BACKGROUND Listeria monocytogenes(L. monocytogenes), a Gram-positive facultatively intracellular bacterium, is the causative agent of human listeriosis. Listeria infection is usually found in immunocompromised patient...BACKGROUND Listeria monocytogenes(L. monocytogenes), a Gram-positive facultatively intracellular bacterium, is the causative agent of human listeriosis. Listeria infection is usually found in immunocompromised patients, including elderly people, pregnant women, and newborns, whereas it is rare in healthy people. L.monocytogenes may cause meningitis, meningoencephalitis, and some very rare and severe complications, such as hydrocephalus and intracranial hemorrhage,which cause high mortality and morbidity worldwide. Up to now, reports on hydrocephalus and intracranial hemorrhage due to L. monocytogenes are few.CASE SUMMARY We herein report a case of rhombencephalitis caused by L. monocytogenes in a 29-year-old man. He was admitted to the hospital with a 2-d history of headache and fever. He consumed unpasteurized cooked beef two days before appearance.His medical history included type 2 diabetes mellitus, and contaminated beef intake 2 d before onset. Cerebrospinal fluid analysis revealed Gram-positive rod infection, and blood culture was positive for L. monocytogenes. Magnetic resonance imaging findings suggested rhombencephalitis and hydrocephalus.Treatment was started empirically and then modified according to the blood culture results. Repeated CT images were suggestive of intracranial hemorrhage.Although the patient underwent aggressive external ventricular drainage, he died of a continuing deterioration of intracranial conditions.CONCLUSION Hydrocephalus, intracranial hemorrhage, and inappropriate antimicrobial treatment are the determinations of unfavorable outcomes.展开更多
Listeria monocytogenes is an important foodborne pathogen responsible for listeriosis,a fatal disease.It is widely distributed in various foods and environmental sources.In this review,we focused on addressing PCR-bas...Listeria monocytogenes is an important foodborne pathogen responsible for listeriosis,a fatal disease.It is widely distributed in various foods and environmental sources.In this review,we focused on addressing PCR-based technologies,including conventional PCR,qPCR and droplet digital PCR(ddPCR).Specifically,we described(a)conventional PCR and mono-,duplex-and multiplex-qPCR methodologies;(b)development and applications of gene HlyA-,Iap-,PrfA–and SsrA-based conventional and qPCR assays as well as PCR assays targeting newly identified gene targets for specific detection of L.monocytogenes;differentiation of viable from dead L.monocytogenes by qPCR in conjugation with propidium monoazide pretreatment;PCR-based serotype identification of L.monocytogenes isolates;PCR-based detection of L.ivanovii,infecting ruminants,differentiation of L.monocytogenes from other Listeria species;and sigB-gene based PCR identification of Listeria spp;(c)applications of ddPCR in detection of L.monocytogenes;and(d)application of qPCR assays in detection and subtyping of L.monocytogenes in milk and dairy products;meats,meat products and meat-processing environment;and seafood,seafood products and processing environment.Our goal was to provide a relatively comprehensive overview of PCR-based methodologies available in detection,characterization and subtyping of various strains of L.monocytogenes in foods and environmental sources.展开更多
Listeria monocytogenes,one of the most important foodborne pathogens,can cause listeriosis,a lethal disease for humans.L.ivanovii,which is closely related to L.monocytogenes,is also widely distributed in nature and in...Listeria monocytogenes,one of the most important foodborne pathogens,can cause listeriosis,a lethal disease for humans.L.ivanovii,which is closely related to L.monocytogenes,is also widely distributed in nature and infects mainly warm-blooded ruminants,causing economic loss.Thus,there are high priority needs for methodologies for rapid,specific,cost-effective and accurate detection,characterization and subtyping of L.monocytogenes and L.ivanovii in foods and environmental sources.In this review,we(A)described L.monocytogenes and L.ivanovii,world-wide incidence of listeriosis,and prevalence of various L.monocytogenes strains in food and environmental sources;(B)comprehensively reviewed different types of traditional and newly developed methodologies,including culture-based,antigen/antibody-based,LOOP-mediated isothermal amplification,matrix-assisted laser desorption ionization-time of flight-mass spectrometry,DNA microarray,and genomic sequencing for detection and characterization of L.monocytogenes in foods and environmental sources;(C)comprehensively summarized different subtyping methodologies,including pulsed-field gel electrophoresis,multi-locus sequence typing,ribotyping,and phage-typing,and whole genomic sequencing etc.for subtyping of L.monocytogenes strains from food and environmental sources;and(D)described the applications of these methodologies in detection and subtyping of L.monocytogenes in foods and food processing facilities.展开更多
