Category Archives: Research

Research – Outbreak of Shiga toxin-producing Escherichia coli O157 linked with consumption of a fast-food product containing imported cucumbers, United Kingdom, August 2020

Posted on April 27, 2021 by | Leave a comment

IJID Online

Background

In August 2020, an outbreak of Shiga toxin-producing Escherichia coli (STEC) O157:H7 occurred in the United Kingdom. Whole genome sequencing revealed these cases formed a genetically distinct cluster.

Methods

Hypotheses generated from case interviews were tested in analytical studies, and results informed environmental sampling and food chain analysis. A case-case study used non-outbreak ‘comparison’ STEC cases; a case-control study used a market research panel to recruit controls.

Results

A total of 36 cases were identified; all cases reported symptom onset between 3rd and 16th August 2020. The majority of cases (83%) resided in the Midlands region of England or Wales. A high proportion of cases reported eating out, with one fast-food restaurant chain mentioned by 64% (n = 23) of cases. Both case-case (adjusted odds ratio (aOR) 31.8, 95% confidence interval (CI) 1.6 – 624.9) and case-control (aOR 9.19, 95% CI 1.0 – 82.8) studies provided statistically significant results that consumption of a specific fast-food product was independently associated with infection.

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Posted in E.coli O157, E.coli O157:H7, food contamination, Food Hazard, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Poisoning, food recall, Food Safety, Food Safety Alert, Food Testing, Food Toxin, Research, STEC, STEC E.coli

Research – Survival of Salmonella and Shiga Toxin-producing Escherichia coli and Changes in Indigenous Microbiota During Fermentation of Kombucha Made from Home-brewing Kits

Posted on April 25, 2021 by | Leave a comment

Journal of Food Protection

Survival and growth of Salmonella and Shiga toxin-producing Escherichia coli (STEC) in kombucha prepared from four brands of commercially available kombucha kits intended for use by home brewers were investigated. Changes in microbiota responsible for fermentation were also determined. An initial population of Salmonella (6.77 log CFU/mL) decreased to below the detection limit (0.30 log CFU/mL) within 10 d in kombucha prepared from two of the four test brands. Populations of 1.85 and 1.20 log CFU/mL were detected in two brands fermented for 14 d. An initial population of STEC (7.02 log CFU/mL) decreased to <0.30 log CFU/mL in two of the four brands within 14 d; 0.20 and 0.87 log CFU/mL were detected in kombucha prepared from the other two brands. Salmonella and STEC increased in populations within 1 d in three brands of base tea used to prepare kombucha, and were stable throughout 14 d of incubation. Both pathogens steadily declined in base tea prepared from one brand of kombucha kit. Inactivation of the pathogens occurred as the pH of kombuchas decreased, but a clear correlation between rates of inactivation and decrease in pH was not evident when comparing kombuchas prepared from the four kits. Growth and peak populations of mesophilic aerobic microorganisms, yeasts, lactic acid bacteria, and acetic acid bacteria varied, depending on the kombucha kit brand. There was not strong evidence to correlate the behavior of Salmonella and STEC with any of these groups of indigenous microbiota. Results of this study show that the ability of Salmonella and STEC to survive in kombucha and base tea used to prepare kombucha is dependent on inherent differences in commercially available kombucha kits intended for use in home settings. Strict application of hygienic practices with the goal of preventing contamination with Salmonella or STEC is essential for reducing the risk of illness associated the consumption of kombucha.

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Posted in E.coli, E.coli O103, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbiological Risk Assessment, Microbiology, Research, Shigatoxin, STEC, STEC E.coli

Research – Histamine Control in Raw and Processed Tuna: A Rapid Tool Based on NIR Spectroscopy

Posted on April 25, 2021 by | Leave a comment

MDPI

The present study was designed to investigate whether near infrared (NIR) spectroscopy with minimal sample processing could be a suitable technique to rapidly measure histamine levels in raw and processed tuna fish. Calibration models based on orthogonal partial least square regression (OPLSR) were built to predict histamine in the range 10–1000 mg kg−1 using the 1000–2500 nm NIR spectra of artificially-contaminated fish. The two models were then validated using a new set of naturally contaminated samples in which histamine content was determined by conventional high-performance liquid chromatography (HPLC) analysis. As for calibration results, coefficient of determination (r2) > 0.98, root mean square of estimation (RMSEE) ≤ 5 mg kg−1 and root mean square of cross-validation (RMSECV) ≤ 6 mg kg−1 were achieved. Both models were optimal also in the validation stage, showing r2 values > 0.97, root mean square errors of prediction (RMSEP) ≤ 10 mg kg−1 and relative range error (RER) ≥ 25, with better results showed by the model for processed fish. The promising results achieved suggest NIR spectroscopy as an implemental analytical solution in fish industries and markets to effectively determine histamine amounts. View Full-Text

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Posted in Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, Histamine, microbial contamination, Microbiological Risk Assessment, Microbiology, Research, Technology

Research – Thermal Inactivation Kinetics of Salmonella and Enterococcus faecium NRRL-B2354 on whole chia seeds (Salvia hispanica L.)

