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Infection and Immunity Apr 2019is considered a nonpathogenic species. Natural atypical hemolytic isolates have been reported but have not been characterized in detail. Here, we report the genomic... (Comparative Study)
Comparative Study
is considered a nonpathogenic species. Natural atypical hemolytic isolates have been reported but have not been characterized in detail. Here, we report the genomic and functional characterization of representative isolates from the two known natural hemolytic clades. Whole-genome sequencing confirmed the presence of pathogenicity islands (LIPI) characteristic of species. Functional assays showed that LIPI-1 and genes are transcribed, and the corresponding gene products are expressed and functional. Using and assays, we show that atypical hemolytic is virulent, can actively cross the intestinal epithelium, and spreads systemically to the liver and spleen, albeit to a lesser degree than the reference EGDe strain. Although human exposure to hemolytic is likely rare, these findings are important for food safety and public health. The presence of virulence traits in some clades supports the existence of a common virulent ancestor of and .
Topics: Animals; Bacterial Proteins; Bird Diseases; Ducks; Feces; Galliformes; Genome, Bacterial; Genomic Islands; Humans; Listeria; Listeria monocytogenes; Listeriosis; Phylogeny; Serotyping; Virulence; Whole Genome Sequencing
PubMed: 30670551
DOI: 10.1128/IAI.00758-18 -
Food Microbiology Jun 2019The presence of Listeria monocytogenes was evaluated in a small-scale meat processing facility in Montenegro during 2011-2014. L. monocytogenes isolates from traditional...
The presence of Listeria monocytogenes was evaluated in a small-scale meat processing facility in Montenegro during 2011-2014. L. monocytogenes isolates from traditional meat products and environmental swabs were subjected to a) molecular characterization b) serotyping by both multiplex PCR and next generation sequencing (NGS) c) potential antimicrobial resistance (AMR) was assessed by extraction of specific genes from NGS data and d) screening for the presence of some disinfectant resistance markers. Overall, traditional meat products were contaminated, most likely from incoming raw materials, with 4 major specific STs of L. monocytogenes (ST515, ST8, ST21, ST121) representing 4 clonal complexes (CC1, CC8, CC21, CC121) identified during the four-year period. These strains belonged to serogroup IIa which predominated, followed by IVb (ST515, CC1). The strains from environmental swabs belonged, exclusively, to ST21 and were isolated from cutting board and floor swabs in 2011. Furthermore, we found Tn6188, a novel transposon conferring tolerance to BC, to be specific to sequence type ST121. In addition, antimicrobial resistance genes mprF and fosX were present in clonal complexes CC21 and CC121, while complexes CC8 and CC1 exclusively harbored the mprF antimicrobial resistance gene.
Topics: Bacterial Proteins; Biofilms; DNA Transposable Elements; Drug Resistance, Bacterial; Environmental Microbiology; Food Handling; Food Microbiology; Genome, Bacterial; Listeria monocytogenes; Meat Products; Montenegro; Red Meat; Serogroup; Serotyping
PubMed: 30621866
DOI: 10.1016/j.fm.2018.12.005 -
Journal of Bacteriology Jan 2022The survival of microbial cells under changing environmental conditions requires an efficient reprogramming of transcription, often mediated by alternative sigma...
The survival of microbial cells under changing environmental conditions requires an efficient reprogramming of transcription, often mediated by alternative sigma factors. The Gram-positive human pathogen Listeria monocytogenes senses and responds to environmental stress mainly through the alternative sigma factor σ (SigB), which controls expression of the general stress response regulon. SigB activation is achieved through a complex series of phosphorylation/dephosphorylation events culminating in the release of SigB from its anti-sigma factor RsbW. At the top of the signal transduction pathway lies a large multiprotein complex known as the stressosome that is believed to act as a sensory hub for stresses. Following signal detection, stressosome proteins become phosphorylated. Resetting of the stressosome is hypothesized to be exerted by a putative phosphatase, RsbX, which presumably removes phosphate groups from stressosome proteins poststress. We addressed the role of the RsbX protein in modulating the activity of the stressosome and consequently regulating SigB activity in L. monocytogenes. We show that RsbX is required to reduce SigB activation levels under nonstress conditions and that it is required for appropriate SigB-mediated stress adaptation. A strain lacking RsbX displayed impaired motility and biofilm formation and also an increased survival at low pH. Our results could suggest that absence of RsbX alters the multiprotein composition of the stressosome without dramatically affecting its phosphorylation status. Overall, the data show that RsbX plays a critical role in modulating the signal transduction pathway by blocking SigB activation under nonstressed conditions. Pathogenic bacteria need to sense and respond to stresses to survive harsh environments and also to turn off the response when no longer facing stress. Activity of the stress sigma factor SigB in the human pathogen Listeria monocytogenes is controlled by a hierarchic system having a large stress-sensing multiprotein complex known as the stressosome at the top. Following stress exposure, proteins in the stressosome become phosphorylated, leading to SigB activation. We have studied the role of a putative phosphatase, RsbX, which is hypothesized to dephosphorylate stressosome proteins. RsbX is critical not only to switch off the stress response poststress but also to keep the activity of SigB low at nonstressed conditions to prevent unnecessary gene expression and save energy.