Aptamers are specific nucleic acid sequences that can bind to a wide range of nucleic acid and non-nucleic acid targets with high affinity and specificity. Nucleic acid aptamers are selected in vitro from single stran...Aptamers are specific nucleic acid sequences that can bind to a wide range of nucleic acid and non-nucleic acid targets with high affinity and specificity. Nucleic acid aptamers are selected in vitro from single stranded DNA or RNA ligands containing random sequences of up to a few hundred nucleotides. Systematic evolution of ligands by exponential enrichment （SELEX） was used to select and PCR amplify DNA sequences （aptamers） capable of binding to and detecting Listeria monocytogenes, one of the major food-borne pathogens. A simplified affinity separation approach was employed, in which L. monocytogenes in exponential （log） phase of growth was used as the separation target. A fluorescently-labeled aptamer assay scheme was devised for detecting L. monoeytogenes. This report described a novel approach to the detection of L. monocytogenes using DNA aptamers. Aptamers were developed by nine rounds of SELEX. A high affinity aptamer was successfully selected from the initial random DNA pool, and its secondary structure was also investigated. One of aptamers named e01 with the highest affinity was further tested in aptamer-peroxidase and aptamer-fluorescence staining protocols. This study has proved the principle that the whole-cell SELEX could be a promising technique to design aptamer-based molecular probes for dectection of pathogenic microorganisms without tedious isolation and purification of complex markers or targets.展开更多
Listeriosis is caused by Listeria monocytogenes(LM) and is currently considered to be one of the leading food-borne diseases worldwide, with mortality rate of 20%~30%. Currently, detection methods for LM are time-cons...Listeriosis is caused by Listeria monocytogenes(LM) and is currently considered to be one of the leading food-borne diseases worldwide, with mortality rate of 20%~30%. Currently, detection methods for LM are time-consuming with low sensitivity, and delayed detection results. SYTO9 has a high affinity for DNA and exhibits enhanced fluorescence upon binding. Therefore, this study used SYTO9 staining and image processing to develop a rapid loop mediated isothermal amplification(LAMP) detection method for LM. Smartphone was successfully used for detecting the color change in different concentrations of LM. Besides, the optimized LAMP reaction temperature was 63 °C by color identification, and the limit of detection for LM was 6 copies/μL in the green channel. So, the developed method, based on image processing, is simple, sensitive and rapid, which provides a new idea and method for rapid detection of LM and other food-borne bacterial pathogens.展开更多
Listeria monocytogenes is an important zoonotic foodborne pathogen that can tolerate a number of environmental stresses. Rsb R, an upstream regulator of the sigma B(Sig B) factor, is thought to sense environmental cha...Listeria monocytogenes is an important zoonotic foodborne pathogen that can tolerate a number of environmental stresses. Rsb R, an upstream regulator of the sigma B(Sig B) factor, is thought to sense environmental challenges and trigger the SigB pathway. In Bacillus subtilis, two phosphorylation sites in RsbR are involved in activating the SigB pathway and a feedback mechanism, respectively. In this study, the role of RsbR in L. monocytogenes under mild and severe stresses was investigated. Strains with genetic deletion(Δrsb R), complementation(C-Δrsb R), and phosphorylation site mutations in the rsbR(RsbR-T175 A, RsbR-T209 A, and RsbR-T175 A-T209 A) were constructed to evaluate the roles of these RsbR sequences in listerial growth and survival. SigB was examined at the transcriptional and translational levels. Deletion of rsb R reduced listerial growxth and survival in response to acidic stress. Substitution of the phosphorylation residue RsbR-T175 A disabled RsbR complementation, while RsbR-T209 A significantly upregulated SigB expression and listerial survival. Our results provide clear evidence that two phosphorylation sites of Rsb R are functional in L. monocytogenes under acidic conditions, similar to the situation in B. subtilis.展开更多
We aimed to investigate the potential pathogenic profile and antibiotic resistance of Listeria monocytogenes isolated from ready-to-eat food in China.Antimicrobial resistance was determined by broth microdilution foll...We aimed to investigate the potential pathogenic profile and antibiotic resistance of Listeria monocytogenes isolated from ready-to-eat food in China.Antimicrobial resistance was determined by broth microdilution following the Clinical and Laboratory Standards Institute protocol Molecular serotyping,virulence,and resistance genes were identified using PCR.Multi-locus展开更多
