Category Archives: microbial contamination

Research – Laboratory fishing expedition reels in a big catch: hidden pathogenic role of a housekeeping enzyme in Listeria

Purdue Edu

Purdue University doctoral student Dongqi Liu has identified a previously unknown strategy that the foodborne bacterium Listeria monocytogenes uses to invade and infect humans and animals.

Listeria is a huge problem in the food industry and for people who get infected,” said Arun Bhunia, a food microbiology professor in the Department of Food Science at Purdue. L. monocytogenes infects an estimated 1,600 each year in the U.S., resulting in about 260 deaths. At highest risk are pregnant women, unborn fetuses, immune-compromised and elderly people.

Bhunia’s previous research has shown that the Listeria adhesion protein (LAP) plays an important role in helping L. monocytogenes to pass through the gut barrier.

But a question lingered about the LAP. After the pathogen secretes LAP, the protein stays on the bacterium’s surface. How it does so remained a mystery. LAP must stay fastened to the bacterial surface for Listeria to cause infection.

Read the Link Above  to find out 🙂

Research – Prevalence and Characterisation of Clostridium perfringens Isolates in Food-Producing Animals in Romania



The aim of the current study was to investigate the prevalence of Clostridium perfringens (C. perfringens) recovered from animal faeces, as well as to determine the antimicrobial susceptibility of such isolates. A total of 14 (14/100; 14%) C. perfringens isolates were isolated from the 100 analysed samples (twelve recovered from faecal samples collected from pigs and two from veal calves’ faecal samples). The preponderant genotype was type A, with all isolates being cpa-positive. The most potent antimicrobial agents against C. perfringens proved to be vancomycin, rifampicin and lincomycin. A strong resistance to tetracycline (71.4%), penicillin (64.2%), erythromycin (42.8%) and enrofloxacin (35.7%) was also observed. To the best of our knowledge, this is the first analysis regarding the prevalence, characterization and antimicrobial susceptibility of C. perfringens in food-producing animals in Romania, adding further evidence for the probable role of animals as a source of resistant C. perfringens strains.

Research – Cronobacter Species in the Built Food Production Environment: A Review on Persistence, Pathogenicity, Regulation and Detection Methods



The powdered formula market is large and growing, with sales and manufacturing increasing by 120% between 2012 and 2021. With this growing market, there must come an increasing emphasis on maintaining a high standard of hygiene to ensure a safe product. In particular, Cronobacter species pose a risk to public health through their potential to cause severe illness in susceptible infants who consume contaminated powdered infant formula (PIF). Assessment of this risk is dependent on determining prevalence in PIF-producing factories, which can be challenging to measure with the heterogeneity observed in the design of built process facilities. There is also a potential risk of bacterial growth occurring during rehydration, given the observed persistence of Cronobacter in desiccated conditions. In addition, novel detection methods are emerging to effectively track and monitor Cronobacter species across the food chain. This review will explore the different vehicles that lead to Cronobacter species’ environmental persistence in the food production environment, as well as their pathogenicity, detection methods and the regulatory framework surrounding PIF manufacturing that ensures a safe product for the global consumer.

Research – Can Non-Toxigenic Vibrio cholerae Reduce a Cholera Infection?

CRIS Haifa


Vibrio cholerae, is the causative agent of cholera, that infects millions, annually. Chironomids are aquatic insects that host V. cholerae. Toxigenic strains produce cholera toxin (CT) which is the main virulence factor that causes cholera symptoms. In contrast to other bacterial pathogens, V. cholerae produces CT when at low cell densities while hemagglutinin/protease (HAP) is a high cell density-controlled gene. When V. cholerae behavior was examined on chironomids, we showed that high cell densities of non-toxigenic strains, increased HAP production in a toxigenic strain, conditions which could also potentially reduce CT production. Here we propose the value of studies that could support the potential of V. cholerae non-toxigenic strains to repress virulence gene expression in cholera-infected humans. High cell densities of a non-toxigenic strain present in an infected individual, may down-regulate CT expression, reducing cholera symptoms. To further test the hypothesis supported by a chironomid model, additional experiments in animal models are first needed.

Research – Microbiological Safety and Quality of Fermented Products


Fermented foods, which have emerged fortuitously over the course of human development, have become an essential part of human history worldwide. These rich and diverse fermented foods not only have unique flavors and qualities that appeal to local preferences but also embody local cultures and play a significant role in human life. Despite the popularity of fermented foods globally, many traditional fermented foods are still produced using open fermentation methods where it is difficult to evaluate the safety or function of microorganisms, leading to inevitable challenges. Therefore, to advance the knowledge on the functional properties of microorganisms in fermented foods globally, and shed light on the impact of these microorganisms on the safety and quality of fermented foods, we present “Microbiological Safety and Quality of Fermented Products”, a Special Issue publishing 10 papers.
This Special Issue covers four pivotal research topics. First, the microbial safety of fermented products, where researchers have focused on identifying food-borne pathogens in particular fermented products through detection methods, thereby improving the safety levels and reducing the harms of fermented products. Second, the functions of microorganisms in fermented foods have been investigated. Third, researchers have explored the application of microorganisms in various stages of fermented food production, for example, in pre-treatment, fermentation, and post-fermentation processes. Fourth, researchers have analyzed the changes in microflora during the different stages of fermenting food, providing crucial evidence for understanding the role played by microbes in creating distinctive flavor and quality.

