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Category Archives: Microbiology
Research – Microbial Load of Fresh Blueberries Harvested by Different Methods
Currently, more and more growers are transitioning to the use of over-the-row machine harvesters for harvesting fresh market blueberries. This study assessed the microbial load of fresh blueberries harvested by different methods. Samples (n = 336) of ‘Draper’ and ‘Liberty’ northern highbush blueberries, which were harvested using a conventional over-the-row machine harvester, a modified machine harvester prototype, ungloved but sanitized hands, and hands wearing sterile gloves were collected from a blueberry farm near Lynden, WA, in the Pacific Northwest at 9 am, 12 noon, and 3 pm on four different harvest days during the 2019 harvest season. Eight replicates of each sample were collected at each sampling point and evaluated for the populations of total aerobes (TA), total yeasts and molds (YM), and total coliforms (TC), as well as for the incidence of fecal coliforms and enterococci. The harvest method was a significant factor (p < 0.05) influencing the TA and TC counts, the harvest time was a significant factor influencing the YM counts, while the blueberry cultivar was an insignificant (p > 0.05) factor for all three indicator microorganisms. These results suggest that effective harvester cleaning methods should be developed to prevent fresh blueberry contamination by microorganisms. This research will likely benefit blueberry and other fresh fruit producers.
Posted in Coliforms, Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Mould/Mold, Moulds, TVC, Yeasts
Research – Nanoparticle Coatings on Glass Surfaces to Prevent Pseudomonas fluorescens AR 11 Biofilm Formation
Abstract
Microbial colonization of surfaces is a sanitary and industrial issue for many applications, leading to product contamination and human infections. When microorganisms closely interact with a surface, they start to produce an exo-polysaccaridic matrix to adhere to and protect themselves from adverse environmental conditions. This type of structure is called a biofilm. The aim of our work is to investigate novel technologies able to prevent biofilm formation by surface coatings. We coated glass surfaces with melanin-ZnO2, melanin-TiO2, and TiO2 hybrid nanoparticles. The functionalization was performed using cold plasma to activate glass-substrate-coated surfaces, that were characterized by performing water and soybean oil wetting tests. A quantitative characterization of the antibiofilm properties was done using Pseudomonas fluorescens AR 11 as a model organism. Biofilm morphologies were observed using confocal laser scanning microscopy and image analysis techniques were used to obtain quantitative morphological parameters. The results highlight the efficacy of the proposed surface coating to prevent biofilm formation. Melanin-TiO2 proved to be the most efficient among the particles investigated. Our results can be a valuable support for future implementation of the technique proposed here in an extended range of applications that may include further testing on other strains and other support materials.
Research – The Role of Biofilms in the Pathogenesis of Animal Bacterial Infections
Abstract
Biofilms are bacterial aggregates embedded in a self-produced, protective matrix. The biofilm lifestyle offers resilience to external threats such as the immune system, antimicrobials, and other treatments. It is therefore not surprising that biofilms have been observed to be present in a number of bacterial infections. This review describes biofilm-associated bacterial infections in most body systems of husbandry animals, including fish, as well as in sport and companion animals. The biofilms have been observed in the auditory, cardiovascular, central nervous, digestive, integumentary, reproductive, respiratory, urinary, and visual system. A number of potential roles that biofilms can play in disease pathogenesis are also described. Biofilms can induce or regulate local inflammation. For some bacterial species, biofilms appear to facilitate intracellular invasion. Biofilms can also obstruct the healing process by acting as a physical barrier. The long-term protection of bacteria in biofilms can contribute to chronic subclinical infections, Furthermore, a biofilm already present may be used by other pathogens to avoid elimination by the immune system. This review shows the importance of acknowledging the role of biofilms in animal bacterial infections, as this influences both diagnostic procedures and treatment.
