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Category Archives: Research
Research – Inhibitory Effects of Lactobionic Acid on Biofilm Formation and Virulence of Staphylococcus aureus
Staphylococcus aureus biofilm is a common bio-contaminant source that leads to food cross-contamination and foodborne disease outbreaks. Hence, there is a need for searching novel antibiofilm agents with potential anti-virulence properties to control S. aureus contamination and infections in food systems. In this study, the antibiofilm effects of lactobionic acid (LBA) against S. aureus and its influence on virulence were explored. The minimum inhibition concentration of LBA on S. aureus was 8 mg/mL. Viable count and crystal violet assays revealed that LBA inhibited and inactivated S. aureus biofilms. Microscopic observations further confirmed the antibiofilm activity of LBA on S. aureus that disrupted the biofilm architecture and inactivated the viable cells in biofilms. Moreover, LBA decreased the release of extracellular DNA (eDNA) and extracellular polysaccharide (EPS) in S. aureus biofilms. LBA suppressed biofilm formation by intervening metabolic activity and reduced virulence secretion by repressing the hemolytic activity of S. aureus. Furthermore, LBA altered the expressions of biofilm- and virulence-related genes in S. aureus, further confirming that LBA suppressed biofilm formation and reduced the virulence secretion of S. aureus. The results suggest that LBA might be useful in preventing and controlling biofilm formation and the virulence of S. aureus to ensure food safety.
Australia – Yersinia outbreak linked to milkshakes in Australia.
Scientists have found a contaminated ingredient used in milkshakes was likely to blame for a Yersinia outbreak in an Australian state.
In January 2023, an outbreak of Yersinia enterocolitica in residential aged care facilities was identified by the Gold Coast Public Health Unit and confirmed using whole genome sequencing.
There were 55 cases, including six staff. Sick residents ranged in age from 54 to 101 with a median of 87 years old. 41 females and 14 males were affected. Date of onset was known for 46 cases and ranged from Jan. 16 to Feb. 17, 2023, with a peak in late January. No cases went to the emergency department. One person, who was ill prior to Yersinia infection, died.
Research – New Zealand Food Safety on track to meet Campylobacteriosis-reduction target
New Zealand Food Safety is approaching its target to reduce rates of campylobacteriosis, the country’s most common foodborne illness, a new report published today has found.
Annual report concerning Foodborne Diseases in New Zealand 2023 [PDF, 5 MB]
The report, prepared for New Zealand Food Safety by the Institute for Environmental and Scientific Research (ESR), found that the rate of New Zealand-acquired foodborne illness caused by the bacteria Campylobacter has fallen from 88 to 77 cases per 100,000 population over the past 4 years.
“New Zealand Food Safety has made reducing campylobacteriosis rates a key priority, and we’ve made great strides in recent years,” says New Zealand Food Safety deputy director-general Vincent Arbuckle.
“Rates of infection more than halved between 2006 and 2020. In 2020 we set a target to reduce the rate by a further 20%, taking it to 70 cases per 100,000 by the end of 2024.
“These latest results show this goal is in sight, which is a testament to the combined and sustained work of government and industry over time.
“The Campylobacter Action Plan, put in place to help tackle the issue, mainly focuses on steps to reduce the levels of Campylobacter through the poultry food chain. We have worked with government, industry and NGOs right across the poultry food chain through the Campylobacter governance group with representatives from Ministry of Health, Poultry Industry Association of New Zealand, Foodstuffs North Island, Foodstuffs South Island, Woolworths NZ, and Consumer NZ.”
The poultry industry has continued to improve processing practices over time, resulting in a sustained reduction in the proportion of birds that have detectable levels of Campylobacter at the end of primary processing.
While changes in the food supply chain have achieved good results, consumer awareness remains an important part of the effort, Mr Arbuckle says.
“We know that about half of all foodborne illness is caused at home. These illnesses can be prevented with good food preparation techniques as well as proper cooking and storage.
“To support prevention of Campylobacter at home we run public education campaigns which focus on giving people information they can use to keep themselves safe.
“While it is rewarding to see campylobacteriosis rates falling, there is more work to do. The symptoms of campylobacteriosis can be unpleasant for healthy adults and the consequences for the very young and people over 65 can be serious.”
The report also provides data on other foodborne illnesses in New Zealand, including listeriosis, which remains steady with 37 cases notified this year, Mr Arbuckle said.
“Listeria is common in the environment and while case of illness are low, listeriosis can have tragic consequences, including death. Of the notified cases, 26 people were in the 60-plus age group, and 7 people died with listeriosis this year.