Research – Food poisoning can be passed on through sex -Campylobacter

New Telegraph

Interesting headline as Campylobacter is not a food poisoning organism.

Researchers in the United States (U.S.) have found that Campylobacter infection, the most common foodborne illness in the Western world, can also be spread through sexual contact. To this end, the researchers from the University of Oklahoma had called on doctors to talk to their patients about risks associated with sexual contact amid a bout of food poisoning. Some Campylobacter species can infect humans, sometimes causing campylobacteriosis, a diarrhoeal disease in humans. While campylobacter infection was rarely serious, it can cause vomiting and diarrhoea, and can pose an additional risk for people with underlying health conditions. In the study, the team set out to understand whether Campylobacter infection can be spread through sexual contact. Dr. Katrin Kuhn, who led the study, said: “This research is important for public health messaging and for physicians as they talk to their patients about risks associated with sexual contact. “Although Campylobacter infection is usually not a serious disease, it causes diarrhoea, which can result in people missing work, losing productivity or perhaps losing their job.”

Research – Risk Factors for Non-O157 Shiga Toxin–Producing Escherichia coli Infections, United States



Shiga toxin–producing Escherichia coli (STEC) causes acute diarrheal illness. To determine risk factors for non-O157 STEC infection, we enrolled 939 patients and 2,464 healthy controls in a case–control study conducted in 10 US sites. The highest population-attributable fractions for domestically acquired infections were for eating lettuce (39%), tomatoes (21%), or at a fast-food restaurant (23%). Exposures with 10%–19% population attributable fractions included eating at a table service restaurant, eating watermelon, eating chicken, pork, beef, or iceberg lettuce prepared in a restaurant, eating exotic fruit, taking acid-reducing medication, and living or working on or visiting a farm. Significant exposures with high individual-level risk (odds ratio >10) among those >1 year of age who did not travel internationally were all from farm animal environments. To markedly decrease the number of STEC-related illnesses, prevention measures should focus on decreasing contamination of produce and improving the safety of foods prepared in restaurants.

Research – Study highlights two strategies used by Salmonella to escape the human body’s defenses

News Medical

Like thieves that constantly look for ways to evade capture, Salmonella enterica, a disease-causing bacterium, uses various tactics to escape the human body’s defense mechanisms. In a new study, researchers from the Department of Microbiology and Cell Biology (MCB), IISc, highlight two such strategies that the bacterium uses to protect itself, both driven by the same protein.

When Salmonella enters the human body, each bacterial cell resides within a bubble-like structure known as Salmonella-containing vacuole (SCV). In response to the bacterial infection, the immune cells in our body produce reactive oxygen species (ROS) and reactive nitrogen species (RNS), along with pathways triggered to break down these SCVs and fuse them with cellular bodies called lysosomes or autophagosomes, which destroy the bacteria. However, these bacteria have developed robust mechanisms to maintain vacuolar integrity, which is crucial for their survival. For example, when a bacterial cell divides, the vacuole surrounding it also divides, enabling every new bacterial cell to be ensconced in a vacuole. This also ensures that more vacuoles are present than the number of lysosomes which can digest them.

Research – UAE: Counts of E.coli in vegetables from retailers in Abu Dhabi and Dubai

Horti Daily

A new study by Ihab Habib, Rami H Al-Rifai, Mohamed-Yousif Ibrahim Mohamed, Akela Ghazawi, Afra Abdalla, Glindya Lakshmi, Neveen Agamy and Mushtaq Khan investigates the counts, antimicrobial resistance profile, and genome-based characterization of Escherichia coli in 11 different types of fresh salad vegetable products (n = 400) sampled from retailers in Abu Dhabi and Dubai in the United Arab Emirates.

E. coli was detected in 30% of the tested fresh salad vegetable items, with 26.5% of the samples having an unsatisfactory level (≥100 CFU/g) of E. coli, notably arugula and spinach. The study also assessed the effect of the variability in sample conditions on E. coli counts and found, based on negative binominal regression analysis, that samples from local produce had a significantly higher (p-value < 0.001) E. coli count than imported samples.

The analysis also indicated that fresh salad vegetables from the soil-less farming system (e.g., hydroponic and aeroponic) had significantly (p-value < 0.001) fewer E. coli than those from traditional produce farming. The study also examined the antimicrobial resistance in E. coli (n = 145) recovered from fresh salad vegetables and found that isolates exhibited the highest phenotypic resistance toward ampicillin (20.68%), tetracycline (20%), and trimethoprim-sulfamethoxazole (10.35%).

