-wide spread of mycotoxigenic fungi including the Aspergilli and also facilitate the production of these harmful secondary metabolites the factors governing these disadvantageous global processes are only partly understood or even have remained completely hidden until now. This Research Topic summarizes our knowledge on Aspergillus-derived mycotoxins especially focusing on three major areas of on-going research: (i) toxicological, medical, veterinary aspects, prevalence, detection, risk assessment, control strategies, (ii) ecology and biological control of mycotoxigenic Aspergilli in the fields, and (iii) pre-harvest and post-harvest management of mycotoxigenic Aspergilli and their mycotoxin production. We hope that the wealth of information generously provided by the Aspergillus mycotoxin research community will help the hard work of all those experts, who are active in this important field, and the papers collected here will be instructive and illuminating readings for students and the public as well.

Research – Reducing Campylobacter jejuni, Enterobacteriaceae, Escherichia coli, and total aerobic bacteria on broiler carcasses using combined ultrasound and steam

Journal of Food Protection

Campylobacter kswfoodworld

Campylobacteriosis is the most frequently reported foodborne illness in Europe and many other parts of the world. Campylobacter can colonize the intestines of broilers, most often in large amounts. Broilers are usually slaughtered in a high-speed automated system that can rupture the intestines during evisceration, resulting in contamination of carcasses with intestinal bacteria such as Campylobacter. This study evaluated the combined effect of ultrasound and steam (SonoSteam®) on naturally contaminated chicken carcasses at a large-scale abattoir in Sweden. Ultrasound at 30-40 kHz and steam at 84-85 °C or 87-88 °C was used at slaughter with a line speed of 18 000 birds per hour. The amount of Campylobacter spp., Enterobacteriaceae , Escherichia coli , and total aerobic bacteria on neck skins from 103 chicken carcasses, sampled before and after treatment by SonoSteam, was analyzed.Campylobacter spp. was detected in 58 (56%) of the 103 neck skins, from birds belonging to four of the seven flocks represented. All 58 isolates were identified as Campylobacter jejuni . After the SonoSteam treatment, a mean reduction in C. jejuni, Enterobacteriaceae, E. coli and total aerobic bacteria were log 0.5 ± 0.8, log 0.6 ± 0.6, log 0.5 ± 0.6, log 0.4 ± 0.7 CFU/g respectively. No significant differences in reduction between the two different treatment temperatures was observed for any of the bacteria.Although the bacterial reductions were significant, large amounts of bacteria remained on the carcasses after treatment. Further studies are needed to identify optimal measures at slaughter to reduce food spoilage bacteria and pathogenic bacteria, which should be considered in a One Health perspective.

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

Journal of Food Protection

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.

Research – Characterization and Source Investigation of Multidrug-Resistant Salmonella Anatum from a Sustained Outbreak, Taiwan

CDC

kswfoodworld salmonella

Abstract

An ongoing outbreak of multidrug-resistant Salmonella enterica serovar Anatum began in Taiwan in 2015. Pork and poultry were identified as vehicles for transmission. Contaminated meat contributed to the high rate of infections among children. Nearly identical Salmonella Anatum strains have been identified in the United Kingdom, the United States, and the Philippines.

Nontyphoidal Salmonella (NTS) is a major cause for foodborne diseases worldwide. In Taiwan, the ambient climate and flourishing pig-raising industry makes NTS infections rampant. As in other countries, salmonellosis was primarily caused by Salmonella enterica serovars Enteritidis and Typhimurium in Taiwan (1), but rare serovars such as Salmonella Goldcoast have appeared in recent years (2). Recommended antimicrobial treatment options for salmonellosis include fluoroquinolones and extended-spectrum cephalosporins (1). However, resistance to these antibiotics has been emerging in many countries, leading to increased disease prevalence, disease severity, and death and the requirement of last-line antimicrobial drugs (e.g., carbapenems) (35).

Since 2015, northern Taiwan has seen an increase in Salmonella infections, caused by previously rare Salmonella Anatum. The infections were also reported in central Taiwan, indicating that this outbreak had already prevailed throughout the entire island (6). Co-resistance to ceftriaxone and ciprofloxacin are the main feature of the outbreak clone. Evidence from epidemiologic, laboratory, and supply-chain investigations identified raw pork and poultry as the vehicle for spread of this strain. More important, genomic comparisons against the global public database indicated that this clone has appeared in Europe, Asia, and America. Given the increasing globalization of foodstuffs, these findings prompt an urgent global sharing of whole-genome sequencing (WGS) data to facilitate disease surveillance and early recognition of international foodborne outbreaks (7,8).

Research – Quantification of cross-contamination of Campylobacter jejuni during food preparation in a model kitchen in China

Journal of Food Protection

campy2

Image CDC

Numerous outbreak investigations and case-control studies of campylobacteriosis have provided evidence that handling Campylobacter -contaminated chicken products is a high risk factor for infection and illness. In this study, the cross-contamination and transfer rates of Campylobacter jejuni from chicken to ready-to-eat foods were determined in various food-handling scenarios. Skinless raw chicken breasts were artificially contaminated with Campylobacter jejuni and diced on three kinds of texture cutting boards. Whether cold water or cold water with detergent or hot water was used, statistically significant differences were found between the transfer rate of Campylobacter jejuni to unwashed and washed cutting boards or hands, respectively. When both kitchen knife and cutting board were reused after dicing the artificially contaminated chicken, the transfer rates of Campylobacter jejuni to cucumber cut on bamboo, wooden and plastic cutting board were 16.28%, 12.82% and 5.32%, respectively. The transfer rates from chicken to bread, a large lift-up water faucet handle and a small twist faucet handle via unwashed hands were 0.49%, 4.64% and 3.14%, respectively. This research provides scientific evidence that various types of contaminated kitchen-ware and cook’s hand are vital potential vehicles for the cross-contamination of Campylobacter from raw chicken to ready-to-eat food, and emphasizes the importance of timely and properly cleaning to prevent cross-contamination during food handling, therefore a high quality consumer education to reduce the risk of foodborne infection is urgent and necessary.