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Food Microbiology Aug 2021Listeria monocytogenes is a foodborne pathogen that causes a life-threatening disease in humans known as listeriosis. Contamination of food during processing is the main... (Review)
Review
Listeria monocytogenes is a foodborne pathogen that causes a life-threatening disease in humans known as listeriosis. Contamination of food during processing is the main route of transmission of Listeria monocytogenes. Therefore, biocides play a crucial role in food processing environments as they act as the first line of defense in the prevention and control of L. monocytogenes. Residues of biocides may be present at sublethal concentrations after disinfection. This, unfortunately, subjects L. monocytogenes to selection pressure, giving rise to tolerant strains, which pose a threat to food safety and public health. This review will give a brief description of L. monocytogenes, the clinical manifestation, treatment of listeriosis as well as recently recorded outbreaks. The article will then discuss the current literature on the ability of L. monocytogenes strains to tolerate biocides especially quaternary ammonium compounds as well as the mechanisms of tolerance towards biocides including the activation of efflux pump systems.
Topics: Animals; Disinfectants; Disinfection; Drug Resistance, Bacterial; Food Handling; Food Safety; Humans; Listeria monocytogenes; Listeriosis
PubMed: 33653529
DOI: 10.1016/j.fm.2021.103758 -
Meat Science Nov 2020In this study we investigated the prevalence and location of Listeria monocytogenes and hygiene indicator bacteria on beef and pig carcasses. Carcasses were sampled...
In this study we investigated the prevalence and location of Listeria monocytogenes and hygiene indicator bacteria on beef and pig carcasses. Carcasses were sampled after slaughter and before cooling at eight and nine sites on the carcass, respectively. For each sample, detection and enumeration of Listeria was performed, as well as the enumeration of Total Aerobic Counts (TAC) and Enterobacteriaceae. The L. monocytogenes isolates were also typed to determine pulsotypes and clonal complexes (CC). L. monocytogenes was detected on 46% [95% CI: 35-56%] of beef and 22% [95% CI: 11-32%] of pig carcasses. Contamination levels at the different carcass sites differed considerably between beef and pigs. Genetic typing of strains suggests that carcass contamination originates from both incoming animals with transmission during slaughter practices as well as persistent (CC9) contamination from the slaughterhouse environment. These findings can be used to understand the complexity of introduction and persistence of this pathogen in slaughter facilities. Accurate correlation of L. monocytogenes presence proved unfeasible with any of the tested hygiene indicator bacteria.
Topics: Abattoirs; Animals; Belgium; Cattle; Colony Count, Microbial; Enterobacteriaceae; Food Contamination; Food Microbiology; Listeria monocytogenes; Red Meat; Swine
PubMed: 32544760
DOI: 10.1016/j.meatsci.2020.108177 -
Toxins Jun 2020is among the best-characterized intracellular pathogens. Its virulence factors, and the way they interfere with host cells to hijack host functions and promote the...
is among the best-characterized intracellular pathogens. Its virulence factors, and the way they interfere with host cells to hijack host functions and promote the establishment and dissemination of the infection, have been the focus of multiple studies over the last 30 years. During cellular infection, was shown to induce host DNA damage and delay the host cell cycle to its own benefit. However, whether the cell cycle stage would interfere with the capacity of to infect human cultured cell lines was never assessed. We found here that preferentially infects cultured cells in G2/M phases. Inside G2/M cells, the bacteria lead to an increase in the overall mitosis duration by delaying the mitotic exit. We showed that infection causes a sustained activation of the spindle assembly checkpoint, which we correlated with the increase in the percentage of misaligned chromosomes detected in infected cells. Moreover, we demonstrated that chromosome misalignment in -infected cells required the function of two virulence factors, ActA and InlC. Our findings show the pleiotropic role of virulence factors and their cooperative action in successfully establishing the cellular infection.
