Category Archives: Pathogen

Research – Microbiology and Epidemiology of Escherichia albertii—An Emerging Elusive Foodborne Pathogen

Posted on April 22, 2022 by | Leave a comment

MDPI

Escherichia albertii, a close relative of E. coli, is an emerging zoonotic foodborne pathogen associated with watery diarrhea mainly in children and immunocompromised individuals. E. albertii was initially classified as eae-positive Hafnia alvei, however, as more genetic and biochemical information became available it was reassigned to its current novel taxonomy. Its infections are common under conditions of poor hygiene with confirmed transmission via contaminated water and food, mainly poultry-based products. This pathogen has been isolated from various domestic and wild animals, with most isolates being derived from birds, implying that birds among other wild animals might act as its reservoir. Due to the absence of standardized isolation and identification protocols, E. albertii can be misidentified as other Enterobacteriaceae. Exploiting phenotypes such as its inability to ferment rhamnose and xylose and PCR assays targeting E. albertii-specific genes such as the cytolethal distending toxin and the DNA-binding transcriptional activator of cysteine biosynthesis encoding genes can be used to accurately identify this pathogen. Several gaps exist in our knowledge of E. albertii and need to be bridged. A deeper understanding of E. albertii epidemiology and physiology is required to allow the development of effective measures to control its transmission and infections. Overall, current data suggest that E. albertii might play a more significant role in global infectious diarrhea cases than previously assumed and is often overlooked or misidentified. Therefore, simple, and efficient diagnostic tools that cover E. albertii biodiversity are required for effective isolation and identification of this elusive agent of diarrhea. View Full-Text

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Posted in E.albertii, E.coli, Enterobacteriaceae, Escherichia albertii, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Hafnia alvei, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Pathogen, pathogenic, Research, Zoonosis

Research – Bacterial inhibition of Fas-mediated killing promotes neuro-invasion and persistence -Listeria monocytogenes

Posted on April 12, 2022 by | Leave a comment

Nature.com

Infections of the central nervous system are among the most serious infections1,2, but the mechanisms by which pathogens access the brain remain poorly understood. The model microorganism Listeria monocytogenes (Lm) is a major foodborne pathogen that causes neurolisteriosis, one of the deadliest infections of the central nervous system3,4. Although immunosuppression is a well-established host risk factor for neurolisteriosis3,5, little is known about the bacterial factors that underlie the neuroinvasion of Lm. Here we develop a clinically relevant experimental model of neurolisteriosis, using hypervirulent neuroinvasive strains6 inoculated in a humanized mouse model of infection7, and we show that the bacterial surface protein InlB protects infected monocytes from Fas-mediated cell death by CD8+ T cells in a manner that depends on c-Met, PI3 kinase and FLIP. This blockade of specific anti-Lm cellular immune killing lengthens the lifespan of infected monocytes, and thereby favours the transfer of Lm from infected monocytes to the brain. The intracellular niche that is created by InlB-mediated cell-autonomous immune resistance also promotes Lm faecal shedding, which accounts for the selection of InlB as a core virulence gene of Lm. We have uncovered a specific mechanism by which a bacterial pathogen confers an increased lifespan to the cells it infects by rendering them resistant to cell-mediated immunity. This promotes the persistence of Lm within the host, its dissemination to the central nervous system and its transmission.

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Posted in food contamination, food handler, Food Hazard, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, food recall, Food Safety, Food Safety Alert, Listeria, Listeria monocytogenes, Pathogen, pathogenic, Research

Research – Zoonotic Pathogens in Wildlife Traded in Markets for Human Consumption, Laos

Posted on March 30, 2022 by | Leave a comment

CDC

Abstract

We tested animals from wildlife trade sites in Laos for the presence of zoonotic pathogens. Leptospira spp. were the most frequently detected infectious agents, found in 20.1% of animals. Rickettsia typhi and R. felis were also detected. These findings suggest a substantial risk for exposure through handling and consumption of wild animal meat.

