Category Archives: Pathogen

Research – Inactivation Kinetics of Foodborne Pathogens in Carrot Juice by High-Pressure Processing

Posted on November 1, 2023 by | Leave a comment

MDPI

Abstract

In this study, Salmonella Typhimurium, Escherichia coli, and Listeria monocytogenes were separately inoculated in sterilized carrot juice and subjected to various types of high-pressure processing (HPP) at 200–600 MPa for 0.1–15 min to observe the effects of HPP on the inactivation kinetics of foodborne pathogens in carrot juice. The first-order model fits the destruction kinetics of high pressure on foodborne pathogens during the pressure hold period. An increase in pressure from 200 to 600 MPa decreased the decimal reduction time (D values) of S. Typhimurium, E. coli, and L. monocytogenes. Under pressure ≥ 400 MPa, the D values of E. coli were significantly higher than those of S. Typhimurium and L. monocytogenes, indicating that E. coli had greater resistance to high pressures than the others. The Zp values (the pressure range that causes the D values to change by 90%) of E. coli, S. Typhimurium, and L. monocytogenes were 195, 175, and 170 MPa, respectively. These results indicated that L. monocytogenes and E. coli were the most and least sensitive, respectively, to pressure changes. Additionally, the three bacteria were separately inoculated into thermal-sterilized carrot juice and subjected to 200–600 MPa HPP for 3 min. The treated carrot juices were stored at 4 °C for 27 d. Following S. Typhimurium and E. coli inoculation, the bacterial counts of the control and 200 MPa treatments remained the same during the storage duration. However, they decreased for the 300 and 400 MPa treatment groups with increasing storage duration. During the storage period, no bacterial growth was observed in the 500 and 600 MPa treatments. However, the bacterial number for the control and pressure treatment groups increased with prolonged storage duration following inoculation with L. monocytogenes. Therefore, following HPP, residual L. monocytogenes continued growing stably at low temperatures. Overall, HPP could inhibit and delay the growth of S. Typhimurium and E. coli in carrot juice during cold storage, but it was ineffective at inhibiting the growth of L. monocytogenes. There was a risk of foodborne illness despite the low-temperature storage of juice. The innovation of this preliminary study is to find the impact of high pressure on the inactivate kinetics of three food pathogens in carrot juice and its practical application in simulated contaminated juice.

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Posted in E.coli, Food Microbiology Research, Food Pathogen, Food Technology, HPP, Hurdle Technology, Listeria, Listeria monocytogenes, Pathogen, pathogenic, Research, Salmonella, Technology

Research Dry-surface foodborne pathogens under scrutiny at Purdue

Posted on October 28, 2023 by | Leave a comment

Purdue Edu

Maintaining sanitary conditions without using water presents special challenges

WEST LAFAYETTE, Ind. – During 2021 and 2022, national news reported on four infants being hospitalized and two dying after consuming infant formula tainted with Cronobacter sakazakii. The reports sparked the prolonged shutdown of a production plant that produced large quantities of the formula, leading to a monthslong nationwide shortage of infant formula.

The incident motivated Purdue University’s Haley Oliver to launch a project to improve the safety of low-moisture food-processing facilities. Oliver, a professor of food science, will collaborate with Old Dominion University’s Rishi Drolia on the project, which will target the C. sakazakii pathogen.

“It was a massive-scale food safety challenge that led to a food security challenge,” Oliver said.

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Posted in Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, microbial contamination, Microbial growth, Microbial Spoilage, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Pathogen, pathogenic