Topics: Bacterial Proteins; Caco-2 Cells; Chromosome Segregation; G2 Phase Cell Cycle Checkpoints; Host-Pathogen Interactions; Humans; Listeria monocytogenes; Listeriosis; M Phase Cell Cycle Checkpoints; Membrane Proteins; Mitosis; Virulence; Virulence Factors
PubMed: 32575670
DOI: 10.3390/toxins12060411 -
International Journal of Food... Jul 2018Like with all food microorganisms, many basic aspects of L. monocytogenes life are likely to be influenced by its interactions with bacteria living in close proximity.... (Review)
Review
Like with all food microorganisms, many basic aspects of L. monocytogenes life are likely to be influenced by its interactions with bacteria living in close proximity. This pathogenic bacterium is a major concern both for the food industry and health organizations since it is ubiquitous and able to withstand harsh environmental conditions. Due to the ubiquity of Listeria monocytogenes, various strains may contaminate foods at different stages of the supply chain. Consequently, simultaneous exposure of consumers to multiple strains is also possible. In this context even strain-to-strain interactions of L. monocytogenes play a significant role in fundamental processes for the life of the pathogen, such as growth or virulence, and subsequently compromise food safety, affect the evolution of a potential infection, or even introduce bias in the detection by classical enrichment techniques. This article summarizes the impact of microbial interactions on the growth and detection of L. monocytogenes primarily in foods and food-associated environments. Furthermore it provides an overview of L. monocytogenes virulence in the presence of other microorganisms.
Topics: Food Microbiology; Food-Processing Industry; Listeria monocytogenes; Listeriosis; Microbial Interactions; Virulence
PubMed: 29677551
DOI: 10.1016/j.ijfoodmicro.2018.04.011 -
Infection and Immunity Jun 2024Ethanolamine (EA) affects the colonization and pathogenicity of certain human bacterial pathogens in the gastrointestinal tract. However, EA can also affect the...
Ethanolamine (EA) affects the colonization and pathogenicity of certain human bacterial pathogens in the gastrointestinal tract. However, EA can also affect the intracellular survival and replication of host cell invasive bacteria such as (LMO) and serovar Typhimurium (. Typhimurium). The EA utilization () genes can be categorized as regulatory, enzymatic, or structural, and previous work in LMO showed that loss of genes encoding functions for the enzymatic breakdown of EA inhibited LMO intracellular replication. In this work, we sought to further characterize the role of EA utilization during LMO infection of host cells. Unlike what was previously observed for . Typhimurium, in LMO, an EA regulator mutant () was equally deficient in intracellular replication compared to an EA metabolism mutant () and this was consistent across Caco-2, RAW 264.7, and THP-1 cell lines. The structural genes encode proteins that self-assemble into bacterial microcompartments (BMCs) that encase the enzymes necessary for EA metabolism. For the first time, native EUT BMCs were fluorescently tagged, and EUT BMC formation was observed and . Interestingly, BMC formation was observed in bacteria infecting Caco-2 cells, but not the macrophage cell lines. Finally, the cellular immune response of Caco-2 cells to infection with mutants was examined, and it was discovered that and mutants similarly elevated the expression of inflammatory cytokines. In conclusion, EA sensing and utilization during LMO intracellular infection are important for optimal LMO replication and immune evasion but are not always concomitant with BMC formation. (LMO) is a bacterial pathogen that can cause severe disease in immunocompromised individuals when consumed in contaminated food. It can replicate inside of mammalian cells, escaping detection by the immune system. Therefore, understanding the features of this human pathogen that contribute to its infectiousness and intracellular lifestyle is important. In this work we demonstrate that genes encoding both regulators and enzymes of EA metabolism are important for optimal growth inside mammalian cells. Moreover, the formation of specialized compartments to enable EA metabolism were visualized by tagging with a fluorescent protein and found to form when LMO infects some mammalian cell types, but not others. Interestingly, the formation of the compartments was associated with features consistent with an early stage of the intracellular infection. By characterizing bacterial metabolic pathways that contribute to survival in host environments, we hope to positively impact knowledge and facilitate new treatment strategies.