Near-infrared spectra of pathogenic bacteria (salmonella and Listeria monocytogenes ) were determined, and the spectral data were analyzed by the projection discriminant analysis based on principal component analysis ...Near-infrared spectra of pathogenic bacteria (salmonella and Listeria monocytogenes ) were determined, and the spectral data were analyzed by the projection discriminant analysis based on principal component analysis (PCA). The expected results were obtained. The results showed that salmonella and L. monocytogenes could be distinguished from each other by the near-infrared spectroscopy of the whole cells, cell walls or cytoplasm.展开更多
This study was aimed to determine sufficient frying time to reduce the number of Listeria monocytogenes present in chicken burger patties to non-detectable level which is fit for human consumption. Commercially availa...This study was aimed to determine sufficient frying time to reduce the number of Listeria monocytogenes present in chicken burger patties to non-detectable level which is fit for human consumption. Commercially available chicken burger patties were artificially contaminated with L. monocytogenes at level of approximately 9 log CFU/ml. The contaminated chicken burger patties were cooked for 0, 2, 4, 5, 8, and 10 minutes to determine survival of L. monocyto-genes. Results demonstrated a linear correlation between mean log reduction of L. monocytogenes and frying time. L. monocytogenes was not detected in chicken burger patties that were cooked for 6 minutes and above. As a result from this study, it is suggested that a minimum frying time for burger patties is 6 minutes. This can be treated as a safety measure to avoid consequences of consumption of undercooked burger patties.展开更多
The objective of this study was to determine the effect of sodium lactate on the survival of Listeria monocytogenes, Escherichia coli O157: H7, and Salmonella spp. in cooked ham during storage at refrigerated and abus...The objective of this study was to determine the effect of sodium lactate on the survival of Listeria monocytogenes, Escherichia coli O157: H7, and Salmonella spp. in cooked ham during storage at refrigerated and abuse temperatures. Cooked ham was added with 0% - 3% lactate, inoculated with a multiple-strain mixture of L. monocytogenes, E. coli O157: H7, or Salmonella spp. and stored at 4oC - 15oC for up to 35 day. The growth of the three pathogens was inhibited in ham containing 3% lactate, and no growth of E. coli O157: H7 and Salmonella spp. occurred at the lowest storage tem- peratures of 6 and 8oC, respectively. In ham containing no lactate, the average growth rates were 0.256 - 0.380 log CFU/day for L. monocytogenes at 4oC - 8oC, 0.242 - 0.315 log CFU/day for E. coli O157: H7 at 8oC - 15oC, and 0.249 - 0.328 log CFU/day for Salmonella spp. at 10oC - 15oC. The addition of 1% or 2% lactate significantly (P < 0.05) reduced the growth rates of the three pathogens, and the effect was more profound at lower temperatures. Salmonella spp. were more sensitive to the effect of lactate than L. monocytogenes and E. coli O157: H7. Polynomial models were developed to describe the growth rates of the three pathogens as affected by the lactate concentration and storage tem- perature. Results from this study demonstrate the effect of lactate on the growth of L. monocytogenes, E. coli O157: H7, and Salmonella spp. in cooked ham and indicate the effective lactate concentrations and storage temperatures that can be used to enhance the microbiological safety of ready-to-eat ham products.展开更多
[Objective] This study aimed to detect the reliability of LAMP method for detecting Listeria monocytogenes in dairy food. [Method] Based on the sequence of hlyA gene encoding listeriolysin O in Listeria monocytogenes,...[Objective] This study aimed to detect the reliability of LAMP method for detecting Listeria monocytogenes in dairy food. [Method] Based on the sequence of hlyA gene encoding listeriolysin O in Listeria monocytogenes, the LAMP method was established for detecting Listeria monocytogenes in dairy food. [Result] The es- tablished LAMP rapid detection method has .high specificity and sensitivity, which are equivalent to those of real-time fluorescent quantitative PCR. The detection re- sults of Listeria monocytogenes in dairy food by established LAMP method were completely consistent with those by bacterial isolation method. [Conclusion] The de- tection results of Listeria monocytogenes by LAMP method can be directly identified by naked eye, so the established LAMP method was suitable for the detection of Listeria monocytogenes in dairy food in emergency situations.展开更多