Research – Annual report concerning Foodborne Diseases in New Zealand 2022

Posted on October 20, 2023 by | Leave a comment

NZFS

Human health surveillance and its relationship to foodborne illness is essential for informing
the strategic direction that New Zealand Food Safety (NZFS) takes and regulatory measures
it puts in place to minimise foodborne illness in New Zealand and overseas consumers. The
annual ESR foodborne disease reports are critical, allowing NZFS to monitor trends in
foodborne illness in New Zealand by describing in a consistent manner evidence from case
notifications, case enquiries, outbreak investigations, and other epidemiological studies of
human enteric disease.
This report is the latest in a series providing a consistent source of data annually to monitor
trends in foodborne illness in New Zealand. The series can be found here.
When reading these reports, it is necessary to bear in mind that notified cases of illness
represent only a subset of all the cases that occur in New Zealand each year.
• Many sick individuals do not visit a GP or otherwise come to the attention of the
health system.
• Multiple factors (e.g., change in sensitivity of testing methods, proportion of human
faecal specimens being tested) affect the notification rates on top of any underlying
changes to disease incidence happening in New Zealand. Some cases notified in
New Zealand are due to exposure to a pathogen or toxin while they were overseas.
Most cases of foodborne diseases in New Zealand are sporadic, which makes attribution to a
source or event difficult. In contrast, outbreaks offer a better opportunity to identify the source
and most of the 271 outbreaks (253 cases) of potential foodborne disease in 2022 were
associated with commercial food operators and only five outbreaks in 2022 were associated
with food prepared in consumer’s homes. Despite robust investigation, some outbreaks
reported as “foodborne with an unidentified food source” could also be attributed to other
routes of transmission, such as water, animal contact, or person to person contact.
Listeriosis is perhaps the only disease fully attributable to consumption of contaminated food.
Campylobacteriosis, yersiniosis, infection by shiga toxin-producing E. coli (STEC), and
salmonellosis remain the predominant notified foodborne illnesses. Notification rates per
100,000 population are generally stable, being highest for very young children (0 to 4 years
age group) and for elderly people (70+ years)

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Posted in Campylobacter, food bourne outbreak, Food Illness, Food Microbiology Research, Food Pathogen, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Illness, outbreak, Pathogen, pathogenic, Research, STEC, STEC E.coli, Yersinia

Research – Comparison of Antibacterial Activity of Phytochemicals against Common Foodborne Pathogens and Potential for Selection of Resistance

Posted on October 8, 2023 by | Leave a comment

MDPI

Abstract

Antimicrobial resistance is now commonly observed in bacterial isolates from multiple settings, compromising the efficacy of current antimicrobial agents. Therefore, there is an urgent requirement for efficacious novel antimicrobials to be used as therapeutics, prophylactically or as preservatives. One promising source of novel antimicrobial chemicals is phytochemicals, which are secondary metabolites produced by plants for numerous purposes, including antimicrobial defence. In this report, we compare the bioactivity of a range of phytochemical compounds, testing their ability to directly inhibit growth or to potentiate other antimicrobials against Salmonella enterica Typhimurium, Pseudomonas aeruginosa, Listeria monocytogenes, and Staphylococcus aureus. We found that nine compounds displayed consistent bioactivity either as direct antimicrobials or as potentiators. Thymol at 0.5 mg/mL showed the greatest antimicrobial effect and significantly reduced the growth of all species, reducing viable cell populations by 66.8%, 43.2%, 29.5%, and 70.2% against S. enterica Typhimurium, S. aureus, P. aeruginosa, and L. monocytogenes, respectively. Selection of mutants with decreased susceptibility to thymol was possible for three of the pathogens, at a calculated rate of 3.77 × 10−8, and characterisation of S. enterica Typhimurium mutants showed a low-level MDR phenotype due to over-expression of the major efflux system AcrAB-TolC. These data show that phytochemicals can have strong antimicrobial activity, but emergence of resistance should be evaluated in any further development.

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Posted in Antibacterial, Antibiotic Resistance, antifungal, antimicrobial resistance, Antimicrobials, Drug Resistance, Food Microbiology Research, Food Pathogen, Pathogen, pathogenic, Research

Research – Evaluation of low-energy x-rays as an alternative to chlorine washing to control internalized foodborne pathogens in lettuce