Posted on April 24, 2021 by | Leave a comment

Journal of Food Protection

Intervention technologies for inactivating Salmonella in whole chia seeds are currently limited. The determination of the thermal inactivation kinetics of Salmonella o n chia seeds and selection of an appropriate nonpathogenic surrogate will provide a knowledge foundation for selecting and optimizing thermal pasteurization processes for chia seeds. In this study, chia seed samples from three separate production lots were inoculated with a five strain Salmonella cocktail or Enterococcus faecium NRRL-B2354 and equilibrated to 0.53 aw at room temperature (25 °C). After equilibration for at least three days, the inoculated seeds were subjected to isothermal treatments at 80, 85, or 90 °C. Samples were taken out at six timepoints and enumerated for survivors. Initial dilution of whole chia seeds was performed in a filter bag at a 1:30 ratio after it was shown to have similar recovery to grinding the seeds. Survivor data were fitted to consolidated models consisting of a primary model (log-linear or Weibull) and one secondary model (Bigelow). E. faecium exhibited higher thermal resistance than Salmonella , suggesting its suitability as a conservative nonpathogenic surrogate. The Weibull model was a better fit for the survivor data than the log-linear model for both bacteria due to its lower root mean square error and corrected Akaike’s Information Criterion values. Measurements of lipid oxidation and fatty acid content indicated a few statistically different values compared to the control samples, but the overall difference in magnitudes were relatively small. The thermal inactivation kinetics of Salmonella and E. faecium o n chia seeds as presented in this study can serve as a basis for developing thermal pasteurization processes for chia seeds.

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Posted in Enterococcus, Enterococcus faecium, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbiological Risk Assessment, Microbiology, Research, Salmonella, Salmonella Betel Leaves

Research – European Listeria typing exercise (ELiTE)

Posted on April 24, 2021 by | Leave a comment

Click to access European-listeria-typing-exercise-ELiTE-joint-report.pdf

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Posted in Food Microbiology Research, Listeria, Listeria monocytogenes, Research

Research – Norovirus Resistance

Posted on April 24, 2021 by | Leave a comment

Outbreak News Today

norovirus-1080x655

Clusters of a virus known to cause stomach flu are resistant to detergent and ultraviolet disinfection, according to new research co-led by Danmeng Shuai, Ph.D., an associate professor of civil and environmental engineering at the George Washington University and Nihal Altan-Bonnet, Ph.D., a senior investigator and the head of the Laboratory of Host-Pathogen Dynamics at the National Heart, Lung, and Blood Institute, part of the National Institutes of Health. The findings suggest the need to revisit current disinfection, sanitation and hygiene practices aimed at protecting people from noroviruses.

Noroviruses are the leading cause of gastroenteritis around the world, with over 21 million cases each year in the United States alone.

In 2018, Altan-Bonnet’s team found that noroviruses can be transmitted to humans via membrane-enclosed packets that contain more than one virus. In the past, scientists thought that viruses spread through exposure to individual virus particles, but the 2018 study–and others–showed how membrane-enclosed clusters arrive at a human cell and release an army of viruses all at once.

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Posted in Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Virus, microbial contamination, Norovirus, Research, UV Microbiology

Research – Relationship of growth conditions to desiccation tolerance of Salmonella enterica, Escherichia coli, and Listeria monocytogenes

Posted on April 24, 2021 by | Leave a comment

Journal of Food Protection

Growth on solid media as sessile cells is believed to increase the desiccation tolerance of Salmonella enterica . However, the reasons behind increased resistance have not been well explored. In addition, the same effect has not been examined for other foodborne pathogens such as pathogenic Escherichia coli or Listeria monocytogenes . The purpose of this research was two-fold: first, to determine the role of oxygenation during growth on the desiccation resistance of S. enterica , E. coli , and L. monocytogenes , and second, to determine the effect of sessile versus planktonic growth on the desiccation resistance of these pathogens. Three different serotypes each of Salmonella , E. coli , and L. monocytogenes were cultured in trypticase soy broth with 0.6% yeast extract (TSBYE), with (aerobic) shaking or on TSBYE with agar (TSAYE) under either aerobic or anaerobic conditions and harvested in stationary phase. After adding cell suspensions to cellulose filter disks, pathogen survival was determined by enumeration at 0 and after drying for 24 h. Results showed statistical differences in harvested initial populations prior to drying (0 h). For Salmonella , a correlation was found between high initial population and greater survival on desiccation (p = 0.05). In addition, statistical differences (p ≤ 0.05) between survival based on growth type were identified. However, differences found were not the same for the three pathogens, or between their serotypes. In general, Salmonella and E. coli desiccation resistance followed the pattern of aerobic agar media ≥ liquid media ≥ anaerobic agar media. For L. monocytogenes serotypes, resistance to desiccation was not statistically different based on mode of growth. These results indicate growth on solid media under aerobic conditions is not always necessary for optimal desiccation survival but may be beneficial when the desiccation resistance of the test serotype is unknown.

