-
Brazilian Journal of Microbiology :... Jul 2019This study focuses on the prevalence of Listeria monocytogenes (Lm) in pork meat and on inert surfaces from slaughterhouses in Sonora, Mexico. A total of 21 Lm were...
This study focuses on the prevalence of Listeria monocytogenes (Lm) in pork meat and on inert surfaces from slaughterhouses in Sonora, Mexico. A total of 21 Lm were obtained from 103 samples, giving a prevalence of 20.3%. The prevalence of Lm in pork loin was 15.9% and 20.8% for inert surfaces in Federal Inspection Type (FIT) slaughterhouses. For non-FIT slaughterhouses, the prevalence was 25.7%. PCR amplification of genomic DNA from the Lm isolates revealed the presence of the hlyA gene, suggesting a pathogenic nature for these isolates. The isolates obtained in this work all clustered with Lm, according to our phylogenetic analysis based on the 16S rDNA sequence. This Lm cluster indicates that Lm isolates 7-2, 4, 2-1, 10B, 8, 3, 3-3, and 9 share 16S rRNA identity with other Lm isolates that have been reported as foodborne pathogens (rR2-502, J1817, J1816, J1926) and that are involved in foodborne outbreaks. The most commonly detected serotypes were 1/2a and 1/2b. All isolates displayed differential responses to the assayed antibiotics, and most isolates were able to grow in the presence of penicillin G, or both penicillin and penicillin-derived (oxacillin) antibiotics.
Topics: Abattoirs; Animals; Anti-Bacterial Agents; Food Contamination; Food Handling; Listeria monocytogenes; Mexico; Microbial Sensitivity Tests; Phylogeny; Red Meat; Swine
PubMed: 30976991
DOI: 10.1007/s42770-019-00073-7 -
The Journal of Infectious Diseases May 2015
Topics: Animals; Bacterial Toxins; Female; Flavonoids; Flavonols; Gene Expression Regulation, Bacterial; Heat-Shock Proteins; Hemolysin Proteins; Listeria monocytogenes
PubMed: 25231016
DOI: 10.1093/infdis/jiu521 -
Scientific Reports Oct 2021In this study we investigated how cell origin could affect the efficacy of an antimicrobial treatment (mild heating combined with terpenoids) in Listeria monocytogenes...
In this study we investigated how cell origin could affect the efficacy of an antimicrobial treatment (mild heating combined with terpenoids) in Listeria monocytogenes Scott A, considering cells from: 1. single colony, 2. glycerol stock, 3. cold adapted culture, and 4. fresh culture in stationary phase. After treatment, culturability on BHI medium and viability assessed by flow cytometry were evaluated. Our results showed that the cell origin significantly impacted viability and culturability of L. monocytogenes towards antimicrobial treatment. The mild heat treatment combined or not with terpenoids mainly affected culturability rather than viability, although the culturability of cells from single colony was less impacted. Therefore, to mimic the worst scenario, these latter were selected to contaminate Gorgonzola rind and roast beef slices and we evaluated the ability of L. monocytogenes cells to recover their culturability (on ALOA agar medium) and to growth on the food matrix stored at 4 °C for 7 days. Our results suggest that only Gorgonzola rind allowed a partial recovery of the culturability of cells previously heated in presence or not of terpens. In conclusion, we found a connection between the cell history and sensitivity toward an antimicrobial treatment, underlying the importance to standardize the experimental procedures (starting from the cells to be used in the assay) in the assessment of cell sensitivity to a specific treatment. Finally, our study clearly indicated that VBNC cells can resuscitate under favorable conditions on a food matrix, becoming a threat for consumer's health.
Topics: Anti-Bacterial Agents; Bacterial Physiological Phenomena; Colony Count, Microbial; Culture Media; Disinfection; Food Microbiology; Listeria monocytogenes; Listeriosis; Microbial Sensitivity Tests; Microbial Viability; Temperature
PubMed: 34711898
DOI: 10.1038/s41598-021-00767-9 -
Growth, viability and architecture of biofilms of Listeria monocytogenes formed on abiotic surfaces.Brazilian Journal of Microbiology :... 2017The pathogenic bacterium Listeria monocytogenes can persist in food processing plants for many years, even when appropriate hygienic measures are in place, with...
