Listeria Monocytogenes Serotype Research Articles

Complete genome sequence of a Listeria monocytogenes serotype 1 isolated from a critically ill patient in Italy, 2023.

Listeria monocytogenes, a concerning foodborne pathogen, causes severe infections in vulnerable subjects such as pregnant women and the elderly. In this article, we present the complete genome sequence of P4_LIS, an L. monocytogenes isolated from a patient with invasive bacteria infection.

Effect of low doses of biocides on the susceptibility of Listeria monocytogenes and Salmonella enterica to various antibiotics of clinical importance

The use of subinhibitory concentrations of biocides in food processing environments requires special attention because it is related to potential increases in antibiotic resistance. In this study, we determined the effect of exposure to low doses of four biocides (sodium hypochlorite, SHY; benzalkonium chloride, BZK; peracetic acid, PAA; trisodium phosphate, TSP) on the resistance to 10 antibiotics and on the hydrophobicity of the cellular surface of a strain of Listeria monocytogenes serotype 1/2 b (LM) and a strain of Salmonella enterica serotype Agona (SA), both of meat origin. The cultures were exposed at 37 °C in tryptone soya broth to increasing concentrations of the biocides, starting with half the minimum inhibitory concentration (MIC/2) and incrementing by 1.5 times the concentration until growth was no longer observed, calculating the MIC of the antibiotics before (control cultures) and after exposure. After exposure to TSP, LM was able to grow in the presence of a concentration of the biocide 2.53 times higher than the MIC of unexposed cultures. No adaptation was observed for SHY, BZK or PAA. SE demonstrated adaptation to BZK (it tolerated a concentration 1.13 times higher than the MIC for the unadapted strain) and PAA (2.53 times). LM cultures presented increased resistance (from susceptibility to reduced susceptibility, from susceptibility to resistance, or from reduced susceptibility to resistance) to erythromycin (strains exposed to BZK, PAA and TSP), chloramphenicol (all compounds), tetracycline (BZK) and fosfomycin (all compounds). Regarding SA, after exposure its resistance to gentamicin (all compounds) and enrofloxacin (BZK, PAA and TSP) increased. The cell surface hydrophobicity (determined through the microbial adhesion to solvents -MATS- test) increased (LM exposed to PAA and TSP; SA exposed to BZK) or decreased (SA exposed to PAA) after contact with the biocides. These findings suggest that the use of biocides at subinhibitory concentrations can contribute to the increase in bacterial resistance to antibiotics, in addition to modifying the hydrophobicity of the cellular surface, which is related to the capacity of bacteria to form biofilm.

Serotyping, RAPD PCR, Antibiotic Susceptibility Profiling of Listeria spp. Isolated from Raw Chicken Meat

The present study was aimed at finding the prevalence, serotyping, RAPD and Setyping of Listeria monocytogenes in raw chicken meat purchased from different retail outlets and local butcher shops across the Nagpur city. Cultural examination of 100 raw poultry meat samples, revealed the prevalence of Listeria spp. (35 %). L. grayi was predominant (15 %) among the isolates followed by L. monocytogenes (12 %), L. welshimeri (5 %), L. innocua (2 %) and L. seeligeri (1%) respectively. Among the majority of strains of L. monocytogenes, virulence marker genes hlyA and iap, all together or in combination were detected. Serotyping PCR study revealed that all L. monocytogenes isolates to be serotype 4b, which is the major serotype involved in the human listeriosis. RAPD PCR analysis of L. monocytogenes isolates revealed two types of banding patterns. All 35 strains of Listeria showed in-vitro susceptibility to antibiotics like vancomycin (93.88 %) ceftriaxone + Tazobactum (92.71%) and moderate sensitivity to enrofloxacin (38.78 %), ceftriaxone (34.90%) and ampicillin (34.69 %). Whereas, all the isolates were least sensitive to erythromycine (6.49%) and sulphasomidine (4.08 %). All the Listeriae isolates were refractory to penicillin. The present findings indicate the presence of multiple drug resistance among L. monocytogenes and other Listeria spp. isolated from raw poultry meat samples. Potentially pathogenic L. monocytogenes isolates recovered from raw poultry meat samples also signifies the zoonotic potential of listeriosis in the local area of Nagpur. High prevalence of L. monocytogenes and other Listeria spp. in raw poultry meat and their sensitivity to the antibiotics tested, clearly indicates that vancomycin and ceftriaxone +tazobactam should be used as a drug of choice for treatment of listeriosis. Keywords: Serotyping PCR, RAPD, Antibiotic Sensitivity test, ceftriaxone, sulphasomidine, tazobactam

