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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 -
Methods in Molecular Biology (Clifton,... 2021For assessing isolates of Listeria monocytogenes, serotype designation is the first subtyping method used. Methodologies used to assign serotype are currently evolving...
For assessing isolates of Listeria monocytogenes, serotype designation is the first subtyping method used. Methodologies used to assign serotype are currently evolving and will eventually be replaced with whole genome sequencing. Traditionally, serotyping has been done with agglutination reactions; however, alternative methods utilizing enzyme linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) are common. Described here are the three non-genomic methods and the advantages and disadvantages of each.
Topics: Agglutination Tests; Enzyme-Linked Immunosorbent Assay; Humans; Listeria monocytogenes; Listeriosis; Polymerase Chain Reaction; Serotyping
PubMed: 32975766
DOI: 10.1007/978-1-0716-0982-8_5 -
Food Microbiology Dec 2017Listeria monocytogenes can cause listeriosis, a severe foodborne disease. In Brazil, despite very few reported cases of listeriosis, the pathogen has been repeatedly...
Listeria monocytogenes can cause listeriosis, a severe foodborne disease. In Brazil, despite very few reported cases of listeriosis, the pathogen has been repeatedly isolated from dairies. This has led the government to implement specific legislation to reduce the hazard. Here, we determined the incidence of L. monocytogenes in five dairies and retail products in the Southeast and Midwest regions of Brazil over eight months. Of 437 samples, three samples (0.7%) from retail and only one sample (0.2%) from the dairies were positive for L. monocytogenes. Thus, the contamination rate was significantly reduced as compared to previous studies. MultiLocus Sequence Typing (MLST) was used to determine if contamination was caused by new or persistent clones leading to the first MLST profile of L. monocytogenes from the Brazilian dairy industry. The processing environment isolate is of concern being a sequence-type (ST) 2, belonging to the lineage I responsible for the majority of listeriosis outbreaks. Also, ST3 and ST8 found in commercialized cheese have previously been reported in outbreaks. Despite the lower incidence, dairy products still pose a potential health risk and the occurrence of L. monocytogenes in dairies and retail products emphasize the need for continuous surveillance of this pathogen in the Brazilian dairy industry.
Topics: Animals; Biodiversity; Brazil; Cattle; Dairy Products; Dairying; Food Contamination; Incidence; Listeria monocytogenes; Listeriosis; Multilocus Sequence Typing
PubMed: 28800821
DOI: 10.1016/j.fm.2017.06.012 -
Methods in Molecular Biology (Clifton,... 2021Listeria monocytogenes is a major food-borne pathogen and causative agent of a fatal disease, listeriosis. Stringent regulatory guidelines and zero tolerance policy...
Listeria monocytogenes is a major food-borne pathogen and causative agent of a fatal disease, listeriosis. Stringent regulatory guidelines and zero tolerance policy toward this bacterium necessitate rapid, accurate, and reliable methods of identification and subtyping. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) has recently become a method of choice for routine identification of pathogens in clinical settings and has largely replaced biochemical assays. Identification relies on well-curated databases such as SARAMIS. Extensive use of SARAMIS to generate consensus mass spectra, in conjunction with statistical analysis, such as partial least square-discriminant analysis and hierarchical cluster analysis, is useful in subtyping bacteria. While MALDI-ToF MS has been extensively used for pathogen detection, its application in bacterial subtyping has been limited. The protocol describes a MALDI-ToF MS workflow as a single tool for simultaneous identification and subtyping of L. monocytogenes directly from solid culture medium.
Topics: Bacterial Typing Techniques; Humans; Listeria monocytogenes; Listeriosis; Software; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Time Factors; Workflow
PubMed: 32975763
DOI: 10.1007/978-1-0716-0982-8_2 -
BMC Microbiology May 2020Listeria monocytogenes (L. monocytogenes) is a global opportunistic intracellular pathogen that can cause many infections, including meningitis and abortion in humans...
BACKGROUND
Listeria monocytogenes (L. monocytogenes) is a global opportunistic intracellular pathogen that can cause many infections, including meningitis and abortion in humans and animals; thus, L. monocytogenes poses a great threat to public safety and the development of the aquaculture industry. The isolation rate of Listeria monocytogenes in fishery products has always been high. And the pore-forming toxin listeriolysin O (LLO) is one of the most important virulence factors of L. monocytogenes. LLO can promote cytosolic bacterial proliferation and help the pathogen evade attacks from the host immune system. In addition, L. monocytogenes infection can trigger a series of severe inflammatory reactions.
RESULTS
Here, we further confirmed that morin lacking anti-Listeria activity could inhibit LLO oligomerization. We also found that morin can effectively alleviate the inflammation induced by Listeria in vivo and in vitro and exerted an obvious protective effect on infected cells and mice.
CONCLUSIONS
Morin does not possess anti-Listeria activity, neither does it interfere with secretion of LLO. However, morin inhibits oligomerisation of LLO and morin does reduce the inflammation caused during Listeria infection.
Topics: Animals; Bacterial Toxins; Cell Line; Disease Models, Animal; Flavonoids; Gene Expression Regulation, Bacterial; Heat-Shock Proteins; Hemolysin Proteins; Humans; Listeria monocytogenes; Listeriosis; Mice; Protein Multimerization; Virulence
PubMed: 32398085
DOI: 10.1186/s12866-020-01807-6 -
Colloids and Surfaces. B, Biointerfaces Mar 2019A bacteriophage-assisted magnetic separation method was developed for the isolation of Listeria monocytogenes from complex food matrices. The aim of this study is to...