A total of 20 (13.79%) of the 145 E. coli isolates exhibited a multidrug-resistant phenotype, all from locally sourced leafy salad vegetables. The study further characterized 18 of the 20 multidrug-resistant E. coli isolates using whole-genome sequencing and found that the isolates had varying numbers of virulence-related genes, ranging from 8 to 25 per isolate. The frequently observed genes likely involved in extra-intestinal infection were CsgA, FimH, iss, and afaA. The β-lactamases gene blaCTX-M-15 was prevalent in 50% (9/18) of the E. coli isolates identified from leafy salad vegetable samples.

The study highlights the potential risk of foodborne illness and the likely spread of antimicrobial resistance and resistance genes associated with consuming leafy salad vegetables. It emphasizes the importance of proper food safety practices, including appropriate storage and handling of fresh produce.

Click here to access the entire research.

USA – Foodborne Illness Outbreaks at Retail Food Establishments — National Environmental Assessment Reporting System, 25 State and Local Health Departments, 2017–2019



Problem/Condition: Each year, state and local public health departments report hundreds of foodborne illness outbreaks associated with retail food establishments (e.g., restaurants or caterers) to CDC. Typically, investigations involve epidemiology, laboratory, and environmental health components. Health departments voluntarily report epidemiologic and laboratory data from their foodborne illness outbreak investigations to CDC through the National Outbreak Reporting System (NORS); however, minimal environmental health data from outbreak investigations are reported to NORS. This report summarizes environmental health data collected during outbreak investigations and reported to the National Environmental Assessment Reporting System (NEARS).

Period Covered: 2017–2019.

Description of System: In 2014, CDC launched NEARS to complement NORS surveillance and to use these data to enhance prevention efforts. State and local health departments voluntarily enter data from their foodborne illness outbreak investigations of retail food establishments into NEARS. These data include characteristics of foodborne illness outbreaks (e.g., etiologic agent and factors contributing to the outbreak), characteristics of establishments with outbreaks (e.g., number of meals served daily), and food safety policies in these establishments (e.g., ill worker policy requirements). NEARS is the only available data source that collects environmental characteristics of retail establishments with foodborne illness outbreaks.

Results: During 2017–2019, a total of 800 foodborne illness outbreaks associated with 875 retail food establishments were reported to NEARS by 25 state and local health departments. Among outbreaks with a confirmed or suspected agent (555 of 800 [69.4%]), the most common pathogens were norovirus and Salmonella, accounting for 47.0% and 18.6% of outbreaks, respectively. Contributing factors were identified in 62.5% of outbreaks. Approximately 40% of outbreaks with identified contributing factors had at least one reported factor associated with food contamination by an ill or infectious food worker. Investigators conducted an interview with an establishment manager in 679 (84.9%) outbreaks. Of the 725 managers interviewed, most (91.7%) said their establishment had a policy requiring food workers to notify their manager when they were ill, and 66.0% also said these policies were written. Only 23.0% said their policy listed all five illness symptoms workers needed to notify managers about (i.e., vomiting, diarrhea, jaundice, sore throat with fever, and lesion with pus). Most (85.5%) said that their establishment had a policy restricting or excluding ill workers from working, and 62.4% said these policies were written. Only 17.8% said their policy listed all five illness symptoms that would require restriction or exclusion from work. Only 16.1% of establishments with outbreaks had policies addressing all four components relating to ill or infectious workers (i.e., policy requires workers to notify a manager when they are ill, policy specifies all five illness symptoms workers need to notify managers about, policy restricts or excludes ill workers from working, and policy specifies all five illness symptoms requiring restriction or exclusion from work).

Interpretation: Norovirus was the most commonly identified cause of outbreaks reported to NEARS, and contamination of food by ill or infectious food workers contributed to approximately 40% of outbreaks with identified contributing factors. These findings are consistent with findings from other national outbreak data sets and highlight the role of ill workers in foodborne illness outbreaks. Although a majority of managers reported their establishment had an ill worker policy, often these policies were missing components intended to reduce foodborne illness risk. Contamination of food by ill or infectious food workers is an important cause of outbreaks; therefore, the content and enforcement of existing policies might need to be re-examined and refined.

Public Health Action: Retail food establishments can reduce viral foodborne illness outbreaks by protecting food from contamination through proper hand hygiene and excluding ill or infectious workers from working. Development and implementation of policies that prevent contamination of food by workers are important to foodborne outbreak reduction. NEARS data can help identify gaps in food safety policies and practices, particularly those concerning ill workers. Future analyses of stratified data linking specific outbreak agents and foods with outbreak contributing factors can help guide the development of effective prevention approaches by describing how establishments’ characteristics and food safety policies and practices relate to foodborne illness outbreaks.