Effect of acidic conditions on the growth and expression of two virulence genes of Listeria monocytogenes serotype 4b

In this work, the effect of the usual acidic conditions of dry-cured fermented foods (pH values between 4.5 and 6), on the growth and expression of the virulence genes, hly and inlA, of Listeria monocytogenes serotype 4b, was evaluated. To analyse the expression of the inlA gene, a novel real-time PCR (qPCR) method using SYBR® Green methodology was developed. L. monocytogenes levels increased as the pH did and they were kept constant throughout incubation time at pH 4.5. However, a significant increase in the relative expression of the virulence genes was detected in most of the acidic conditions in all the incubation times. The most pronounced upregulation of the relative expression of the virulence genes was found at pH 4.5. The efficient inlA-based qPCR method could be of interest to check changes in the expression of such virulence gene of this pathogenic bacterium in acidic environments.

Design and 3D printing of an electrochemical sensor for Listeria monocytogenes detection based on loop mediated isothermal amplification

The aim of this work is the design and 3D printing of a new electrochemical sensor for the detection of Listeria monocytogenes based on loop mediated isothermal amplification (LAMP). The food related diseases involve a serious health issue all over the world. Listeria monocytogenes is one of the major problems of contaminated food, this pathogen causes a disease called listeriosis with a high rate of hospitalization and mortality. Having a fast, sensitive and specific detection method for food quality control is a must in the food industry to avoid the presence of this pathogen in the food chain (raw materials, facilities and products). A point-of-care biosensor based in LAMP and electrochemical detection is one of the best options to detect the bacteria on site and in a very short period of time. With the numerical analysis of different geometries and flow rates during sample injection in order to avoid bubbles, an optimized design of the microfluidic biosensor chamber was selected for 3D-printing and experimental analysis.For the electrochemical detection, a novel custom gold concentric-3-electrode consisting in a working electrode, reference electrode and a counter electrode was designed and placed in the bottom of the chamber. The LAMP reaction was optimized specifically for a primers set with a limit of detection of 1.25 pg of genomic DNA per reaction and 100% specific for detecting all 12 Listeria monocytogenes serotypes and no other Listeria species or food-related bacteria. The methylene blue redox-active molecule was tested as the electrochemical transducer and shown to be compatible with the LAMP reaction and very clearly distinguished negative from positive food samples when the reaction is measured at the end-point inside the biosensor.

Application of metabolomics analysis to aid in understanding the pathogenicity of different lineages and different serotypes of Listeria monocytogenes

Listeria monocytogenes is a foodborne pathogen with high mortality in young children, elderly persons, pregnant women, and immune-compromised individuals. Most human listeriosis cases are associated with four serotypes (1/2a, 1/2b, 1/2c and 4b) within lineages I and II. The intracellular metabolic changes in L. monocytogenes from different lineages and serotypes remain unclear. Here, a non-targeted metabolomics strategy, based on ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) coupled with chemometrics was performed to analyze the metabolic fluctuations in the lineages and serotypes of L. monocytogenes. In the aggregate, 93 L. monocytogenes isolates (two lineages and four serotypes) were investigated, and a total of 48 differential biomarker metabolites were identified. Twenty differential metabolites were observed at the lineage level, while the others were found at the serotype level. At the lineage level, significantly lower contents (fold change [FC] = 3.60) of γ-aminobutyric acid (GABA) was found in lineage II strains, as compared to lineage I strains. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment analysis showed that different substances between lineages I and II participated in multiple metabolic pathways, among which pyrimidine metabolism, purine metabolism, and aminoacyl-tRNA biosynthesis were significantly enriched. The major significantly upregulated (P < 0.05) metabolites, including uridine 5′-monophosphate, uridine, guanosine monophosphate, and guanosine, in lineage II strains affect the synthesis of DNA and RNA. At the serotype level, the upregulation of urea precursor substances produced by the purine metabolism pathway in serotype 4b strains may be one reason for the increased virulence of serotype 4b strains, compared to other serotype strains. In addition, the upregulation of pyridoxine in the vitamin B6 pathway in 4b strains was also observed. The differential metabolic pathway of 1/2a and 1/2c strains is nucleotide metabolism, which could lead to differences in the biosynthesis of DNA and RNA of the strain and further affect the growth and proliferation of strains.