The pathogenic bacterium Listeria monocytogenes can persist in food processing plants for many years, even when appropriate hygienic measures are in place, with potential for contaminating ready-to-eat products and, its ability to form biofilms on abiotic surfaces certainly contributes for the environmental persistence. In this research, L. monocytogenes was grown in biofilms up 8 days attached to stainless steel and glass surfaces, contributing for advancing the knowledge on architecture of mature biofilms, since many literature studies carried out on this topic considered only early stages of cell adhesion. In this study, biofilm populations of two strains of L. monocytogenes (serotypes 1/2a and 4b) on stainless steel coupons and glass were examined using regular fluorescence microscopy, confocal laser scanning microscopy and classic culture method. The biofilms formed were not very dense and microscopic observations revealed uneven biofilm structures, with presence of exopolymeric matrix surrounding single cells, small aggregates and microcolonies, in a honeycomb-like arrangement. Moreover, planktonic population of L. monocytogenes (present in broth media covering the abiotic surface) remained stable throughout the incubation time, which indicates an efficient dispersal mechanism, since the culture medium was replaced daily. In conclusion, even if these strains of L. monocytogenes were not able to form thick multilayer biofilms, it was noticeable their high persistence on abiotic surfaces, reinforcing the need to focus on measures to avoid biofilm formation, instead of trying to eradicate mature biofilms.
Topics: Bacterial Adhesion; Biofilms; Food Handling; Glass; Listeria monocytogenes; Stainless Steel
PubMed: 28237677
DOI: 10.1016/j.bjm.2017.01.004 -
FEMS Microbiology Letters Feb 2020A wide variety of foods can be contaminated with Listeria species, especially L. monocytogenes. Ready-to-eat (RTE) foods are predominantly associated with human...
A wide variety of foods can be contaminated with Listeria species, especially L. monocytogenes. Ready-to-eat (RTE) foods are predominantly associated with human listeriosis caused by L. monocytogenes. Therefore, this study aimed to assess the presence of Listeria species in RTE foods and to characterize L. monocytogenes isolates by means of detection of virulence markers, serotypes and genetic relatedness. Of the 300 RTE food samples, 59 (19.7%) were positive for Listeria species: L. innocua (13.3%), L. monocytogenes (5%), L. welshimerii (2.3%), L. grayi subsp. murrayi (1.3%), L. grayi (1%), L. ivanovii (1%) and L. ivanovi subsp. londoniensis (0.3%). All L. monocytogenes isolates identified were positive for the actA, iap, inlA, inlB, inlC, inlJ, plcA and prfA virulence genes and biofilm. The isolates were serotyped as 1/2c (33.3%), 4b (26.7%), 1/2a (26.7%), 1/2b (6.7%) and 3c (6.7%) by the multiplex-PCR and agglutination methods. PCR-restriction fragment length polymorphism with AluI and MluCI resulted in three and two profiles, respectively. Pulsed-field gel electrophoresis differentiated the L. monocytogenes isolates into 15 ApaI and 12 AscI patterns. Antimicrobial resistance of all Listeria isolates was determined by the disk diffusion method. Most L. monocytogenes isolates were sensitive to antimicrobials used in the treatment of listeriosis. This study shows the presence of potential pathogenic and antimicrobial-resistant L. monocytogenes in RTE foods that may lead to consumer health risks.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Food Microbiology; Genes, Bacterial; Listeria; Listeria monocytogenes; Microbial Sensitivity Tests; Prevalence; Serogroup; Virulence
PubMed: 31926017
DOI: 10.1093/femsle/fnaa006 -
Journal of Bacteriology Apr 2020The capacity of to adapt to environmental changes is facilitated by a large number of regulatory proteins encoded by its genome. Among these proteins are the...
The capacity of to adapt to environmental changes is facilitated by a large number of regulatory proteins encoded by its genome. Among these proteins are the uncharacterized LysR-type transcriptional regulators (LTTRs). LTTRs can work as positive and/or negative transcription regulators at both local and global genetic levels. Previously, our group determined by comparative genome analysis that one member of the LTTRs (NCBI accession no. WP_003734782) was present in pathogenic strains but absent from nonpathogenic strains. The goal of the present study was to assess the importance of this transcription factor in the virulence of strain F2365 and to identify its regulons. An strain lacking (the F2365Δ strain) displayed significant reductions in cell invasion of and adhesion to Caco-2 cells. In plaque assays, the deletion of resulted in a 42.86% decrease in plaque number and a 13.48% decrease in average plaque size. Furthermore, the deletion of also attenuated the virulence of in mice following oral and intraperitoneal inoculation. The analysis of transcriptomics revealed that the transcript levels of 139 genes were upregulated, while 113 genes were downregulated in the F2365Δ strain compared to levels in the wild-type bacteria. -repressed genes included ABC transporters, important for starch and sucrose metabolism as well as glycerolipid metabolism, flagellar assembly, quorum sensing, and glycolysis/gluconeogenesis. Conversely, activated the expression of genes related to fructose and mannose metabolism, cationic antimicrobial peptide (CAMP) resistance, and beta-lactam resistance. These data suggested that contributed to virulence by broad impact on multiple pathways of gene expression. is the causative agent of listeriosis, an infectious and fatal disease of animals and humans. In this study, we have shown that contributes to pathogenesis and replication in cell lines. We also highlight the importance of in regulating the transcription of genes involved in different pathways that might be essential for the growth and persistence of in the host or under nutrient limitation. Better understanding pathogenesis and the role of various virulence factors is necessary for further development of prevention and control strategies.