Posted in Antibacterial, Antibiotic Resistance, antifungal, antimicrobial resistance, Antimicrobials, Biofilm, Decontamination Microbial, Food Micro Blog, Food Microbiology Blog, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk
Research IMPERATIVES FOR IMPROVEMENT OF FOOD SAFETY IN FRUIT AND VEGETABLE VALUE CHAINSIN VIET NAM
Key Findings
Production of fruits and vegetables in Viet Nam has been changing, which is driven by consumer preferences, urbanization, demographics, and rising incomes. Yet, they are produced with high usage of chemical fertilizers and pesticides. Consumers, in general, particularly in Ha Noi, buy most of their fruits and vegetables from traditional wet markets. Produce sold in these markets are not certified and not traceable to farms. Many wet markets in Ha Noi suffer from insu ̄cient infrastructure.
Waste management is unhygienic, and there is no clear separation between the areas selling fruits and vegetables and those selling animals and animal products.
Researchers from Vietnam National University of Agriculture (VNUA) collected biological samples of mustard greens, cucumber, and dragon fruit from farms, wholesale markets, and retail markets and analyzed them for Salmonella and Escherichia coli (E. coli) at the Department of Food Processing Technology at VNUA. Their analysis shows that foodborne pathogens are a particular concern for leafy vegetables. About 31% of the mustard greens samples collected from farms had E. coli loads above maximum permissible levels, 67% for samples collected from wholesale markets, and 82% from retail markets.
The increase of pathogenic loads across the value chains—from farm to retail—can be traced from lack of hygienic practices in handling of fruits and vegetables by all players.
Samples of dragon fruit, mustard greens, and cucumber were also analyzed for five commonly used chemical pesticides, two heavy metals, and nitrate. Pesticide residue analysis was performed at the National Institute for Food Control, while the other contaminants were analyzed at the Department of Food Processing Technology at VNUA.
Out the three types of produce sampled, pesticide residue above permissible levels was found only in cucumber. No samples had heavy metals and nitrate concentrations above maximum permissible levels. A banned active ingredient was detected in only one type of produce, mustard greens (in one of 20 samples), and was not found in dragon fruit or cucumber.
Chemical pesticide contamination in fruits and vegetables is a key concern of consumers and other stakeholders.
Foodborne pathogens are generally perceived as a smaller concern because consumers believe they can manage this risk through food preparation methods, which is a misconception as foodborne pathogens are the most important health risks for Vietnamese consumers (World Bank 2016 ).
The Government of Viet Nam has designated particular areas for “safe vegetable production.” These areas currently account for about 40% of Ha Noi’s vegetable area of 12,000 hectares. Vegetable farmers in these areas have been encouraged to form producer cooperatives. The government regularly tests soil and water quality and also tests vegetable produce for pesticide residues once a year. Livestock farming is not allowed in these areas to reduce the risk of cross-contamination.
These actions contribute to improving the food safety of vegetables to some extent. But they do help government agencies to better support smallholder vegetable farmers and monitor the quality of the produce.
Over the past decade, Viet Nam has revised its food safety laws and regulations, and the existing frameworks are mainly in line with international standards (Vu and Anh 2016 ). The country has a National Food Safety Committee, but there is no central food safety agency. Responsibilities are divided over three ministries (agriculture, commerce, and health), which results in some contradictions and confusion in enacting food safety-related regulations and acts among these ministries.
The implementing capacity of government organizations is rather limited. Authorities in charge of food safety seem to remain focused on inspection and control of end products, but not much on preventing contamination in production and marketing processes.
Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Safety, Food Safety Alert, Food Safety Management, Food Safety Regulations, food safety training, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Research
Ireland – Outbreak of Salmonella Typhimurium on the island of Ireland declared over
An outbreak investigation was launched by HPSC on 22/12/2022 after seven Salmonella Typhimurium isolates were identified as forming a cluster by routine Whole Genome Sequencing (WGS) carried out by the National Salmonella, Shigella and Listeria Reference Laboratory (NSSLRL). The isolates, which were of a less commonly occurring subtype of Salmonella Typhimurium, MLST type ST36, were related to two previous Salmonella Typhimurium isolates (sequenced in the NSSLRL in October 2020 and December 2021) and isolates identified in other European countries since 2020. The source of salmonellosis was not identified for these previous cases. An additional thirteen isolates were added to this cluster following further WGS by the NSSLRL in January 2023, while WGS performed by the Gastrointestinal Bacteria Reference Unit (GBRU) of the UK’s Health Security Agency’s (UKHSA) identified an additional seven cases resident in Northern Ireland and England that fell within the same cluster. In total 27 cases, identified between December 2022 and January 2023, who were resident on or who visited the island of Ireland were investigated as part of this outbreak.
Epidemiological data on outbreak cases were collected in each jurisdiction via national computerised surveillance systems, enhanced surveillance forms and trawling questionnaires. Symptom onset dates for cases ranged between the 30th of November 2022 and the 13th of January 2023, peaking on December 7th. Cases were geographically distributed across multiple areas on the island of Ireland. Fourteen cases were male and thirteen were female. Most cases were adults, ranging in age from 25 to 91 years, and two cases were children (aged <18 years). The median age of cases was 57 years. Forty-one percent (41%) of cases (n=11) were reported to have been hospitalised.[1]
A multi-disciplinary Outbreak Control Team (OCT), chaired by HPSC, was convened in January 2023. This group comprised representatives from HPSC, National Health Protection Service, NSSLRL, Departments of Public Health, the HSE Environmental Health Service, The Food Safety Authority of Ireland (FSAI) and the HSC Public Health Agency of Northern Ireland (PHA) and Food Standards Agency in Northern Ireland (FSA-NI). The OCT met four times during January and February 2023. Enhanced surveillance forms and trawling questionnaires were used to determine food and environmental exposure histories for all cases but no common exposures were identified. Additionally, food business supplier lists were examined and no commonalities were identified. The outbreak was declared over on February 16th 2023 as more than two incubation periods had elapsed without the reporting of new cases associated with this cluster but the source of this outbreak remains unknown.
In January 2023, FSAI instigated a food recall of batches of chicken products due to the detection of Salmonella Typhimurium and the Department of Agriculture, Food and the Marine launched an investigation into the incidence of Salmonella Typhimurium in a number of broiler flocks. There is no microbiological evidence of a link between the cases of salmonellosis investigated as part of this outbreak with the poultry product recall and positive poultry flocks.
Posted in Food Illness, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Illness, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, outbreak, Salmonella, Salmonella in Chicken
Research – Bacterial biofilm reduction by 275 and 455 nm light pulses emitted from light emitting diodes

Biofilm of antibiotic resistant bacteria. Rod-shaped and spherical bacteria. Escherichia coli, Pseudomonas, Mycobacterium tuberculosis, Klebsiella, Staphylococcus aureus, MRSA. 3D illustration
Abstract
Eradication of biofilms from the food contact surfaces is a challenging task, owing to their increased resistance to sanitizers and regular cleaning practices. The treatment with the light pulses emitted from the light emitting diode (LED) is an emerging surface decontamination technology, that can produce the antibiofilm effect by photodynamic inactivation. The objective of this study was to understand the antibiofilm efficacy of the 275 (Ultraviolet-C [UV-C]) and 455 nm (Blue) light pulses emitted from the LEDs against single and dual-species biofilms of Salmonella Typhimurium ATCC13311 and Aeromonas australiensis 03-09 on stainless steel (SS) coupons formed at different time. The biofilm formation by S. Typhimurium was improved when grown with A. australiensis in dual-species culture. Both 275 and 455 nm light pulses showed significant antibiofilm activity against S. Typhimurium and A. australiensis in single and dual-species biofilms. For instance, the 275 nm LED treatment of surfaces of SS coupons with 1.8 J/cm2 dose on each surface, produced reductions of 4.24 and 3.9 log (CFU/cm2) in single (cell attachment) and dual-species biofilms of S. Typhimurium, and reductions of 4.45 and 4.99 log (CFU/cm2) in single and dual-species biofilms of A. australiensis. However, the susceptibility of A. australiensis toward 455 nm LED treatments was influenced by the presence of S. Typhimurium in the dual-species biofilm. The confocal laser scanning microscopy images revealed significant cell membrane damage in the dual-species biofilms by the LED treatments with 275 and 455 nm light pulses. Overall, several factors like surface temperature increase, strains used, treatment dose, treatment time, and incubation period of biofilms influenced the inactivation efficacy of the 275 and 455 nm LED treatments against the biofilms formed on SS coupons. This study provides an insight into the inactivation efficacy of LED light pulses against bacterial biofilms on food grade SS surfaces.