Ecology of Listeria monocytogenes and Listeria species in India: the occurrence, resistance to biocides, genomic landscape and biocontrol.

Listeria monocytogenes, the causative agent of listeriosis, has been implicated in increasing foodborne outbreaks worldwide. The disease is manifested in various forms ranging from severe sepsis in immune-compromised individuals, febrile gastroenteritis, still birth, abortions and meningoencephalitis. In India, data from studies on the detection and molecular epidemiological analysis of L. monocytogenes are only recently emerging. The presence of Listeria in different ecological niches has been recorded from India, including foods, soil, vegetables, mangrove swamps, seafood, freshwater fishes, clinical cases, and also insects. The organism has also been isolated from women with spontaneous abortions, miscarriage or recurrent obstetric history, aborted foetuses, animal clinical cases and wildlife samples. A novel species of Listeria has also been characterized. Listeria monocytogenes strains isolated from clinical, environmental, and foods showed biofilm-forming abilities. Listeria monocytogenes serotype 4b isolates of ST328, a predominant and unique ST observed in India, was repeatedly isolated from different sources, times, and geographical locations. Here, we reviewed the occurrence of Listeria in different sources in India, its resistance to biocides, and provide epidemiological analysis on its genomic landscape.

Identification and serotyping of Listeria monocytogenes, isolated from various salmon products, sold in retail market in Lithuania.

Cold smoked salmon products (belly flaps, pieces, fillet, and loin) obtained from the retail market in Lithuania were tested for the presence of L. monocytogenes. It was found that contamination of the cold smoked fish products with Listeria spp. depends on the type of the product. Contamination with listeria in salmon belly flaps was 7.5 times higher than in the loin (P<0.05), 1.8 times higher than in the pieces (P<0.05) and 30 times higher than in the fillet (P<0.05). Microbiological analysis showed that 32.5% (P<0.05) of the fish product samples were infected with L. monocytogenes, while multiplex PCR confirmed 31.25% positive samples (P<0.01). According to the study results, L. monocytogenes strains were divided into two serotypes: 4b (94.6%) and 1/2a (5.4%). High contamination of the products with Listeria spp. showed that cold smoked salmon products, sold in local market, can be a reason of human listeriosis in Lithuania.

Phylogeny of the Bacillus altitudinis Complex and Characterization of a Newly Isolated Strain with Antilisterial Activity

Bacillus strain UTK D1-0055 was isolated from a laboratory environment and appeared to have antilisterial activity. The genome was sequenced, the strain was identified as Bacillus altitudinis, and a high-quality complete annotated genome was produced. The taxonomy was evaluated for this and related Bacillus species (B. aerophilus, B. pumilus, B. safensis, B. stratosphericus, and B. xiamenensis) because the taxonomy is unclear and contains errors in public databases such as NCBI. The included strains grouped into seven clusters based on average nucleotide identity. Strains designated as B. aerophilus, B. altitudinis, and B. stratosphericus grouped together in the cluster containing the B. altitudinis type strain, suggesting that these three species should be considered a single species, B. altitudinis. The antimicrobial activity of UTK D1-0055 was evaluated against a panel of 15 Listeria strains (nine Listeria monocytogenes serotypes, Listeria innocua, and Listeria marthii), other foodborne pathogens (six Salmonella enterica serotypes and Escherichia coli), and three representative fungi (Saccharomyces cerevisiae, Botrytis cinerea, and Hyperdermium pulvinatum). Antibacterial activity was observed against all Listeria strains, but no antibacterial effects were found against the other tested bacterial and fungal strains. Biosynthetic gene clusters were identified in silico that may be related to the observed antibacterial activity, and these clusters included genes that putatively encode bacteriocins and nonribosomally synthesized peptides. The B. altitudinis strain identified in this investigation had a broad range of antilisterial activity, suggesting that it and other related strains may be useful for biocontrol in the food industry.