Topics: Biofilms; Gene Expression Regulation, Bacterial; Listeria monocytogenes; Mutation; Sigma Factor; Stress, Physiological
PubMed: 34694900
DOI: 10.1128/JB.00486-21 -
PloS One 2021Non-coding RNAs (ncRNAs) have gained increasing attention as their diverse roles in virulence and environmental stress in Listeria monocytogenes have become clearer. The...
Non-coding RNAs (ncRNAs) have gained increasing attention as their diverse roles in virulence and environmental stress in Listeria monocytogenes have become clearer. The ncRNA rliB is an atypical member of the CRISPR family, conserved at the same genomic locus in all analyzed L. monocytogenes genomes and also in other Listeria species. In this study, rliB defective mutants (Lm3-22-ΔrliB) were constructed by homologous recombination. The growth cycle of Lm3-22-ΔrliB mutants was slower than that of wild-type Lm3-22. The sensitivity of Lm3-22-ΔrliB to the Listeria phage vB-LmoM-SH3-3 was significantly increased, and the efficiency of plaque formation was enhanced by 128 fold. Compared with wild type, the adhesion and invasion of Lm3-22-ΔrliB decreased significantly (9.3% and 1.33%, respectively). After 4 hours of infection, the proliferation of Lm3-22-ΔrliB in RAW264.7 cells also decreased significantly. Transcription level of invasion-related surface proteins showed that the internalin genes lmo0610 and lm0514, and the peptidoglycan binding protein gene lmo1799 in Lm3-22-ΔrliB were significantly increased. In addition, after interaction with phage, the transcription levels of inlA, lmo0610, lmo1799, lmo2085, and lmo0514 in Lm3-22-ΔrliB cells were significantly upregulated, while inlB was downregulated, compared with Lm3-22 control group with phage treatment. Therefore, rliB deletion effectively regulated the interaction between Listeria and phage, weaken its invasion ability, and provided a new theoretical basis for biocontrol of phage.
Topics: Animals; Bacterial Adhesion; Bacterial Proteins; Bacteriophages; Gene Expression Regulation, Bacterial; Homologous Recombination; Listeria monocytogenes; Mice; Microbial Viability; Mutation; RAW 264.7 Cells; RNA, Bacterial; RNA, Untranslated
PubMed: 34928977
DOI: 10.1371/journal.pone.0260768 -
Tropical Animal Health and Production Jan 2021The frequency of Listeria monocytogenes isolates collected from a total of 1150 samples including food (n = 300), livestock (n = 50), and human clinical...
The frequency of Listeria monocytogenes isolates collected from a total of 1150 samples including food (n = 300), livestock (n = 50), and human clinical (n = 800) was evaluated during 2008-2016. Antimicrobial resistance patterns, virulence factors, and molecular characteristics of these isolates were analyzed using disk diffusion method, sequencing, serotyping, and pulsed-field gel electrophoresis (PFGE). The analysis of 44 L. monocytogenes isolates showed that 72.7% (32 of 44) of all the isolates belonged to Serotype 1/2c, and 15.9% (7 of 44) belonged to Serotype 3c. All 44 isolates were resistant to one or more antimicrobial agents with the most frequent resistance to penicillin (75%) and tetracycline (47.7%). Of the 44 L. monocytogenes strains, 100, 69.2, and 62.5% of livestock, human, and food strains were resistant to penicillin, respectively. Using pulsed-field gel electrophoresis (PFGE) technique, the isolates' genetic diversity was determined, and 28 PFGE patterns with 8 common (CT) and 20 single types (ST) were identified. This study highlights the high prevalence of Serotype 1/2c in clinical and livestock samples, while different serotypes were observed in food samples. The presence of rare serotypes such as 4c, belonging to the Lineage III, as well as 4e and 1/2c which are infrequent in Iran indicates that paying attention to uncommon serotypes, especially 1/2c, during the listeriosis outbreaks is necessary.
Topics: Animals; Bacterial Typing Techniques; Drug Resistance, Bacterial; Electrophoresis, Gel, Pulsed-Field; Food Microbiology; Humans; Iran; Listeria monocytogenes; Listeriosis; Livestock; Molecular Typing; Serotyping; Virulence
PubMed: 33454847
DOI: 10.1007/s11250-021-02569-7 -
Risk Analysis : An Official Publication... Jan 2015Evaluations of Listeria monocytogenes dose-response relationships are crucially important for risk assessment and risk management, but are complicated by considerable...