Finland – Around 150 cases of food poisoning caused by oysters in Helsinki – Norovirus
Between February 8th and 26th, 2023, around 150 people have reported falling ill after eating oysters in restaurants across Helsinki. The illnesses are related to oysters imported from France and the Netherlands.
Reports of illnesses have been recorded from several different restaurants, prompting inspections and sample collections from affected venues. Importers of the oysters in question have also withdrawn their products from the market.
Those who have eaten oysters are being encouraged to contact environmental services to provide information for the ongoing investigation.
Posted in food bourne outbreak, Food Illness, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Illness, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Norovirus, Norovirus Oysters, outbreak
USA – FDA expands enoki mushrooms import alert from South Korea, adds China
On March 1, the FDA announced that it is expanding an import alert issued last July for all enoki mushrooms imported from the Republic of Korea to now also include enoki mushrooms from China for detention without a physical examination at U.S. borders (DWPE) to further protect public health.
Previously, this import alert only included enoki mushrooms from the Republic of Korea. From Oct. 2020 through Feb. 2023, state public health authorities conducted a sampling of enoki mushrooms from retail locations. Multiple state samples detected L. monocytogenes, which led to 18 recalls of enoki mushrooms in the U.S. since 2021. Eight of the recalls were linked to enoki mushrooms grown in the Republic of Korea, and 10 from China, were confirmed via labeling, traceback, or whole genome sequencing (WGS).
During this time, FDA sampled and analyzed 127 shipments of enoki mushrooms imported from China and found 18 to be violative, representing a violation rate of more than 14 percent. This effort identified 15 firms with violative products out of at least 37 declared firms that had exported enoki mushrooms from China to the U.S.
Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Listeria, Listeria Enoki Mushrooms, Listeria monocytogenes, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk
USA – New Hepatitis A outbreak discovered; other outbreak investigations continue
Federal officials have identified a new outbreak of hepatitis A infections suspected to be from a food source.
The Food and Drug Administration reports that it has begun product traceback efforts, but the agency has not named the product or products being traced.
As of March 1 there have been nine patients identified. The FDA has not reported where the patients live or their ages.
Hepatitis A can be transmitted when food handlers have contaminated hands. This contamination usually comes from microscopic amounts of feces. Thorough hand washing is one of the best ways to prevent transmission of the disease. Food surfaces can become contaminated as well as foods and beverages.
Posted in Food Illness, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Virus, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Hepatitis A, Illness, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, outbreak, Virus
USA – FDA Advises Restaurants, Retailers and Consumers to Avoid Recalled Wild Harvest Oysters from Harvest Area FL-3012, Cedar Key, Florida Potentially Contaminated with Salmonella
Audience
- Restaurants and food retailers that have received shipments of wild harvest oysters from harvest area FL-3012, Cedar Key, Florida, harvested between December 16, 2022, and February 24, 2023.
- Consumers who have recently purchased oysters from area FL-3012 sold in Alabama, Florida, and Georgia.