Listeria monocytogenes is the pathogen of listeriosis and it causes severe infections like septicemia, encephalitis, and meningitis, especially in immunocompromised individuals, newborns, and pregnant women. Its wide ...Listeria monocytogenes is the pathogen of listeriosis and it causes severe infections like septicemia, encephalitis, and meningitis, especially in immunocompromised individuals, newborns, and pregnant women. Its wide distribution in the environment and ability to survive or even grow under adverse conditions has made L. monocytogenes an important public health concern and in food industry.展开更多
Listeria monocytogenes is a worrisome food-borne pathogen threatening global food safety.Our previous study proved that lipopeptide brevilaterin B showed efficient antibacterial activity against L.monocytogenes by int...Listeria monocytogenes is a worrisome food-borne pathogen threatening global food safety.Our previous study proved that lipopeptide brevilaterin B showed efficient antibacterial activity against L.monocytogenes by interacting with the cell membrane.This research further explored the antibacterial mechanism of brevilaterin B against L.monocytogenes at the sub-minimum inhibition concentration via transcriptomic analysis.Brevilaterin B induced growth inhibition rather than direct membrane lysis in L.monocytogenes at the minimum inhibitory concentration.Transcriptomic analysis showed 1779 difference expressed genes,including 895 up-regulated and 884 down-regulated genes.Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis indicated that brevilaterin B influenced multiple pathways of L.monocytogenes,including peptidoglycan biosynthesis,membrane transport(ATP-binding cassette transports,ion transport),cellular metabolism(amino acid and lipid metabolism),ATP synthesis,and activation of the stress response(quorum sensing and bacterial chemotaxis).In conclusion,brevilaterin B affects gene expression related to biosynthesis,transport and stress response pathways on the membrane of L.monocytogenes.The present work provides the first transcriptomic assessment of the antibacterial mechanism of lipopeptide brevilaterin B at the gene level.展开更多
BACKGROUNDIntracranial Listeria infections are common in newborns and immunocompromisedindividuals, but brainstem abscesses are rare.CASE SUMMARYWe report a rare case of brainstem abscesses caused by Listeria monocyto...BACKGROUNDIntracranial Listeria infections are common in newborns and immunocompromisedindividuals, but brainstem abscesses are rare.CASE SUMMARYWe report a rare case of brainstem abscesses caused by Listeria monocytogenes in apreviously healthy adult patient. The patient’s magnetic resonance imagingexamination showed multiple brain abscesses, and his second cerebrospinal fluidculture test indicated the presence of Listeria monocytogenes. Despite earlyempirical therapy, the patient’s condition progressively deteriorated. Because thepatient's abscesses were located in the brainstem and multiple lobes, surgery wasnot possible. The patient died 40 d after admission.CONCLUSIONThis case highlights the importance of rational clinical use of drugs to avoidpotentially serious infectious complications.展开更多
Listeria monocytogenes(LM),a Gram-positive facultative intracellular bacterium,can be used as an effective exogenous antigen expression vector in tumor-target therapy.But for successful clinical application,it is nece...Listeria monocytogenes(LM),a Gram-positive facultative intracellular bacterium,can be used as an effective exogenous antigen expression vector in tumor-target therapy.But for successful clinical application,it is necessary to construct attenuated LM stain that is safe yet retains the potency of LM based on the full virulent pathogen.In this study,attenuated LM and recombinants of LM expressing melanoma inhibitory activity(MIA) were constructed successfully.The median lethal dose(LD 50) and invasion efficiency of attenuated LM strains were detected.The recombinants were utilized for immunotherapy of animal model of B16F10 melanoma.The level of MIA mRNA expression in tumor tissue was detected by using real-time polymerase chain reaction(PCR) with specific sequence,meanwhile the anti-tumor immune response was assayed by flow cytometric analysis and enzyme-linked immunosorbent spot(ELISPOT) assay.The results showed the toxicity and invasiveness of attenuated LM were decreased as compared with LM,and attenuated LM expressing MIA,especially the double-genes attenuated LM recombinant,could significantly induce anti-tumor immune response and inhibit tumor growth.This study implicates attenuated LM may be a safer and more effective vector for immunotherapy of melanoma.展开更多