Characterization of a Novel Group of Listeria Phages That Target Serotype 4b Listeria monocytogenes

Listeria monocytogenes serotype 4b strains are the most prevalent clinical isolates and are widely found in food processing environments. Bacteriophages are natural viral predators of bacteria and are a promising biocontrol agent for L. monocytogenes. The aims of this study were to characterize phages that specifically infect serotype 4b strains and to assess their ability to inhibit the growth of serotype 4b strains. Out of 120 wild Listeria phages, nine phages were selected based on their strong lytic activity against the model serotype 4b strain F2365. These nine phages can be divided into two groups based on their morphological characteristics and host range. Comparison to previously characterized phage genomes revealed one of these groups qualifies to be defined as a novel species. Phages LP-020, LP-027, and LP-094 were selected as representatives of these two groups of phages for further characterization through one-step growth curve and inhibition of serotype 4b L. monocytogenes experiments. Listeria phages that target serotype 4b showed an inhibitory effect on the growth of F2365 and other serotype 4 strains and may be useful for biocontrol of L.monocytogenes in food processing environments.

The Potential of Sun-Dried Grape Pomace as a Multi-Functional Ingredient for Herbal Infusion: Effects of Brewing Parameters on Composition and Bioactivity.

Wine and by-products are essential elements of a Mediterranean diet and considered as a reservoir of bioactive compounds with various health effects. Grape pomace, an easily available natural material of low cost, shares a similar wealth of health benefiting bioactive phytochemicals. The objective of this study was to explore the utilization of grape pomace from Commandaria dessert wine as main ingredient for functional infusions. Therefore, the ratio of water to grape pomace powder (40–200 mL g−1), infusion time (3–15 min) and temperature (55–95 °C) were optimized in terms of composition and bioactivity. Multiple response optimization indicated that brewing 200 mL water per g of material for 12.2 min at 95 °C, was the optimum method for preparing the infusion. Results also revealed a significant impact of three parameters as well as quadratic and interactive effects on composition and bioactivity of infusions. Furthermore, the infusion presents antimicrobial effects against Listeria monocytogenes serotypes and other common food pathogenic bacteria. Finally, a sensory evaluation was performed to assess the organoleptic attributes of the infusion and its improvement, with the addition of Mediterranean aromatic plants. Overall, the present work describes a promising strategy for the re-use of sun-dried grape pomace as a functional ingredient of infusions.

Prevalence of Listeria Species and Serotyping of Listeria monocytogenes Bacteria Isolated from Seafood Samples

Listeria species are well acknowledged as causal agents of human listeriosis with foodborne appearances. Seafoods are measured as the chief sources of Listeria spp. An existing survey was performed to apprise the incidence rate of Listeria spp. as well as distribution of pathogenic serotypes amongst the Listeria monocytogenes bacteria recovered from seafood samples. Three-hundred and fifty seafood samples were obtained and cultured. Listeria isolates were recognized using biochemical and PCR techniques. Distribution of 1/2a, 1/2b and 4b serotypes were examined using the PCR. Forty out of 350 (11.42%) samples harbored Listeria Spp. Incidence of L. monocytogenes, L. ivanovii and L. seeligeri were 62.50%, 20% and 7.50%, respectively. Incidence of Listeria spp. amongst the fish, shrimp, lobster and crab samples were 14%, 12%, 13% and 8%, respectively. Incidence of L. monocytogenes amongst the fish, shrimp, lobster and crab samples were 9%, 6%, 7% and 6%, respectively. Distribution of 1/2a, 1/2b and 4b serotypes were 48%, 28% and 8%, respectively. Discoveries disclosed the latent portion of seafoods as sources of Listeria spp. and alerted to health personnel regarding the requirement for appropriate management and cooking in persons that have recognized high-risk of developing food poisoning.