Topics: Animals; Bacterial Proteins; Caco-2 Cells; Female; Gene Expression Regulation, Bacterial; Humans; Listeria monocytogenes; Listeriosis; Mice; Mice, Inbred BALB C; Regulon; Transcription Factors; Virulence
PubMed: 32179628
DOI: 10.1128/JB.00087-20 -
Applied and Environmental Microbiology May 2022The Gram-positive bacterium Listeria monocytogenes is an important pathogen that causes a foodborne illness with a high percentage of fatalities. Surface proteins,...
The Gram-positive bacterium Listeria monocytogenes is an important pathogen that causes a foodborne illness with a high percentage of fatalities. Surface proteins, specifically expressed from a wide range of L. monocytogenes serotypes under selective enrichment culture conditions, can serve as targets for the detection and isolation of this pathogen using antibody-based methods. Among a number of surface proteins identified by mass spectrometry in a previous proteomic study, six candidates (annotated as LMOf2365_0148, LMOf2365_0312, LMOf2365_0546, LMOf2365_1883, LMOf2365_2111, and LMOf2365_2742) were selected here for investigating their expression in the bacterial cells cultured by raising rabbit polyclonal antibodies (PAbs) against the recombinant form of each candidate. These protein candidates contained regions conserved among various L. monocytogenes isolates but variable in other species. LMOf2365_0148, an uncharacterized protein with a LPXTG motif accountable for covalent linkage to the cell wall peptidoglycan, exhibited a strong reaction signal from anti-LMOf2365_0148 PAb binding to the cell surface, as detected by immunofluorescence microscopy. Further study, through the generation of a panel of mouse monoclonal antibodies (MAbs) to the recombinant LMOf2365_0148, showed that one of the MAbs, M3686, reacted to bacterial isolates belonging to all three lineages of L. monocytogenes under Health Canada's standard enrichment culture conditions (MFHPB-07 and MFHPB-30). These results demonstrated the potential of using LMOf2365_0148 as a surface biomarker, in conjunction with specific MAbs developed here, for the isolation and detection of L. monocytogenes from foods and food processing environments. Strains of Listeria monocytogenes are differentiated serologically into at least 13 serotypes and grouped phylogenetically into 4 distinct lineages (I, II, III, and IV). No single monoclonal antibody (MAb) reported to date is capable of binding to the surface of L. monocytogenes strains representing all the serotypes. This study assessed the expression of six surface proteins selected from a previous proteomic study and demonstrated that surface protein LMOf2365_0148 has the greatest potential as a surface biomarker. A panel of 24 MAbs to LMOf2365_0148 were assessed extensively, revealing that one of the MAbs, M3686, reacted to a wide range of L. monocytogenes isolates (lineage I, II, and III isolates) grown under standard enrichment culture conditions and thus led to the conclusion that LMOf2365_0148 is a useful novel surface biomarker for identifying, detecting, and isolating the pathogen from food and environmental samples.
Topics: Antibodies, Monoclonal; Biomarkers; Listeria; Listeria monocytogenes; Membrane Proteins; Proteomics
PubMed: 35477262
DOI: 10.1128/aem.00035-22 -
Food Microbiology Sep 2014A total of 336 Listeria isolates from ready-to-eat (RTE) meat products and meat-processing environments, consisting of 206 Listeria monocytogenes, and 130 Listeria...
A total of 336 Listeria isolates from ready-to-eat (RTE) meat products and meat-processing environments, consisting of 206 Listeria monocytogenes, and 130 Listeria innocua isolates, were characterized by disc diffusion assay and minimum inhibitory concentration (MIC) values for antimicrobial susceptibility against twenty antimicrobials. Resistance to one or two antimicrobials was observed in 71 L. monocytogenes isolates (34.5%), and 56 L. innocua isolates (43.1%). Multidrug resistance was identified in 24 Listeria isolates, 18 belonging to L. innocua (13.9%) and 6 to L. monocytogenes (2.9%). Oxacillin resistance was the most common resistance phenotype and was identified in 100% Listeria isolates. A medium prevalence of resistance to clindamycin (39.3% isolates) and low incidence of resistance to tetracycline (3.9% isolates) were also detected. Listeria isolates from RTE meat products displayed higher overall antimicrobial resistance (31.3%) than those from the environment (13.4%). All the strains assayed were sensitive to the preferred antibiotics used to treat listeriosis. Results showed that although antimicrobial resistance in L. monocytogenes still occurs at a low prevalence, L. innocua can form a reservoir of resistance genes which may transfer between bacterial species, including transference to organisms capable of causing disease in humans.