Evaluations of Listeria monocytogenes dose-response relationships are crucially important for risk assessment and risk management, but are complicated by considerable variability across population subgroups and L. monocytogenes strains. Despite difficulties associated with the collection of adequate data from outbreak investigations or sporadic cases, the limitations of currently available animal models, and the inability to conduct human volunteer studies, some of the available data now allow refinements of the well-established exponential L. monocytogenes dose response to more adequately represent extremely susceptible population subgroups and highly virulent L. monocytogenes strains. Here, a model incorporating adjustments for variability in L. monocytogenes strain virulence and host susceptibility was derived for 11 population subgroups with similar underlying comorbidities using data from multiple sources, including human surveillance and food survey data. In light of the unique inherent properties of L. monocytogenes dose response, a lognormal-Poisson dose-response model was chosen, and proved able to reconcile dose-response relationships developed based on surveillance data with outbreak data. This model was compared to a classical beta-Poisson dose-response model, which was insufficiently flexible for modeling the specific case of L. monocytogenes dose-response relationships, especially in outbreak situations. Overall, the modeling results suggest that most listeriosis cases are linked to the ingestion of food contaminated with medium to high concentrations of L. monocytogenes. While additional data are needed to refine the derived model and to better characterize and quantify the variability in L. monocytogenes strain virulence and individual host susceptibility, the framework derived here represents a promising approach to more adequately characterize the risk of listeriosis in highly susceptible population subgroups.
Topics: Host-Parasite Interactions; Listeria monocytogenes; Models, Theoretical; Virulence
PubMed: 24975545
DOI: 10.1111/risa.12235 -
Applied and Environmental Microbiology Jun 2024The foodborne pathogen is differentiated into four distinct lineages which differ in their virulence. It remains unknown, however, whether the four lineages also differ...
The foodborne pathogen is differentiated into four distinct lineages which differ in their virulence. It remains unknown, however, whether the four lineages also differ with respect to their ability to persist in food processing facilities, their resistance to high pressure, a preservation method that is used commercially for control on ready-to-eat meats, and their ability to form biofilms. This study aimed to determine differences in the pressure resistance and biofilm formation of 59 isolates of representing lineages I and II. Furthermore, the genetic similarity of 9 isolates of that were obtained from a meat processing facility over a period of 1 year and of 20 isolates of from food processing facilities was analyzed to assess whether the ability of the lineages of to persist in these facilities differs. Analysis of 386 genomes with respect to the source of isolation revealed that genomes of lineage II are over-represented in meat isolates when compared with clinical isolates. Of the 38 strains of that persisted in food processing facilities (this study or published studies), 31 were assigned to lineage II. Isolates of lineage I were more resistant to treatments at 400 to 600 MPa. The thickness of biofilms did not differ between lineages. In conclusion, strains of lineage II are more likely to persist in food processing facilities while strains of lineage I are more resistant to high pressure.IMPORTANCE substantially contributes to the mortality of foodborne disease in developed countries. The virulence of strains of four lineages of differs, indicating that risks associated with the presence of are lineage specific. Our study extends the current knowledge by documentation that the lineage-level phylogeny of plays a role in the source of isolation, in the persistence in food processing facilities, and in the resistance to pathogen intervention technologies. In short, the control of risks associated with the presence of in food is also lineage specific. Understanding the route of contamination is an important factor to consider when designing improved control measures.
Topics: Listeria monocytogenes; Phylogeny; Food Microbiology; Food Handling; Biofilms; Food-Processing Industry; Meat Products
PubMed: 38809044
DOI: 10.1128/aem.00861-24 -
Prevalence and populations of Listeria monocytogenes in meat products retailed in Sao Paulo, Brazil.Foodborne Pathogens and Disease Dec 2014This study evaluated the prevalence of the populations and serotypes of Listeria monocytogenes in 552 refrigerated samples of ground beef, chicken leg, hot dog, and pork...