A bacteriophage-assisted magnetic separation method was developed for the isolation of Listeria monocytogenes from complex food matrices. The aim of this study is to understand the effect of phage immobilization methods and the magnetic particle sizes on the phage coupling and infectivity retention of the magnetic particles. In this study, bacteriophage P100-modified magnetic particles (PMMPs) were developed for the separation of L. monocytogenes from food matrices. Three sizes of magnetic particles (MP) (150 nm, 500 nm, and 1 μm) were used for phage immobilization via chemical and physical methods. The coupling ratio of phage was investigated, and the performance of each PMMP complex was evaluated by their L. monocytogenes capture efficiency. When compared to the chemical immobilization method, the physically immobilized PMMP complex achieved a higher capture efficiency initially, with excellent selectivity towards target bacteria. The PMMPs were further tested for selective isolation of L. monocytogenes using real food samples such as ground beef and whole milk.
Topics: Animals; Bacteriophages; Cattle; Colony Count, Microbial; Food Contamination; Food Microbiology; Food Preservation; Listeria monocytogenes; Magnetics; Milk
PubMed: 30562716
DOI: 10.1016/j.colsurfb.2018.12.007 -
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 -
Food Microbiology Oct 2018Pathogen Environmental Monitoring (PEM) programs for Listeria are important to reduce the contamination risk for exposed Ready-To-Eat (RTE) food products with...
Pathogen Environmental Monitoring (PEM) programs for Listeria are important to reduce the contamination risk for exposed Ready-To-Eat (RTE) food products with L. monocytogenes. Specific guidance to identify appropriate sampling sites in individual facilities, including equipment and other sites, will facilitate effective L. monocytogenes control and PEM programs. Key goals of Listeria PEM programs are to (i) identify and eliminate niches that allow for Listeria growth and survival and (ii) verify and validate preventive controls such as sanitation programs and sanitation standard operating procedures (SSOPs), sanitary equipment and facility design. Here, an initial list of 77 sampling sites covering Zones 1-4 was assembled based on current literature and guidance documents with initial classification of sites into (i) Zones 1, 2, 3, and 4; (ii) likely niches or transfer sites, and (iii) verification sites or indicator sites. An expert elicitation that included responses from 16 food safety professionals was used to (i) refine sampling site descriptions and identify 6 new sampling sites that were not included in the original list, (ii) refine classification of sites (e.g., into niches versus transfer sites), and (iii) rank sites on level of importance from 1 to 5. The final sample site list includes sampling sites classified by zone and type of site as well as relative importance of site based on reviewer feedback. This document thus provides an initial set of sites that can be used by industry to help in the development or refinement of Listeria PEM programs. The availability of this ranked list of sampling sites should reduce barriers to development of science based Listeria PEM programs.
Topics: Environmental Microbiology; Expert Testimony; Food Contamination; Food Handling; Food Inspection; Food Microbiology; Humans; Listeria monocytogenes; Workforce
PubMed: 30056959
DOI: 10.1016/j.fm.2017.07.005 -
Food Microbiology Dec 2014Listeria monocytogenes is a major concern for the meat processing industry because many listeriosis outbreaks have been linked to meat product consumption. The aim of...
Listeria monocytogenes is a major concern for the meat processing industry because many listeriosis outbreaks have been linked to meat product consumption. The aim of this study was to elucidate L. monocytogenes diversity and distribution across different Spanish meat processing plants. L. monocytogenes isolates (N = 106) collected from food contact surfaces of meat processing plants and meat products were serotyped and then characterised by multilocus sequence typing (MLST). The isolates were serotyped as 1/2a (36.8%), 1/2c (34%), 1/2b (17.9%) and 4b (11.3%). MLST identified ST9 as the most predominant allelic profile (33% of isolates) followed by ST121 (16%), both of which were detected from several processing plants and meat products sampled in different years, suggesting that those STs are highly adapted to the meat processing environment. Food contact surfaces during processing were established as an important source of L. monocytogenes in meat products because the same STs were obtained in isolates recovered from surfaces and products. L. monocytogenes was recovered after cleaning and disinfection procedures in two processing plants, highlighting the importance of thorough cleaning and disinfection procedures. Epidemic clone (EC) marker ECI was identified in 8.5%, ECIII was identified in 2.8%, and ECV was identified in 7.5% of the 106 isolates. Furthermore, a selection of presumably unrelated ST9 isolates was analysed by multi-virulence-locus sequence typing (MVLST). Most ST9 isolates had the same virulence type (VT11), confirming the clonal origin of ST9 isolates; however, one ST9 isolate was assigned to a new VT (VT95). Consequently, MLST is a reliable tool for identification of contamination routes and niches in processing plants, and MVLST clearly differentiates EC strains, which both contribute to the improvement of L. monocytogenes control programs in the meat industry.
Topics: Animals; Bacterial Typing Techniques; Biodiversity; Food Contamination; Food Handling; Listeria monocytogenes; Meat; Spain
PubMed: 25084653
DOI: 10.1016/j.fm.2014.05.014 -
Methods in Molecular Biology (Clifton,... 2021The behavior of Listeria monocytogenes communities in the food chain is closely associated with their spatial organization. Whether as biofilms on industrial surfaces or...
The behavior of Listeria monocytogenes communities in the food chain is closely associated with their spatial organization. Whether as biofilms on industrial surfaces or as microcolonies in food matrices, the resulting physiological diversification combined with the presence of extracellular polymeric substances (EPS) triggers emergent community functions involved in the pathogen survival and persistence (e.g., tolerance to dehydration, biocides, or preservatives). In this contribution, we present a noninvasive confocal laser microscopy (CLM) protocol allowing exploration of the spatial organization of L. monocytogenes communities on various inert or nutritive materials relevant for the food industry.
Topics: Biofilms; Food Microbiology; Humans; Listeria monocytogenes; Listeriosis; Microscopy, Confocal
PubMed: 32975771
DOI: 10.1007/978-1-0716-0982-8_10