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Posted in E.coli, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Listeria monocytogenes, microbial contamination, Microbiological Risk Assessment, Microbiology, Research, Salmonella, Serotype

EU – EU gets stricter on black pepper from Brazil and peanuts from India

Posted on April 23, 2021 by | Leave a comment

Food Safety News

The European Commission has tightened checks on black pepper from Brazil because of Salmonella and peanuts from India because of aflatoxins.

These and other products entering the European Union from non-EU countries are now subject to a temporary increase of official controls. Revised legislation has also seen some checks become less strict.

The basis of the changes is the occurrence of incidents reported through the Rapid Alert System for Food and Feed (RASFF) and information from official controls performed by member states on food and feed of non-animal origin.

Tighter controls
The frequency of identity and physical checks on black pepper from Brazil has been increased from 20 percent to 50 percent. This is because of the large amount of non-compliances with EU requirements for Salmonella contamination detected during official controls in 2019 and early 2020 and the high number of reports in the RASFF during that period.

This year there have been 28 RASFF reports of Salmonella in black pepper from Brazil with most reported by Germany. Serotypes include Rubislaw, Infantis, Saintpaul, Coeln, Matadi, Gaminara, and Javiana.

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Posted in Aflatoxin, Food Microbiology Research, Food Toxin, Mold Toxin, Mould Toxin, Mycotoxin, Research, Salmonella, Salmonella in Black Pepper

Research – Antibacterial activity of sweet orange (Citrus sinensis) juice extract on selected bacteria

Posted on April 22, 2021 by | Leave a comment

AJMR

Plants have potentials to be developed into many new drugs yet to be discovered because of the countless chemical compositions in them. The investigation is targeted at the antibacterial activity of sweet orange juice extract on some bacteria using ethanol and ethyl ethanoate solvent to extract juice. Ditch method was used for the sensitivity testing against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Neisseria gonorrheae with a dilution factor of 10-10 for inoculation from pure culture of each selected bacteria. Disc method was used to test streptomycin, ciprofloxacin, gentamycin and penicillin G against test organisms as positive controls. There was no significant difference in the effect of different concentrations of the same extract on test organisms. However, there was a significant difference in the ethyl ethanoate and alcohol extracts. The ethyl ethanoate extract showed minimum inhibitory concentration at 300 mg/ml on E. coli (31.5 ± 0.5 mm); N. gonorrheae (21 ± 0.0 mm) at 200 mg/ml; S. aureus (22 ± 0.0 mm) and K. pneumoniae (37 ± 3.0 mm) at 100 mg/ml; while ethanol extract at 100 mg/ml on E. coli (23.5 ± 1.5 mm) and K. pneumoniae (25 ± 5.0 mm);  N. gonorrheae (13.5 ± 1.0 mm) and S. aureus (12.5 ± 2.5 mm) at 300 mg/ml and 200 mg/ml respectively. The zones of inhibition exhibited by streptomycin ranges from N. gonorrheae (14-24 mm) E. coli; ciprofloxacin varies from 15- 21 mm on K. pneumoniae and S. aureus respectively. Gentamycin ranges from 14-20 mm on N. gonorrheae and S. aureus respectively; and penicillin G on N. gonorrheae (14 mm) and S. aureus (28 mm). It can be concluded that sweet orange juice of ethyl ethanoate extract was more effective than the ethanol extract and the positive control.

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Posted in Antibacterial, E.coli, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Klebsiella, microbial contamination, Microbiological Risk Assessment, Microbiology, Research, Staphylococcus aureus

Research – Looking at edible insects from a food safety perspective

Posted on April 22, 2021 by | Leave a comment

FAO

While the subject of edible insects inherently encompasses a vast array of topics, from insect ecology to various rearing practices and processing methods, the primary objective of this publication is to provide an overview of the potential food safety issues associated with the production and consumption of insects . The farming of insects for food and feed is relatively recent and brings with it both benefits and challenges, some of which this publication explores .The regulatory frameworks that govern edible insects in various regions are discussed . In addition, the document highlights some of the other challenges, such as research gaps and scaling up production, that the insect sector will need to overcome if it is to have a more global reach . The intended audiences for this publication are food safety professionals, policymakers, researchers, insect producers, as well as consumers .

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Safety, microbial contamination, Microbiological Risk Assessment, Microbiology, Research