This study evaluated the prevalence of the populations and serotypes of Listeria monocytogenes in 552 refrigerated samples of ground beef, chicken leg, hot dog, and pork sausage collected in supermarkets in the city of Sao Paulo, SP, Brazil, between May 2008 and July 2009. The supermarkets were selected after stratification by geographical region and by random draw. Tests for presence and enumeration of L. monocytogenes were based on ISO 11290-1:1996/Amd.1:2004 and ISO 11290-2:1998 methods, respectively. Listeria spp. were detected in 469 (85.0%) of the studied meat products. The most frequently isolated species was L. innocua (64.1%), followed by L. monocytogenes (48.7%), L. welshimeri (13.4%), L. seeligeri (7.1%), L. ivanovii (0.2%), and L. grayi subspecies murrayi (0.2%). L. monocytogenes was detected in 269 (48.7%) samples, with highest prevalence in ground beef (59.4%) followed by chicken legs (58.0%), pork sausages (39.8%), and hot dogs (37.7%). The populations were <10(2) colony-forming units/g in the majority of samples (62.5%). Prevalence of serotypes varied according to the type of meat product. These data are relevant for estimating the risks of listeriosis associated with consumption of meat products in Sao Paulo, and for establishing science-based intervention strategies aimed at reducing these risks, especially for pregnant women and immunocompromised individuals.
Topics: Animals; Brazil; Cattle; Chickens; Food Contamination; Listeria monocytogenes; Meat Products; Swine
PubMed: 25407460
DOI: 10.1089/fpd.2014.1809 -
Letters in Applied Microbiology Apr 2017Listeria monocytogenes is a pathogenic bacterium, with human disease and infection linked to dairy products, seafood, ready-to-eat meat and raw & undercooked meats....
UNLABELLED
Listeria monocytogenes is a pathogenic bacterium, with human disease and infection linked to dairy products, seafood, ready-to-eat meat and raw & undercooked meats. Stainless steel is the most common food preparation surface and therefore, it is important to understand how food storage conditions such as surface materials, temperature and relative humidity can affect survival of L. monocytogenes. In this study, survival of L. monocytogenes on stainless steel was investigated at three temperatures (4, 10 and 21°C), each approx. 11, 50 and 85% humidity. Results indicate that the lower the temperature, the more cells were recovered in all three humidity environments, while medium humidity enhances survival, irrespective of temperature. Lower humidity decreases recovery at all temperatures. These data support the guidance noted above that humidity control is important, and that lower humidity environments are less likely to support retention of viable L. monocytogenes on a stainless steel surface.
SIGNIFICANCE AND IMPACT OF THE STUDY
Understanding survival of potential food-borne pathogens is essential for the safe production and preparation of food. While it has long been 'common knowledge' that relative humidity can affect the growth and survival of micro-organisms, this study systematically describes the survival of L. monocytogenes on stainless steel under varying humidity and temperatures for the first time. The outcomes from this paper will allow those involved with food manufacture and preparation to make informed judgement on environmental conditions relating to humidity control, which is lacking in the food standards guidelines.
Topics: Colony Count, Microbial; Food Microbiology; Humans; Humidity; Listeria monocytogenes; Listeriosis; Microbial Viability; Stainless Steel; Temperature
PubMed: 28101930
DOI: 10.1111/lam.12714 -
Food Microbiology Sep 2017Listeria monocytogenes is a foodborne pathogen commonly found in environments of seafood processing, thus presenting a challenge for eradication from seafood processing...
Listeria monocytogenes is a foodborne pathogen commonly found in environments of seafood processing, thus presenting a challenge for eradication from seafood processing facilities. Monitoring the prevalence and subtype diversity of L. monocytogenes together with phages that are specific to Listeria spp. ("Listeria phages") will provide knowledge on the bacteria-phage ecology in food processing plants. In this work, a total of 595 samples were collected from raw material, finished seafood products and environmental samples from different sites of a seafood processing plant during 17 sampling visits in 1.5 years of study. L. monocytogenes and Listeria spp. (non-monocytogenes) were found in 22 (3.7%) and 43 (7.2%) samples, respectively, whereas 29 Listeria phages were isolated from 9 (1.5%) phage-positive samples. DNA fingerprint analysis of L. monocytogenes isolates revealed 11 Random Amplified Polymorphic DNA (RAPD) profiles, with two subtypes were frequently observed over time. Our data reveal a presence of Listeria phages within the same seafood processing environments where a diverse set of L. monocytogenes subtypes was also found. Although serotype 4b was observed at lower frequency, data indicate that isolates from this seafood processing plant belonged to both epidemiologically important serotypes 1/2a and 4b, which may suggest a potential public health risk. Phages (all showed a unique genome size of 65 ± 2 kb) were classified into 9 host range groups, representing both broad- and narrow-host range. While most L. monocytogenes isolates from this facility were susceptible to phages, five isolates showed resistance to 12-20 phages. Variations in phage host range among Listeria phages isolated from food processing plant may affect a presence of a diverse set of L. monocytogenes isolates derived from the same processing environment in Thailand.
Topics: Animals; Bacteriophages; Food Contamination; Food Handling; Host Specificity; Listeria monocytogenes; Longitudinal Studies; Seafood; Thailand
PubMed: 28576358
DOI: 10.1016/j.fm.2017.03.014