Much progress of application of bacterial vaccine in treatment and prevention of tumor was acquired,which showed broad prospect in clinical study of animals and humans. Listeria monocytogenes( L. monocytogenes) was co...Much progress of application of bacterial vaccine in treatment and prevention of tumor was acquired,which showed broad prospect in clinical study of animals and humans. Listeria monocytogenes( L. monocytogenes) was considered much important by virtue of its special characteristic of biology and immunology.L. monocytogenes was ingested by professional or part-time phagocytes,survived and proliferated in the phagocytes under synergism of toxic factor secreted by itself,meanwhile,the cellular and humoral immune response was induced. Antigenic gene of specific tumor was loaded in the attenuated L. monocytogenes,which can enhance immune response of host cells. Effective cell targeted to enter tumor tissue and acted on tumor cells to induce apoptosis of tumor cells. Tumor degenerated not easy to reappear. Therefore,recombinant attenuated L. monocytogenes was a safe and effective anti-cancer vaccine vector. Now the work of researchers mainly focuses on solving practical problem in clinical application. Biological characteristics of L. monocytogenes,feasibility and superiority of L. monocytogenes as targeted vaccine vector,problem and prospect of L. monocytogenes in clinical application of anti-tumor were reviewed in this paper.展开更多
A bacteriocin producing strain of Lactococcus lactis subsp. lactis LABW4 was isolated from naturally fermented milk product which exhibited strong antibacterial activity against Listeria monocytogenes MTCC657, a food ...A bacteriocin producing strain of Lactococcus lactis subsp. lactis LABW4 was isolated from naturally fermented milk product which exhibited strong antibacterial activity against Listeria monocytogenes MTCC657, a food spoilage psychrophilic organism. Both cell free and heat killed supernatants of LABW4 were effective to produce zones of inhibition against L. monocytogenes in vitro. The antibacterial metabolite(s) of LABW4 showed strong cidal effect on the growth of L. monocytogenes. Meat samples, mixed with heat killed supernatant of LABW4 when inoculated with Listeria, remain fresh up to 25 days in refrigerated condition whereas spoilage started immediately after 24 hours of inoculation for control sets. Enhancement of Lactate dehydrogenase of L. monocytogenes upon treatment with LABW4 cell free supernatant suggested its lytic mode of action. Cell lysis or degradations were also supported by scanning electron micrograph of treated cells.展开更多
Floor drains in processing environments harbor Listeria spp. due to continuous presence of humidity and organic substrates. Cleaning and washing activities in food-processing facilities can translocate the bacterial c...Floor drains in processing environments harbor Listeria spp. due to continuous presence of humidity and organic substrates. Cleaning and washing activities in food-processing facilities can translocate the bacterial cells from the drain to the surrounding environment, thus contaminating food products still in production. This study evaluated the potential for translocation of Listeria monocytogenes from drains to food contact surfaces in the surrounding environment using Listeria innocua as a surrogate. A 7 × 7 × 8-foot polycarbonate flexi-glass chamber with a 10-inch-diameter drain mounted on an aluminum cabinet was used. Stainless steel coupons (6.4 × 1.9 × 0.1 cm, 12 per height) were hung at 1, 3, and 5 feet inside the chamber. Four treatment sets;non-inoculated, non-treated;non-inoculated, treated;inoculated, treated;inoculated non-treated;and two subtreatments of 8 h and 48 h were performed. For the inoculated sets, meat slurry (10 gof ground beef in 900 mL water) and a four-strain cocktail of Listeria innocua at 7 - 8 log CFU/mL were used. For the treated sets, in addition, a commercial cleaner and sanitizer was applied. The drain was cleaned using a pressure hose (40 - 50 psi) after 8 h and 48 h. Coupons were then removed and enriched in listeria enrichment broth to establish if any cell translocated from the drain onto the stainless steel coupons via aerosols generated during washing. Confirmation was done using VIP Listeria rapid test kits. Results indicated translocation at all three heights ranging from 2% - 25%. Significantly higher translocation (p Listeria spp. from drains to food contact surfaces does occur and increases with increased proximity to the drain.展开更多
Rapid identification and characterization of Listeria monocytogenes are required for the food industry, epidemiological studies, and disease prevention and control. However, typing procedures are labor-intensive and t...Rapid identification and characterization of Listeria monocytogenes are required for the food industry, epidemiological studies, and disease prevention and control. However, typing procedures are labor-intensive and time-consuming, and they require technical expertise, a panel of sera and reference culture strains or sophisticated and expensive equipment. To improve upon traditional diagnostic methods for L. monocytogenes we developed and evaluated an efficient procedure for the specific identification of L. monocytogenes and the major pathogenic serotypes of the species based on loop-mediated isothermal amplification (LAMP). Four individual reactions were designed using primers targeting any L. monocytogenes serotypes (LAMP-AS) and the 1/2a (LAMP-1/2a), 1/2b (LAMP-1/2b), and 4b (LAMP-4b) serotypes. The procedure distinguished L. monocytogenes from closely genetically related species and the targeted serotypes. Cross-reactivity with a few rare serotypes isolated from food or clinical samples did not impair the usefulness of the procedure. Thus, our approach constitutes a fast, easy and low-cost alternative for L. monocytogenes diagnosis and serotyping and may be useful for surveillance and epidemiological investigation programs.展开更多