Occurrence, antimicrobial resistance, serotyping and virulence genes of Listeria monocytogenes isolated from foods

Listeria monocytogenes is a pathogen contaminated food, it is the cause of listeriosis worldwide. The aims of this study were to investigate the occurrence, antimicrobial resistance, serotyping and virulence genes of L. monocytogenes isolated from foods in Meknes city of Morocco. From June 2017 to May 2018, 520 food samples were randomly collected from a traditional market and two overcrowded popular neighborhoods (Lahdim and Hamria) and subjected to the detection of L. monocytogenes. Then, the antimicrobial susceptibility of the isolated strains were evaluated using the standard disk diffusion method and the determination of serotypes and virulence genes was performed by PCR. The results showed the detection of L. monocytogenes in fifteen (2.9%) of 520 samples, including three (5.7%) isolates in traditional whey, raw minced meat and raw sausage, two (3.8%) in raw milk and one (1.9%) in smen (traditional butter), raw bovine meat, raw poultry meat and raw fish, while salads and rayeb (traditional coagulated milk) were not contaminated. Among the fifteen isolated L. monocytogenes, nine (60%) belonged to the serogroup (1/2a, 1/2c, 3a and 3c), two (13.3%) belonged to the serogroup (1/2b, 3b, 4b and 4d) and four (26.6%) do not belong to any studied serogroup. Furthermore, fifteen (100%) isolates showed the presence of actA gene, fourteen (93.3%) harbored hlyA, prfA and plcB genes, thirteen (86.7%) carried inlA and inlC genes and twelve (80%) showed inlJ gene. The antimicrobial susceptibility analysis showed that the isolated strains were more resistant to amoxicillin/clavulanic acid (67.0%), erythromycin (60.0%), sulphamethoxazole (40.0%), ampicillin and sulphamethoxazole/trimethoprim (33.0%) and tetracycline (20.0%). Furthermore, 66.7% (10/15) were multidrug-resistant. From this study, we can conclude that foods marketed in Meknes city were contaminated by multidrug-resistant strains of L. monocytogenes harboring virulence genes, which may cause a serious risk to public health.

Cas12aFDet: A CRISPR/Cas12a-based fluorescence platform for sensitive and specific detection of Listeria monocytogenes serotype 4c

The CRISPR/Cas12a system has displayed remarkable potential in the development of new methods for nucleic acid detection owing to the trans-cleavage activity of Cas12a. Despite the tremendous development in recent years, existing CRISPR/Cas12a-based methods have several limitations such as the time-consuming process, which takes up to 2 h, and the risk of aerosol contamination during DNA amplicon transfer. Herein, we propose a CRISPR/Cas12a-based fluorescence detection platform named “Cas12aFDet” for rapid nucleic acid detection that overcomes these limitations. By integrating PCR or recombinase-aided amplification (RAA) methods with Cas12a-mediated cleavage in a sealed reaction tube, Cas12aFDet-based detection of amplified products could be accomplished within 15 min, while avoiding amplicon contamination. The detection limits of PCR-based Cas12aFDet and RAA-based Cas12aFDet were determined to be 3.37 × 101 cfu/mL and 1.35 × 102 cfu/mL of Listeria monocytogenes serotype 4c in pure culture, respectively. Most importantly, RAA-based Cas12aFDet exhibited 0.64 aM sensitivity for DNA detection, and showed high specificity for detection of other serotypes of Listeria and non-Listeria strains. Furthermore, the feasibility of the RAA-based Cas12aFDet method was evaluated in spiked and natural samples, enabling the quantitative detection of 1.35 × 108–1.35 × 103 cfu/g fresh grass carp of the target L. monocytogenes serotype 4c, and the results obtained for 22 natural aquatic samples were highly consistent with those of the culture-based serotyping method. The established Cas12aFDet platform is expected to provide a new paradigm for the sensitive and specific detection of pathogens in food safety and clinical diagnosis.

Complete Genome Sequence of a Serotype 7 Listeria monocytogenes Strain, FSL R9-0915.

Listeria monocytogenes serotype 7 lacks glycosidic constituents in wall teichoic acids. Here, we present the complete genome sequence of L. monocytogenes serotype 7 strain FSL R9-0915 and an analysis of genes known to affect L. monocytogenes antigenicity. This strain is used as a control strain in Listeria phage host range analyses.

Listeriosis Caused by Persistence of Listeria monocytogenes Serotype 4b Sequence Type 6 in Cheese Production Environment

Abstract A nationwide outbreak of human listeriosis in Switzerland was traced to persisting environmental contamination of a cheese dairy with Listeria monocytogenes serotype 4b, sequence type 6, cluster type 7488. Whole-genome sequencing was used to match clinical isolates to a cheese sample and to samples from numerous sites within the production environment.