“There are a range of practical measures people can take at home to reduce their risk from Listeria. More information is available on our website.
Listeria infection: symptoms and advice
New Zealand Food Safety ran a Listeria education campaign in June targeting pregnant people and those aged over 60.
By the numbers:
- 76.8 campylobacteriosis cases per 100,000 population, with 4,010 cases domestically acquired
- 989 hospitalised with campylobacteriosis, with 325 in the over-70 age group – the highest number of hospitalisations across all age groups
- 37 cases of listeriosis, with 7 deaths. 26 of these cases occurred in people aged over 60.
Media release: Simple steps to avoid life-threatening listeriosis
Campylobacter infection: symptoms and advice
For further information and general enquiries, call MPI on 0800 00 83 33 or email info@mpi.govt.nz
For media enquiries, contact the media team on 029 894 0328.
Research – Monophasic variant of Salmonella Typhimurium 4,[5],12:i:- outbreak: an investigation by the Competent Authority – Italy in Roasted Pork
Italian Journal of Food Safety
Foodborne diseases represent a significant public health issue, regarding both collective health and the economy, with implications for healthcare costs and agribusiness. This paper shows the description and results of the investigation of a Salmonella enterica subsp. enterica foodborne outbreak that occurred in the Marche Region (Italy) in 2022, linked to the consumption of a roasted pork product (porchetta).
As part of the outbreak investigations discussed in this article, molecular analysis to evaluate the genomic correlation between clinical, food, and environmental origin strains was carried out. All Salmonella strains of different origins were serotyped as monophasic variants of Salmonella Typhimurium with an antibiotic-resistance pattern and an allelic profile such as to define the “cluster strain” allowing the correlation between clinical and food/environmental strains, definitively confirmed by whole genome sequencing analysis.
Following the laboratory evidence, corrective measures at the porchetta processing plant and at the retail stores involved were carried out by the Local Animal Based Food Hygiene Service. The results of this study show that effective intervention is only possible if efficient data exchange, standardized procedures, and staff training are guaranteed. The latter aspect also concerns the food business operator, who must take appropriate measures to minimize the risk.
Research – Salmonella Inactivation Model by UV-C Light Treatment in Chicken Breast
Abstract
This study aims to evaluate the effectiveness of inactivating Salmonella enteritidis in fresh chicken breast by irradiation using a combination of short-wave UV (0, 3, 6, 9, 12, and 15 J/cm2) and a natural antimicrobial such as caffeine (0, 5, 10, 15, and 20 nM/g) at 14 °C as alternative proposals to conventional techniques to reduce pathogens in food. The effect of temperature was studied in an initial phase (2 to 22 °C). The most suitable models were double Weibull in 60% of cases, with an adjustment of R2 0.9903–0.9553, and Weibull + tail in 46.67%, with an adjustment of R2 of 0.9998–0.9981. The most effective combination for the reduction in Salmonella was 12 J/cm2 of UV light and 15 nM/g of caffeine, with a reduction of 6 CFU/g and an inactivation rate of 0.72. The synergistic effect was observed by increasing caffeine and UV light. Furthermore, the physico-chemical characteristics of the food matrix were not affected by the combination of both technologies. Therefore, these results suggest that this combination can be used in the food industry to effectively inactivate Salmonella enteritidis without deteriorating product quality.
Research – Fungal Secondary Metabolites and Mycotoxins: Current Trends and Future Directions
Fungi are prolific producers of secondary metabolites, which are diverse bioactive compounds essential for their environmental interactions. Mycotoxins, a notable group of these metabolites, have significant toxic effects on humans, animals, and crops, posing global health and economic challenges. Recent scientific advances have enhanced our understanding of fungal secondary metabolites, enabling the discovery of new compounds with potential applications in drug development, agriculture, and biotechnology. Additionally, there is increasing recognition of the ecological roles of these metabolites, driving research into their use for sustainable agriculture, biocontrol, and environmental management. Interdisciplinary studies in mycology, chemistry, ecology, and biotechnology are vital for addressing the complexities of fungal secondary metabolites and mycotoxins. Currently, the study of these compounds is at a dynamic and transformative stage. By following current trends and exploring future directions, researchers can unlock new applications of fungal metabolites and solutions benefiting society and the environment.