Topics: Abattoirs; Anti-Bacterial Agents; Drug Resistance, Bacterial; Food Contamination; Food Handling; Listeria; Listeria monocytogenes; Meat Products; Microbial Sensitivity Tests
PubMed: 24929718
DOI: 10.1016/j.fm.2014.02.017 -
Analytica Chimica Acta Aug 2019Foodborne pathogens pose one of the greatest challenges facing public health in the modern day. One important pathogen, Listeria monocytogenes, is known to be...
Foodborne pathogens pose one of the greatest challenges facing public health in the modern day. One important pathogen, Listeria monocytogenes, is known to be challenging to detect and identify. Three serovars cause most of the Listeria related food-borne illnesses, which the Centers for Disease Control currently utilizes a combination of pulsed-field gel electrophoresis and whole genome sequencing for identification and the determination of clusters and outbreaks. There is a potential method for rapid collection of epidemiological information by exploiting the electrokinetic and dielectrophoretic properties of the L. monocytogenes serovars. Using dielectrophoresis, the three most commonly identified serovars of L. monocytogenes can be distinguished from each other. The electrokinetic and dielectrophoretic mobilities of each serovar was determined through a combination of electrokinetic velocity and dielectrophoretic trapping assessments, in conjunction with finite element multi-physics modeling. A mathematical model of the data, which defines the various factors of dielectrophoretic trapping, is utilized and verified based on the behavior of L. monocytogenes in the microchannel. The trapping condition for the serovars were evaluated as 2.8±0.2×10, 2.2±0.2×10, and 2.2±0.3×10Vm and the electrokinetic mobility was assessed to be 19±0.7, 17±0.7, and for the L. monocytogenes serovars 1/2a, 1/2b, and 4b, respectively.
Topics: Electrophoresis; Listeria monocytogenes; Microfluidic Analytical Techniques
PubMed: 31072476
DOI: 10.1016/j.aca.2019.03.019 -
MBio Apr 2018Biodiversity analysis of the foodborne pathogen recently revealed four serotype 4b major hypervirulent clonal complexes (CCs), i.e., CC1, CC2, CC4, and CC6....
Biodiversity analysis of the foodborne pathogen recently revealed four serotype 4b major hypervirulent clonal complexes (CCs), i.e., CC1, CC2, CC4, and CC6. Hypervirulence was indicated by overrepresentation of these clones, and serotype 4b as a whole, among human clinical isolates in comparison to food. However, data on potential source-dependent partitioning among serotype 4b clones in diverse regions are sparse. We analyzed a panel of 347 serotype 4b isolates, primarily from North America, to determine the distribution of clones in humans, other animals, food, and water. CC1, CC2, CC4, and CC6 predominated, but surprisingly, only three clones, i.e., CC2 and the singleton sequence types (STs) ST382 and ST639, exhibited significant source-dependent associations, with higher propensity for food (CC2) or water (ST382 and ST639) than other sources. Pairwise comparisons between human and food isolates identified CC4 as the only serotype 4b clone significantly overrepresented among human isolates. Our analysis also revealed several serotype 4b clones emerging in North America. Two such emerging clones, ST382 (implicated in several outbreaks since 2014) and ST639, were primarily encountered among human and water isolates. Findings suggest that in spite of the ubiquity of CC1, CC2, CC4, and CC6, regional heterogeneity in serotype 4b is substantially larger than previously surmised. Analysis of even large strain panels from one region may not adequately predict clones unique to, and emerging in, other areas. Serotype 4b clonal complexes may differ in ecological niche preference, suggesting the need to further elucidate reservoirs and vehicles, especially for emerging clones. In , serotype 4b strains are leading contributors to human disease, but intraserotype distributions among different sources and regions remain poorly elucidated. Analysis of 347 serotype 4b isolates from four different sources, mostly from North America, confirmed the overall predominance of the major clones CC1, CC2, CC4, and CC6 but found that only CC4 was significantly associated with human disease, while CC2 was significantly associated with food. Remarkably, several emerging clones were identified among human isolates from North America, with some of these also exhibiting a propensity for surface water. The latter included the singleton clones ST382, implicated in several outbreaks in the United States since 2014, and ST639. These clones were noticeably underrepresented among much larger panels from other regions. Though associated with North America for the time being, they may eventually become globally disseminated through the food trade or other venues.
Topics: Animals; Biodiversity; Ecosystem; Food Microbiology; Genotype; Humans; Listeria monocytogenes; Listeriosis; Molecular Epidemiology; Molecular Typing; North America; Serogroup; Water Microbiology
PubMed: 29666282
DOI: 10.1128/mBio.00396-18