Listeriosis Caused by Persistence of Listeria monocytogenes Serotype 4b Sequence Type 6 in Cheese Production Environment.

A nationwide outbreak of human listeriosis in Switzerland was traced to persisting environmental contamination of a cheese dairy with Listeria monocytogenes serotype 4b, sequence type 6, cluster type 7488. Whole-genome sequencing was used to match clinical isolates to a cheese sample and to samples from numerous sites within the production environment.

Mining of novel target genes through pan-genome analysis for multiplex PCR differentiation of the major Listeria monocytogenes serotypes

The abundant information provided by the pan-genome analysis approach reveals the diversity among Listeria monocytogenes serotypes. The objective of this study was to mine novel target genes using pan-genome analysis for multiplex PCR detection and differentiation of the major L. monocytogenes serotypes present in food. Pan-genome analysis and PCR validation revealed a total of 10 specific targets: one for lineage I, two for serogroup I.1, one for serogroup I.2, two for lineage II, one for serogroup II.1, three for lineage III. Primers for the novel targets were highly specific in individual reactions. The detection limits were 103–104 colony-forming units (CFU)/mL in pure bacterial cultures, meeting the requirements of molecular detection. Based on these novel targets, two new “lineage” multiplex PCR assays were developed to simultaneously distinguish between three lineages (I, II, and III) and five major serotypes (1/2a, 1/2b, 1/2c, 4b, and 4c) of L. monocytogenes. The detection limits of lineage I and lineage II&III mPCRs were 0.771 pg/μL and 1.76 pg/μL genomic DNA, respectively. The specificity of the mPCRs was robustly verified using other L. monocytogenes and non-L. monocytogenes serotypes. These results suggest that the two “lineage” multiplex PCRs based on novel targets offer a promising approach for accurate, sensitive, and rapid identification of L. monocytogenes serotypes.

Real-time PCR identification of Listeria monocytogenes serotype 4c using primers for novel target genes obtained by comparative genomic analysis

Detection of the foodborne pathogen Listeria monocytogenes serotype 4c, one of the predominant serotypes in aquatic products, is difficult and time-consuming. Our objective was to identify novel target genes for real-time PCR detection of L. monocytogenes serotype 4c using comparative genomics to facilitate its specific identification in food products. A total of 160 Listeria genome sequences, including those of 12 L. monocytogenes serotypes and 14 other Listeria species, were employed to identify serotype 4c-specific targets. Two serotype 4c-specific genes (SLCC2376_00062 and SLCC2376_00822) were obtained. Using primers for SLCC2376_00822, a real-time PCR assay for the detection of serotype 4c was developed. The specificty of this assay was robustly verified by other serotypes of L. monocytogenes and non-L. monocytogenes strains. In addition, this real-time PCR method could accurately detect serotype 4c even when mixed with different concentrations of serotypes 1/2a and 1/2b. Furthermore, the assay could successfully detect 1.4 × 109–1.4 × 103 CFU/g of L. monocytogenes serotype 4c in artificially contaminated grass carp without enrichment. These results demonstrate that the assay, which has high accuracy and sensitivity, comprises a promising approach for the detection and identification of L. monocytogenes serotype 4c strains in foods.

Forty years of peritoneal dialysis Listeria peritonitis: Case and review.

Infections with Listeria monocytogenes (LM) are very uncommon and severe especially in immunocompromised people. We report a continuous cycling peritoneal dialysis (CCPD) patient who presented initially disseminated listeriosis with peritonitis. He was successfully treated with intraperitoneal and intravenous ampicillin but died unfortunately from a cardiorespiratory arrest due to food inhalation. It is the 20th case of such peritonitis mentioned among PD patients and the first reported in Belgium. This case illustrates the importance of a systematic approach to get quick diagnosis and effective antibiotic readjustment. Empiric therapy is not effective on Listeria which is naturally resistant to cephalosporins and poorly sensitive to vancomycin. Ampicillin is the first-line antibiotic. In case of penicillin allergy, trimethoprim-sulfamethoxazole or erythromycin can be used successfully. Identification of LM serotype has a prognostic value. PD educative programmes should recommend to avoid unpasteurized dairy products to prevent listeriosis.