Consumption of wildlife meat drives emerging infectious diseases , often amplified by human encroachment into natural areas and changes in land use. Wildlife trade and consumption have been responsible for outbreaks of diseases such as HIV-1 , Ebola , and monkeypox and possibly for the coronavirus disease pandemic . Wildlife markets bring diverse species into contact, usually in dense and unsanitary conditions, enabling mixing, amplification, and transmission of pathogens among species, including humans . Small mammals host diverse pathogenic bacteria and viruses , but little investigation of endemic bacteria transmission has occurred. Determining pathogens present in traded wildlife is vital to guide appropriate measures to combat zoonotic diseases and document societal and environmental costs of wildlife trade.

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

Research – Biofilm through the Looking Glass: A Microbial Food Safety Perspective

Posted on March 14, 2022 by | Leave a comment

MDPI

Food-processing facilities harbor a wide diversity of microorganisms that persist and interact in multispecies biofilms, which could provide an ecological niche for pathogens to better colonize and gain tolerance against sanitization. Biofilm formation by foodborne pathogens is a serious threat to food safety and public health. Biofilms are formed in an environment through synergistic interactions within the microbial community through mutual adaptive response to their long-term coexistence. Mixed-species biofilms are more tolerant to sanitizers than single-species biofilms or their planktonic equivalents. Hence, there is a need to explore how multispecies biofilms help in protecting the foodborne pathogen from common sanitizers and disseminate biofilm cells from hotspots and contaminate food products. This knowledge will help in designing microbial interventions to mitigate foodborne pathogens in the processing environment. As the global need for safe, high-quality, and nutritious food increases, it is vital to study foodborne pathogen behavior and engineer new interventions that safeguard food from contamination with pathogens. This review focuses on the potential food safety issues associated with biofilms in the food-processing environment. View Full-Text

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

Research – Distribution and Characteristics of Listeria spp. in Pigs and Pork Production Chains in Germany

Posted on March 6, 2022 by | Leave a comment

MDPI

Listeria (L.) monocytogenes is a foodborne pathogen that can cause disease, mainly in elderly, pregnant or immunocompromised persons through consumption of contaminated food, including pork products. It is widespread in the environment and can also be found in asymptomatic carrier animals, for example, in different tissues of pigs. To learn more about their nature, 16 Listeria spp. isolates found in tonsils and intestinal content of pigs and 13 isolates from the slaughterhouse environment were characterized using next-generation sequencing (NGS). A wide distribution of clonal complexes was observed in pigs, as well as in the pork production chain, suggesting multiple sources of entry. Hypervirulent clones were found in pig tonsils, showing the potential risk of pigs as source of isolates causing human disease. The presence of closely related isolates along the production chain suggests a cross-contamination in the slaughterhouse or recontamination from the same source, strengthening the importance of efficient cleaning and disinfection procedures. The phenotypical antimicrobial resistance status of L. monocytogenes isolates was examined via broth microdilution and revealed a low resistance level. Nevertheless, genotypical resistance data suggested multiple resistances in some non-pathogenic L. innocua isolates from pig samples, which might pose a risk of spreading resistances to pathogenic species. View Full-Text

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Posted in antimicrobial resistance, Antimicrobials, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Listeria, Listeria monocytogenes, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Pathogen, pathogenic, Research

Research – Genetic Diversity and Relationships of Listeria monocytogenes Serogroup IIa Isolated in Poland

Posted on March 5, 2022 by | Leave a comment

MDPI

In the present study, 100 L. monocytogenes isolates of serogroup IIa from food and food production environments in Poland were characterized towards the presence of virulence, resistance, and stress response genes using whole-genome sequencing (WGS). The strains were also molecularly typed and compared with multi-locus sequence typing (MLST) and core genome MLST analyses. The present isolates were grouped into 6 sublineages (SLs), with the most prevalent SL155 (33 isolates), SL121 (32 isolates), and SL8 (28 isolates) and classified into six clonal complexes, with the most prevalent CC155 (33 strains), CC121 (32 isolates), and CC8 (28 strains). Furthermore, the strains were grouped to eight sequence types, with the most prevalent ST155 (33 strains), ST121 (30 isolates), and ST8 (28; strains) followed by 60 cgMLST types (CTs). WGS data showed the presence of several virulence genes or putative molecular markers playing a role in pathogenesis of listeriosis and involved in survival of L. monocytogenes in adverse environmental conditions. Some of the present strains were molecularly closely related to L. monocytogenes previously isolated in Poland. The results of the study showed that food and food production environments may be a source of L. monocytogenes of serogroup IIa with pathogenic potential.