Topics: Listeria monocytogenes; Listeriosis; Humans; Ethanolamine; Mice; Animals; RAW 264.7 Cells; Caco-2 Cells; THP-1 Cells; Bacterial Proteins; Macrophages
PubMed: 38752742
DOI: 10.1128/iai.00162-24 -
Toxins May 2020During infection, the foodborne bacterial pathogen dynamically influences the gene expression profile of host cells. Infection-induced transcriptional changes are a... (Review)
Review
During infection, the foodborne bacterial pathogen dynamically influences the gene expression profile of host cells. Infection-induced transcriptional changes are a typical feature of the host-response to bacteria and contribute to the activation of protective genes such as inflammatory cytokines. However, by using specialized virulence factors, bacterial pathogens can target signaling pathways, transcription factors, and epigenetic mechanisms to alter host gene expression, thereby reprogramming the response to infection. Therefore, the transcriptional profile that is established in the host is delicately balanced between antibacterial responses and pathogenesis, where any change in host gene expression might significantly influence the outcome of infection. In this review, we discuss the known transcriptional and epigenetic processes that are engaged during infection, the virulence factors that can remodel them, and the impact these processes have on the outcome of infection.
Topics: Animals; Cellular Reprogramming; Epigenesis, Genetic; Host-Pathogen Interactions; Humans; Inflammation Mediators; Listeria monocytogenes; Listeriosis; Signal Transduction; Transcription Factors; Transcription, Genetic; Virulence; Virulence Factors
PubMed: 32380645
DOI: 10.3390/toxins12050294 -
Food Microbiology Aug 2021Paneer is a fresh, soft ready-to-eat cheese that is susceptible to Listeria monocytogenes contamination, exemplified by product recalls in Australia, Canada, and the...
Paneer is a fresh, soft ready-to-eat cheese that is susceptible to Listeria monocytogenes contamination, exemplified by product recalls in Australia, Canada, and the USA. Previous research demonstrates that L. monocytogenes grows in paneer, however there are no paneer-specific predictive models that quantify the effect of environmental conditions on L. monocytogenes viability. This study measured the viability of a five-strain cocktail of L. monocytogenes in freshly prepared paneer incubated at 4-40 °C. Growth rates were fitted with the extended Ratkowsky square root model, with growth rates ranging from 0.014 to 0.352 log CFU/h. In comparison with published models, only the ComBase L. monocytogenes broth model acceptably predicted growth (B = 1.01, A = 1.12) versus the developed model. The influence of paneer pH (5.0-6.0) and storage temperature (41-45 °C) on L. monocytogenes growth at the upper temperature growth boundary was described using a logistic model. These models provide quantitative tools to improve the safety of paneer processing conditions, shelf-life estimation, food safety management plans, and risk assessment.
Topics: Cheese; Colony Count, Microbial; Food Storage; Hydrogen-Ion Concentration; Kinetics; Listeria monocytogenes; Microbial Viability; Models, Biological; Temperature
PubMed: 33653517
DOI: 10.1016/j.fm.2021.103738 -
Methods in Molecular Biology (Clifton,... 2021A plasmid preparation is a method used to extract and purify plasmid DNA. Methods developed to purify plasmid DNA from bacteria generally involve harvesting and alkaline...
A plasmid preparation is a method used to extract and purify plasmid DNA. Methods developed to purify plasmid DNA from bacteria generally involve harvesting and alkaline lysis of the bacteria, precipitation of chromosomal DNA and protein, followed by purification of the plasmid DNA. Here, we describe the mini-preparation of plasmid DNA by a rapid small-scale method, adapted for Listeria monocytogenes. The quality of plasmid DNA isolated using this method is sufficient for analytical purposes but may be upscaled for further downstream analysis. Electrophoretic separation of the resultant lysate allows conclusions to be made on the presence, number, copy number, and size of the plasmids in the analyzed bacterial strains.