Contamination of food with spoilage bacteria and pathogens from food processing environment remains a challenge for the food industry. Bacteria able to persist in such environments over time must survive several hygie...Contamination of food with spoilage bacteria and pathogens from food processing environment remains a challenge for the food industry. Bacteria able to persist in such environments over time must survive several hygienic hurdles. The aim of this study was to identify bacteria surviving practical disinfection and compare their survival abilities with representative isolates of the pathogen Listeria monocytogenes. Bacteria isolated from processing surfaces after cleaning and disinfection in a meat abattoir were identified. Selected isolates of the most frequently isolated bacterial genera along with eight meat associated L. monocytogenes were further characterized with regard to biofilm formation abilities at 12℃ and 20℃, tolerance to desiccation (stainless steel at 70% RH at 12℃) and bactericidal effects of recommended in-use-concentrations of four commercial disinfectants on stainless steel surface. The most dominating bacterial genera based on counts on non-selective agar were Aerococcus, Acinetobacter, Pseudomonas, Serratia and Staphylococcus. Isolates of Citrobacter. Enterobacter and Serratia dominated on agar plates selective for Enterobacteriaceae. In general, Gram negative bacteria formed more biofilm than Gram positives, especially at 12℃ with the best biofilm formers being Acinetobacter, Citrobacter and Pseudomonas. Listeria monocytogenes were poor biofilm formers. Gram positives survived better air drying than Gram negatives. Strains of L. monocytogenes were more sensitive to desiccation than the other Gram positives;Aerococcus, Kocuria and Staphylococcus. Two disinfectants containing peracetic acid and a disinfectant containing alkylaminoacetate had limited or no antibacterial effect against bacteria dried on stainless steel. A quaternary ammonium compound-based disinfectant provided >2 log reductions of Aerococcus, Acinetobacter and Listeria. Only 0.5 log reductions were obtained against Staphylococcus and no bactericidal effect against Serratia. In this study the dominating flora in a meat abattoir was isolated and identified. Several of these bacteria were better biofilm formers and more resistant to desiccation and disinfection than L. monocytogenes. The disinfectants tested had limited bactericidal activity against surface associated bacteria.展开更多
基金Young Teacher Foundation of Wuhan University,China,No.2042017kf0142Guidance Fund of Renmin Hospital of Wuhan University,China,No.RMYD2018M19
文摘BACKGROUND Listeria monocytogenes(L. monocytogenes), a Gram-positive facultatively intracellular bacterium, is the causative agent of human listeriosis. Listeria infection is usually found in immunocompromised patients, including elderly people, pregnant women, and newborns, whereas it is rare in healthy people. L.monocytogenes may cause meningitis, meningoencephalitis, and some very rare and severe complications, such as hydrocephalus and intracranial hemorrhage,which cause high mortality and morbidity worldwide. Up to now, reports on hydrocephalus and intracranial hemorrhage due to L. monocytogenes are few.CASE SUMMARY We herein report a case of rhombencephalitis caused by L. monocytogenes in a 29-year-old man. He was admitted to the hospital with a 2-d history of headache and fever. He consumed unpasteurized cooked beef two days before appearance.His medical history included type 2 diabetes mellitus, and contaminated beef intake 2 d before onset. Cerebrospinal fluid analysis revealed Gram-positive rod infection, and blood culture was positive for L. monocytogenes. Magnetic resonance imaging findings suggested rhombencephalitis and hydrocephalus.Treatment was started empirically and then modified according to the blood culture results. Repeated CT images were suggestive of intracranial hemorrhage.Although the patient underwent aggressive external ventricular drainage, he died of a continuing deterioration of intracranial conditions.CONCLUSION Hydrocephalus, intracranial hemorrhage, and inappropriate antimicrobial treatment are the determinations of unfavorable outcomes.