Posted in Food Microbiology Research, Mycotoxin, Research
Research – Microbiological Quality and Antibiotic Resistance of Relevant Bacteria from Horsemeat
Abstract
The aim of this work was to assess the microbiological safety and quality of horsemeat. A total of 19 fresh horsemeat samples were analysed. Mesophile counts were 4.89 ± 1.08 log CFU/g, and Enterobacteriaceae, Staphylococcus spp., and enterococci were only isolated from 36.84%, 21.05%, and 15.79% of the samples, respectively. Neither Staphylococcus aureus nor Escherichia coli were found in any sample. Listeria spp. and Listeria monocytogenes were detected in 31.58% and 21.05% of the samples, respectively. Campylobacter jejuni was not detected in any sample. The dominant bacteria were lactic acid bacteria. Seven different Staphylococcus spp. were identified, the most common being S. delphini, S. saprophyticus, and S. warneri. S. delphini showed resistance against mupirocin and cefoxitin. All the L. monocytogenes strains showed resistance against ampicillin, cefotaxime, and oxacillin. Multi-resistant Yersinia enterocolitica, Stenotrophomonas maltophilia, and Vagococcus. fluvialis strains were found, with resistance to 11, 7, and 8 antibiotics, respectively, causing significant concern. Therefore, specific actions should be taken to decrease the contamination of horsemeat.
Research – Berry Pomace Extracts as a Natural Washing Aid to Mitigate Enterohaemorrhagic E. coli in Fresh Produce
Abstract
Enterohemorrhagic Escherichia coli (EHEC) outbreaks have been frequently linked to the consumption of produce. Furthermore, produce grown on organic farms possess a higher risk, as the farmers avoid antibiotics and chemicals. This study sets out to evaluate the effectiveness of advanced postharvest disinfection processes using berry pomace extracts (BPEs) in reducing EHEC load in two common leafy greens, spinach and lettuce. Spinach and lettuce were inoculated with ~5 log CFU/leaf EHEC EDL-933 and then treated with three different concentrations of BPE (1, 1.5, and 2 gallic acid equivalent, GAE mg/mL) for increasing periods of time. After the wash, the bacteria were quantified. Changes in the relative expression of virulence genes and the genes involved in cell division and replication and response against stress/antibiotics were studied. We observed a significant reduction in EHEC EDL933, ranging from 0.5 to 1.6 log CFU/spinach leaf (p < 0.05) washed with BPE water. A similar trend of reduction, ranging from 0.3 to 1.3 log CFU/mL, was observed in pre-inoculated lettuce washed with BPE water. We also quantified the remaining bacterial population in the residual treatment solutions and found the survived bacterial cells (~3 log CFU/mL) were low despite repeated washing with the same solution. In addition, we evaluated the phenolic concentration in leftover BPE, which did not change significantly, even after multiple uses. Alterations in gene expression levels were observed, with downregulation ranging from 1 to 3 log folds in the genes responsible for the adhesion and virulence of EHEC EDL933 and significant upregulation of genes responsible for survival against stress. All other genes were upregulated, ranging from 2 to 7 log folds, with a dose-dependent decrease in expression. This finding shows the potential of BPE to be used for sanitation of fresh produce as a natural and sustainable approach.
Posted in Bio-Preservative, EHEC, Food Microbiology Research, Research, STEC, STEC E.coli
Research – Response of Escherichia coli to Acid Stress: Mechanisms and Applications—A Narrative Review
Abstract
Change in pH in growth conditions is the primary stress for most neutralophilic bacteria, including model microorganism Escherichia coli. However, different survival capacities under acid stress in different bacteria are ubiquitous. Research on different acid-tolerance mechanisms in microorganisms is important for the field of combating harmful gut bacteria and promoting fermentation performance of industrial strains. Therefore, this study aimed to carry out a narrative review of acid-stress response mechanism of E. coli discovered so far, including six AR systems, cell membrane protection, and macromolecular repair. In addition, the application of acid-tolerant E. coli in industry was illustrated, such as production of industrial organic acid and developing bioprocessing for industrial wastes. Identifying these aspects will open the opportunity for discussing development aspects for subsequent research of acid-tolerant mechanisms and application in E. coli.
Posted in E.coli, Food Microbiology Research, Research
South Korea – Foodborne Illness on the Rise in South Korea
In 2023, South Korea experienced a significant increase in food poisoning cases compared to the previous three years during the COVID-19 pandemic. The country’s Ministry of Food and Drug Safety reported 359 cases affecting 8,789 patients, representing a 1.5-fold increase in cases and more than double the number of patients compared to the 2020 to 2022 average.
The analysis revealed a concentration of food poisoning incidents during the summer months, with 33.7% of cases occurring from July to September. Surprisingly, September saw the highest number of cases and patients, with 43 incidents affecting 1,590 individuals. July followed closely with 41 cases and 1,563 patients, while August recorded 37 cases with 977 patients.