Topics: DNA, Bacterial; Electrophoresis, Agar Gel; Humans; Listeria monocytogenes; Listeriosis; Plasmids
PubMed: 32975773
DOI: 10.1007/978-1-0716-0982-8_12 -
BMC Microbiology Jun 2019Ready-to-eat (RTE) vegetables have become increasingly popular along with the trend of moving towards a healthy lifestyle. However, RTE vegetables are at a higher risk...
BACKGROUND
Ready-to-eat (RTE) vegetables have become increasingly popular along with the trend of moving towards a healthy lifestyle. However, RTE vegetables are at a higher risk of containing pathogens, maybe owing to lack of rigorous sanitization procedures. To understand the prevalence and potential risk of Listeria monocytogenes in RTE vegetables, we investigated the contamination level and characteristics of L. monocytogenes isolated from fresh vegetables.
RESULTS
Twenty-three (5.49%) of the 419 vegetables samples were positive for L. monocytogenes. Phylogenetic group I.1 (1/2a-3a) and II.2 (1/2b-3b-7) strains were predominant in 30 isolates, which accounted for 33.3 and 50.0%, respectively. Multilocus sequence typing of the 30 isolates grouped them into nine sequence types (STs). The most common STs were ST87 (36.7%) and ST8 (26.7%). Virulence analysis showed that all 30 isolates harbored eight classical virulence genes, 10.0% isolates harbored the llsX gene (ST3 and ST1 strains), and 36.7% carried the ptsA gene and belonged to ST87. Approximately 83.3% isolates carried full-length inlA, whereas five isolates had premature stop codons in inlA, three of which belonged to ST9 and two to ST8. Antibiotic susceptibility showed the isolates were varyingly resistant to 13 antibiotics, 26.7% of the isolates were multi-drug resistant.
CONCLUSIONS
The fresh vegetables contain some potential hypervirulent L. monocytogenes (ST1 and ST87) in the Chinese markets. In addition, the high rate of L. monocytogenes isolates was multi-drug resistant. Fresh raw vegetables may be a possible transmission route for L. monocytogenes infection in consumers. Therefore, sanitization of raw fresh vegetables should be strengthened to ensure their microbiological safety when used as RTE vegetables.
Topics: Bacterial Proteins; Bacterial Typing Techniques; China; Codon, Terminator; Drug Resistance, Multiple, Bacterial; Food Microbiology; Listeria monocytogenes; Multilocus Sequence Typing; Phylogeny; Prevalence; Vegetables; Virulence Factors
PubMed: 31159734
DOI: 10.1186/s12866-019-1488-5 -
International Journal of Food... Aug 2021Listeria monocytogenes, a fatal foodborne pathogen has the extraordinary capacity to survive in harsh conditions and is a potential threat to public health. A novel...
Listeria monocytogenes, a fatal foodborne pathogen has the extraordinary capacity to survive in harsh conditions and is a potential threat to public health. A novel 91 kb plasmid pLM1686 was found in the prevalent L. monocytogenes sequence type (ST) 87 strain in China. In this study, the function and distribution of pLM1686 were firstly investigated in L. monocytogenes. The results showed plasmid pLM1686 had self-transmissible ability and existed in various types of L. monocytogenes isolates belonging to two lineages (lineage I and II), four serotypes (1/2b, 3b, 1/2c and 1/2a) and four STs (ST87, ST59, ST9 and ST120). The wild strain LM1686 and transconjugant strain 10403S exhibited significantly higher growth rate and biofilm formation in Modification of Welshimer's medium (MWB), greater salinity tolerance, stronger cell invasion and higher cytotoxicity than plasmid-cured strain and reference strain 10403S. Moreover, plasmid curing caused the loss of cadmium resistance of strain, and the recipient strain acquired cadmium resistance after conjugation. Thus, pLM1686 would provide L. monocytogenes advantages of surviving in adverse environments.
Topics: Adaptation, Physiological; China; Listeria monocytogenes; Plasmids; Serogroup
PubMed: 34116256
DOI: 10.1016/j.ijfoodmicro.2021.109261