文摘Listeria monocytogenes is an important foodborne pathogen responsible for listeriosis,a fatal disease.It is widely distributed in various foods and environmental sources.In this review,we focused on addressing PCR-based technologies,including conventional PCR,qPCR and droplet digital PCR(ddPCR).Specifically,we described(a)conventional PCR and mono-,duplex-and multiplex-qPCR methodologies;(b)development and applications of gene HlyA-,Iap-,PrfA–and SsrA-based conventional and qPCR assays as well as PCR assays targeting newly identified gene targets for specific detection of L.monocytogenes;differentiation of viable from dead L.monocytogenes by qPCR in conjugation with propidium monoazide pretreatment;PCR-based serotype identification of L.monocytogenes isolates;PCR-based detection of L.ivanovii,infecting ruminants,differentiation of L.monocytogenes from other Listeria species;and sigB-gene based PCR identification of Listeria spp;(c)applications of ddPCR in detection of L.monocytogenes;and(d)application of qPCR assays in detection and subtyping of L.monocytogenes in milk and dairy products;meats,meat products and meat-processing environment;and seafood,seafood products and processing environment.Our goal was to provide a relatively comprehensive overview of PCR-based methodologies available in detection,characterization and subtyping of various strains of L.monocytogenes in foods and environmental sources.
文摘Listeria monocytogenes,one of the most important foodborne pathogens,can cause listeriosis,a lethal disease for humans.L.ivanovii,which is closely related to L.monocytogenes,is also widely distributed in nature and infects mainly warm-blooded ruminants,causing economic loss.Thus,there are high priority needs for methodologies for rapid,specific,cost-effective and accurate detection,characterization and subtyping of L.monocytogenes and L.ivanovii in foods and environmental sources.In this review,we(A)described L.monocytogenes and L.ivanovii,world-wide incidence of listeriosis,and prevalence of various L.monocytogenes strains in food and environmental sources;(B)comprehensively reviewed different types of traditional and newly developed methodologies,including culture-based,antigen/antibody-based,LOOP-mediated isothermal amplification,matrix-assisted laser desorption ionization-time of flight-mass spectrometry,DNA microarray,and genomic sequencing for detection and characterization of L.monocytogenes in foods and environmental sources;(C)comprehensively summarized different subtyping methodologies,including pulsed-field gel electrophoresis,multi-locus sequence typing,ribotyping,and phage-typing,and whole genomic sequencing etc.for subtyping of L.monocytogenes strains from food and environmental sources;and(D)described the applications of these methodologies in detection and subtyping of L.monocytogenes in foods and food processing facilities.
文摘Aptamers are specific nucleic acid sequences that can bind to a wide range of nucleic acid and non-nucleic acid targets with high affinity and specificity. Nucleic acid aptamers are selected in vitro from single stranded DNA or RNA ligands containing random sequences of up to a few hundred nucleotides. Systematic evolution of ligands by exponential enrichment （SELEX） was used to select and PCR amplify DNA sequences （aptamers） capable of binding to and detecting Listeria monocytogenes, one of the major food-borne pathogens. A simplified affinity separation approach was employed, in which L. monocytogenes in exponential （log） phase of growth was used as the separation target. A fluorescently-labeled aptamer assay scheme was devised for detecting L. monoeytogenes. This report described a novel approach to the detection of L. monocytogenes using DNA aptamers. Aptamers were developed by nine rounds of SELEX. A high affinity aptamer was successfully selected from the initial random DNA pool, and its secondary structure was also investigated. One of aptamers named e01 with the highest affinity was further tested in aptamer-peroxidase and aptamer-fluorescence staining protocols. This study has proved the principle that the whole-cell SELEX could be a promising technique to design aptamer-based molecular probes for dectection of pathogenic microorganisms without tedious isolation and purification of complex markers or targets.