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

Research – Antimicrobial Activity of Ohelo Berry (Vaccinium calycinum) Juice against Listeria monocytogenes and Its Potential for Milk Preservation

Posted on March 3, 2022 by | Leave a comment

MDPI

Listeria monocytogenes is a foodborne pathogen and causes illnesses with a high mortality rate in susceptible populations. Several dairy-related outbreaks have been attributed to contamination by L. monocytogenes, which requires antimicrobial interventions to enhance the safety of these products. This study aimed to determine the antimicrobial activity of the ohelo berry (Vaccinium calycinum), a Hawaiian wild relative of cranberry, against L. monocytogenes in culture media and milk products. The effect of ohelo berry juice at its sub-inhibitory concentrations on the physicochemical properties, biofilm formation, and gene expression of L. monocytogenes was also investigated. The minimum inhibitory concentration of ohelo berry juice against L. monocytogenes was 12.5%. The sub-inhibitory concentration of ohelo berry juice (6.25%) significantly increased the auto-aggregation and decreased the hydrophobicity, swimming motility, swarming motility, and biofilm formation capability of L. monocytogenes. The relative expression of genes for motility (flaA), biofilm formation and disinfectant resistance (sigB), invasion (iap), listeriolysin (hly), and phospholipase (plcA) was significantly downregulated in L. monocytogenes treated by the 6.25% juice. L. monocytogenes was significantly inhibited in whole and skim milk supplemented with 50% ohelo berry juice, regardless of the fat content. These findings highlight the potential of ohelo berry as a natural preservative and functional food to prevent L. monocytogenes infection.

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Posted in Biofilm, Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Listeria, Listeria monocytogenes, Listeriolysin, microbial contamination, Microbiological Risk Assessment, Microbiology, Pathogen, pathogenic, Research

Research – Shiga Toxin-Producing Escherichia coli and Milk Fat Globules

Posted on February 27, 2022 by | Leave a comment

MDPI

Shiga toxin-producing Escherichia coli (STEC) are zoonotic Gram-negative bacteria. While raw milk cheese consumption is healthful, contamination with pathogens such as STEC can occur due to poor hygiene practices at the farm level. STEC infections cause mild to serious symptoms in humans. The raw milk cheese-making process concentrates certain milk macromolecules such as proteins and milk fat globules (MFGs), allowing the intrinsic beneficial and pathogenic microflora to continue to thrive. MFGs are surrounded by a biological membrane, the milk fat globule membrane (MFGM), which has a globally positive health effect, including inhibition of pathogen adhesion. In this review, we provide an update on the adhesion between STEC and raw MFGs and highlight the consequences of this interaction in terms of food safety, pathogen detection, and therapeutic development. View Full-Text

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Posted in Decontamination Microbial, Enteropathogenic E. coli, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Pathogen, pathogenic, Research, Shigatoxin, STEC, STEC E.coli

Research – The Efficacy of Conventional Spray, Electrostatic Spray, and Dip with a Combination of Hydrogen Peroxide and Peroxyacetic Acid to Inactivate Listeria monocytogenes on Apples