Product
- Wild harvest oysters from FL-3012, Cedar Key, Florida, harvested between December 16, 2022, and February 24, 2023. The oysters were distributed to restaurants and retailers in Alabama, Florida, and Georgia It is possible that additional states received these oysters through further distribution.
- Packaged oysters include harvest area information on the packaging.
Purpose
The FDA is advising consumers not to eat, and restaurants and food retailers not to sell, and to dispose of recalled wild harvest oysters from FL-3012, Cedar Key, Florida, harvested between December 16, 2022, and February 24, 2023, due to possible Salmonella contamination. These oysters were sold in Alabama, Florida, and Georgia. Consumers who purchased oysters after December 16, 2022, should check the packaging to see if they were wild harvest oysters from FL-3012, Cedar Key, Florida. Contaminated oysters can cause illness if eaten raw, particularly in people with compromised immune systems. Food contaminated with Salmonella may look, smell, and taste normal. Consumers of these products who are experiencing symptoms of salmonellosis should contact their healthcare provider, who should report their symptoms to their local Health Department.
Summary of Problem and Scope
The Florida Department of Health and the state health departments of Georgia and Alabama have detected a Salmonella outbreak associated with the consumption of raw oysters harvested from shellfish harvesting area FL-3012 in Cedar Key, Florida. To date, there have been 8 cases linked to this outbreak within Florida, Georgia, and Alabama. On February 24, 2023, the Florida Department of Agriculture and Consumer Services issued an emergency closure order for wild harvest oysters from harvest area FL-3012 and initiated a recallExternal Link Disclaimer of wild harvest oysters from harvest area FL-3012 in Cedar Key that were harvested from December 16, 2022, to February 24, 2023. On February 24, the State of Florida also notified the Interstate Shellfish Sanitation Conference of the closure and recall. Florida Department of Health posted an advisory bulletin on February 28. 2023.
FDA Actions
The FDA is issuing this alert advising consumers not to eat, and restaurants and food retailers not to sell, recalled wild harvest oysters from FL-3012, Cedar Key, Florida, harvested between December 16, and February 24, 2023, due to possible Salmonella contamination. The FDA will assist with and coordinate interstate notification efforts as necessary pending receipt of shellfish distribution information.
Symptoms of Salmonellosis
Most people infected with Salmonella will begin to develop symptoms 12 to 72 hours after infection. The illness, salmonellosis, usually lasts four to seven days and most people recover without treatment.
Most people with salmonellosis develop diarrhea, fever, and abdominal cramps. More severe cases of salmonellosis may include a high fever, aches, headaches, lethargy, a rash, blood in the urine or stool, and in some cases may become fatal. The U.S. Centers for Disease Control and Prevention estimated that approximately 450 persons in the United States die each year from acute salmonellosis.
Due to the range in severity of illness, people should consult their healthcare provider if they suspect that they have developed symptoms that resemble a Salmonella infection.
Recommendations for Restaurants and Retailers
Restaurants and retailers should not sell the potentially contaminated oysters. Restaurants and retailers should dispose of any potentially contaminated products by throwing them in the garbage or returning to their distributor for destruction.
Restaurants and retailers should also be aware that oysters and other filter-feeding bivalve molluscan shellfish may be a source of pathogens and should control the potential for cross-contamination of food processing equipment and the food processing environment. They should follow the steps below:
- Wash hands with warm water and soap following the cleaning and sanitation process.
- Retailers, restaurants, and other food service operators who have processed and packaged any potentially contaminated products need to be concerned about cross-contamination of cutting surfaces and utensils through contact with the potentially contaminated products.
- Retailers that have sold bulk product should clean and sanitize the containers used to hold the product.
- Regular frequent cleaning and sanitizing of food contact surfaces and utensils used in food preparation may help to minimize the likelihood of cross-contamination.
Posted in FDA, food bourne outbreak, Food Illness, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Illness, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, outbreak, Salmonella