Posted on September 30, 2023 by | Leave a comment

Wiley Online

Abstract

Low-energy X-rays can be used to reduce the number of pathogenic microorganisms in fresh produce, but the efficacy of this process against internalized bacteria in leafy greens has not yet been reported. The leaves of iceberg lettuce were cut into pieces and subjected to vacuum perfusion to force the foodborne pathogen cells into the intercellular spaces within the leaves. Sodium hypochlorite (200–400 ppm) washes were not effective in inactivating internalized bacterial cells from lettuce leaves. In contrast, treatment with 1.5 kGy low-energy X-rays reduced Escherichia coli O157: H7, Salmonella enterica Serovar Typhimurium, and Listeria monocytogenes levels by 6.89, 4.48, and 3.22 log CFU/g, respectively. Additionally, the maximum dose of X-rays did not adversely affect the color or texture of lettuce. These results suggest that low-energy X-ray treatment can be used to control internalized and surface-adhering pathogens in leafy vegetables without affecting product quality.

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Posted in Food Microbiology Research, Food Pathogen, Pathogen, pathogenic, Research

Research – Detection and Control of Foodborne Pathogens

Posted on September 26, 2023 by | Leave a comment

MDPI

The globalization of food trade and the emergence of disease outbreaks involving several foodborne pathogens and foods has focused the attention of both the research community and consumers on food safety. Microbial contamination can involve different stages of food processing and distribution, with a potentially dramatic impact on human health and food business. Several methods, involving culture-dependent and -independent techniques, were developed to detect foodborne pathogens in the food supply chain. In this respect, gold-standard reference methods are currently available for most pathogens, but some of them are time-consuming and expensive. Moreover, routine controls carried out by manufacturers and food safety authorities are normally focused on bacteria and not on viruses and fungi, which can have a significant impact on food safety. In the European Union, the number of human cases caused by Noroviruses and other Caliciviruses increased sharply in 2021 [1]. Therefore, based on the evidence given by an increasing amount of research, control strategies show a clear trend towards molecular techniques, such as polymerase chain reaction (PCR), multiplex PCR, real-time PCR (qPCR), reverse transcriptase PCR (RT-PCR), DNA microarrays, nucleic acid sequence-based amplification (NASBA), isothermal DNA amplification techniques, and next-generation sequencing (NGS) [2]. Moreover, to expand the knowledge on the behaviour of pathogens in food environments, proteome profiling and biosensors shed light on how these microorganisms interact and prevail in food systems [3].

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Posted in food bourne outbreak, Food Illness, Food Microbiology Research, Food Pathogen, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Illness, outbreak, Pathogen, pathogenic, Research

Research – A Comprehensive Review for the Surveillance of Human Pathogenic Microorganisms in Shellfish

Posted on September 2, 2023 by | Leave a comment

MDPI

Abstract

Bivalve molluscan shellfish have been consumed for centuries. Being filter feeders, they may bioaccumulate some microorganisms present in coastal water, either naturally or through the discharge of human or animal sewage. Despite regulations set up to avoid microbiological contamination in shellfish, human outbreaks still occur. After providing an overview showing their implication in disease, this review aims to highlight the diversity of the bacteria or enteric viruses detected in shellfish species, including emerging pathogens. After a critical discussion of the available methods and their limitations, we address the interest of technological developments using genomics to anticipate the emergence of pathogens. In the coming years, further research needs to be performed and methods need to be developed in order to design the future of surveillance and to help risk assessment studies, with the ultimate objective of protecting consumers and enhancing the microbial safety of bivalve molluscan shellfish as a healthy food.

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Posted in Amnesic Shellfish Poisoning, Decontamination Microbial, Diarrhoeic Shellfish Poisoning, Enteropathogenic E. coli, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, paralytic shellfish poisoning, Pathogen, pathogenic, Shellfish, shellfish toxin