Posted on February 23, 2022 by | Leave a comment

Journal of Food Protection

This study aimed to evaluate the efficacy of a and hydrogen peroxide (H 2 O 2 ) and peroxyacetic-acid (PAA) mixer delivered by conventional garden sprayer (GS), electrostatic sprayer (ES) and dip methods to inactivate Listeria monocytogenes on apples. Organic Honey Crisp ( HC ), Fuji ( FJ ), and Pink Lady ( PL ) were dip-inoculated with Listeria monocytogenes (2-strain, serotype 1/2b), which were then kept untreated (control), sprayed with water only, or treated with the H 2 O 2 -PAA mixer (0.0064, 0.1, 0.25 and 0.50%) for 20 s via GS, ES, or dip, followed by draining (2 min) on aluminum foil. Surviving bacteria were recovered on Modified Oxford agar. Atomic force microcopy was used to detect the structural changes of inactivation of L. monocytogenes in broth medium by the H 2 O 2 -PAA mixer solution. Data (2 replicates/6 samples/replicate) were analyzed using the Mixed Model Procedure of SAS ( P =0.05). Initial counts of L. monocytogenes on untreated apples were 6.80 to 6.90 log CFU/apple. The dip method was the most effective treatment (P<0.05) on pathogen reductions (2.31-2.41 log CFU/apple) followed by GS (1.44-1.70 log CFU/apple) and then ES (0.84-1.20 log CFU/apples). Reductions of L. monocytogenes were greatest ( P < 0.05) when apples were treated with H 2 O 2 -PAA mixer -0.25 and -0.50%. Atomic force microscopy analyses indicated that inactivation of L. monocytogenes cells in H2O2-PAA mixer solutions resulted from disruption of the outer membrane. The H 2 O 2 -PAA mixer treated cells had increased width, height and decreased roughness when compared to the untreated cells. Results suggested that applying a H 2 O 2 -PAA mixer by dip or GS methods is better for pathogen reduction than ES on apples.

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

Research – Spain – Report of the Scientific Committee of the Spanish Agency for Food Safety and Nutrition (AESAN) on the safety of foods air-dried outdoors that are produced by traditional methods and which require an adjustment of the hygiene requirements that must be fulfilled

Posted on February 13, 2022 by | Leave a comment

AESAN

Abstract
The European Union recognises that traditional methods of food production are a valuable and irreplaceable heritage that must be preserved over time. Therefore, Regulation (EC) No. 852/2004 permits a degree of flexibility in its application provided food hygiene goals are not compromised. For decades, both plant and animal-based foods have been produced in Spain which are air-dried outdoors until reaching a low water activity (aw) that enables their preservation at room temperature. These foods include, raisins, dried apricots, dried figs, ñora peppers, dried fish or octopus that are at least partially air-dried, among others.
The Scientific Committee of the Spanish Agency for Food Safety and Nutrition (AESAN) is of the opinion that the processing of naturally dried foods leads to their correct preservation, provided they reach an aw that inhibits the proliferation of pathogenic microorganisms and the production of toxins in them. Some of the stages in the process may cause microbial inactivation.
Above all, it is necessary to ensure the absence of the formation of toxins, with aflatoxins being the ones that have been most frequently identified. Thus, it is considered that the drying should be conducted in the least time possible, ensuring a decrease of aw within the first 2-3 days of below 0.90 to inhibit the development of aflatoxins, and this drying should be continued until aw levels lower than 0.70 are reached, preventing the growth of pathogenic microorganisms that cause spoilage. It is necessary to guarantee suitable hygienic conditions during processing in order to prevent contamination by pathogens and/or toxins.
Although they cannot proliferate in the stated preservation conditions, they can remain viable in the final product, therefore they may pose a risk to consumer health. Microorganisms with a low infective dose and those that have been identified in dried products (such as S. aureus and Salmonella) and microbial toxins are especially relevant. Autonomous Communities must monitor compliance with the requirements to ensure that they do not pose a risk in these products.
Although these types of products have a low aw, within the range of 0.6 to 0.8 according to avail-able literature, given that this information is not available for each assessed product, the level of safety reached cannot be established on an individual basis. Additionally, the diverse factors used in some of them (additives and preservatives, pasteurisation processes, etc.) require individual assessment once all the necessary information is available. Therefore, the drying must reach aw levels below 0.70 in the least time possible for these types of products to be considered stable, as given these conditions, there is no scientific evidence that shows that the safety and stability of the dried products are compromised, provided good hygiene practices are maintained during their preservation and storage.
For final levels of aw that are higher, correct preservation may be achieved through a combination of factors which proves that it is effective throughout the shelf life of the product, maintaining the aforementioned appropriate hygiene practices.

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Posted in Aflatoxin, Available Water, aW, Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Pathogen, pathogenic, Research, Salmonella, Staphylococcus aureus, water activity