Research – Trends in Food Pathogens Risk Attenuation

Posted on August 12, 2023 by | Leave a comment

MDPI

Abstract

Foodborne pathogens represent one of the most dangerous threats to public health along the food chain all over the world. Over time, many methods were studied for pathogen inhibition in food, such as the development of novel packaging materials with enhanced properties for microorganisms’ growth inhibition (coatings, films) and the use of emerging technologies, like ultrasound, radio frequency or microwave. The aim of this study was to evaluate the current trends in the food industry for pathogenic microorganisms’ inhibition and food preservation in two directions, namely technology used for food processing and novel packaging materials development. Five technologies were discussed in this study, namely high-voltage atmospheric cold plasma (HVACP), High-Pressure Processing (HPP), microwaves, radio frequency (RF) heating and ultrasound. These technologies proved to be efficient in the reduction of pathogenic microbial loads in different food products. Further, a series of studies were performed, related to novel packaging material development, by using a series of antimicrobial agents such as natural extracts, bacteriocins or antimicrobial nanoparticles. These materials proved to be efficient in the inhibition of a wide range of microorganisms, including Gram-negative and Gram-positive bacteria, fungi and yeasts.

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Posted in Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Pathogen, pathogenic

Research – Prevalence of Listeria monocytogenes in RTE Meat Products of Quevedo (Ecuador)

Posted on August 4, 2023 by | Leave a comment

MDPI

Abstract

Listeria monocytogenes is a foodborne pathogen that causes listeriosis and can be a problem in areas where meat products are sold at unregulated storage temperatures. In this work, the prevalence of L. monocytogenes was determined in the five most widely traded meat products in the province of Quevedo (Ecuador): bacon, “chorizo paisa”, grilled hamburger meat, mortadella, and salami. A total of 1000 samples of these products were analyzed in two seasons of the year (dry season/rainy season). All L. monocytogenes isolates were confirmed by PCR with primers designed for the iap gene. Furthermore, the positive samples were quantified for L. monocytogenes. Of the 1000 meat products analyzed, 163 were positive for L. monocytogenes (16.3%). The prevalence of L. monocytogenes in the two seasons in different meat products was as follows: 22.5% in mortadella, 19% in hamburger meat, 15% in bacon, 14.5% in chorizo paisa and 10.5% in salami. In addition, the concentration of L. monocytogenes in most of the positive samples was in the range of 4–6 log CFU/g or even higher. The results show the need for improvements in the hygienic measures and meat storage temperatures in Quevedo (Ecuador) to avoid risks of foodborne listeriosis.

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Posted in Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Pathogen, Listeria, Listeria monocytogenes, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Pathogen, pathogenic

Research – Inactivation of foodborne and other pathogenic bacteria with pyrrolidine based fatty acid amide derivatives

Posted on July 29, 2023 by | Leave a comment

Wiley Online

Abstract

Foodborne pathogens are a persistent threat to food and consumer safety. To mitigate outbreaks and contamination incited by these pathogens, the development of novel preventative safety controls and biorational inactivation measures are paramount. The objectives of this research were to evaluate the efficacy of pyrrolidine-based amide derivatives of decanoic (DEPY), lauric (LAPY), myristic (MYPY) and palmitic (PAPY) fatty acids for in-vitro inhibition and inactivation of various Gram-positive bacterial strains including Listeria monocytogenes (typically associated with foodborne illness), Bacillus subtilis, and Streptococcus mutans and Streptococcus sobrinus (both normally present in the oral cavity and involved with dental caries). Compared to no treatment (control), significant differences (P < 0.05) in the growth of Listeria strains were seen in-vitro with increased inhibition at higher amide concentrations (10,000–20,000 ppm). Furthermore, in-vitro growth inhibition of B. subtilis, S. sobrinus, and S. mutans was also observed with an effectiveness of LAPY>MYPY>PAPY>DEPY. In co-inoculation assays, LAPY treatment significantly reduced Listeria growth from 1.55 to >5.0 Log CFU/mL when a concentration range of 5 to 250 ppm was applied. Moreover, Listeria populations on pathogen-inoculated produce were significantly (P < 0.05) reduced from 0.51 to >3.00 Log CFU/g with greater inactivation on carrots compared to alfalfa, soybean, and pistachio. These results demonstrated the potential value of these FA amides against Gram-positive pathogenic bacteria. Biorational applications of antibacterial FA amides on fresh produce as a postharvest intervention process offers a great potential for enhancement of food safety.

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Posted in Bacillus, Bacillus Subtilis, Faecal Streptpcocci, Food Pathogen, Group B Streptococcus, Listeria, Pathogen, pathogenic