基金supported by the grant from the National Natural Science Foundation of China (Nos. 61901168, 8200240581902153)+1 种基金Zhuzhou Innovative City Construction Project(No. 2020–020)China Postdoctoral Science Foundation (No.2018M630498)。
文摘Listeriosis is caused by Listeria monocytogenes(LM) and is currently considered to be one of the leading food-borne diseases worldwide, with mortality rate of 20%~30%. Currently, detection methods for LM are time-consuming with low sensitivity, and delayed detection results. SYTO9 has a high affinity for DNA and exhibits enhanced fluorescence upon binding. Therefore, this study used SYTO9 staining and image processing to develop a rapid loop mediated isothermal amplification(LAMP) detection method for LM. Smartphone was successfully used for detecting the color change in different concentrations of LM. Besides, the optimized LAMP reaction temperature was 63 °C by color identification, and the limit of detection for LM was 6 copies/μL in the green channel. So, the developed method, based on image processing, is simple, sensitive and rapid, which provides a new idea and method for rapid detection of LM and other food-borne bacterial pathogens.
基金Project supported by the National Natural Science Foundation of China(Nos.31702250 and 31600292)the Open Fund Project by Key Laboratory of Animal Preventive Medicine of Zhejiang Province(No.ZPKLPVM2017KFKT001),China
文摘Listeria monocytogenes is an important zoonotic foodborne pathogen that can tolerate a number of environmental stresses. Rsb R, an upstream regulator of the sigma B(Sig B) factor, is thought to sense environmental challenges and trigger the SigB pathway. In Bacillus subtilis, two phosphorylation sites in RsbR are involved in activating the SigB pathway and a feedback mechanism, respectively. In this study, the role of RsbR in L. monocytogenes under mild and severe stresses was investigated. Strains with genetic deletion(Δrsb R), complementation(C-Δrsb R), and phosphorylation site mutations in the rsbR(RsbR-T175 A, RsbR-T209 A, and RsbR-T175 A-T209 A) were constructed to evaluate the roles of these RsbR sequences in listerial growth and survival. SigB was examined at the transcriptional and translational levels. Deletion of rsb R reduced listerial growxth and survival in response to acidic stress. Substitution of the phosphorylation residue RsbR-T175 A disabled RsbR complementation, while RsbR-T209 A significantly upregulated SigB expression and listerial survival. Our results provide clear evidence that two phosphorylation sites of Rsb R are functional in L. monocytogenes under acidic conditions, similar to the situation in B. subtilis.
文摘We aimed to investigate the potential pathogenic profile and antibiotic resistance of Listeria monocytogenes isolated from ready-to-eat food in China.Antimicrobial resistance was determined by broth microdilution following the Clinical and Laboratory Standards Institute protocol Molecular serotyping,virulence,and resistance genes were identified using PCR.Multi-locus
文摘Near-infrared spectra of pathogenic bacteria (salmonella and Listeria monocytogenes ) were determined, and the spectral data were analyzed by the projection discriminant analysis based on principal component analysis (PCA). The expected results were obtained. The results showed that salmonella and L. monocytogenes could be distinguished from each other by the near-infrared spectroscopy of the whole cells, cell walls or cytoplasm.
文摘This study was aimed to determine sufficient frying time to reduce the number of Listeria monocytogenes present in chicken burger patties to non-detectable level which is fit for human consumption. Commercially available chicken burger patties were artificially contaminated with L. monocytogenes at level of approximately 9 log CFU/ml. The contaminated chicken burger patties were cooked for 0, 2, 4, 5, 8, and 10 minutes to determine survival of L. monocyto-genes. Results demonstrated a linear correlation between mean log reduction of L. monocytogenes and frying time. L. monocytogenes was not detected in chicken burger patties that were cooked for 6 minutes and above. As a result from this study, it is suggested that a minimum frying time for burger patties is 6 minutes. This can be treated as a safety measure to avoid consequences of consumption of undercooked burger patties.
文摘The objective of this study was to determine the effect of sodium lactate on the survival of Listeria monocytogenes, Escherichia coli O157: H7, and Salmonella spp. in cooked ham during storage at refrigerated and abuse temperatures. Cooked ham was added with 0% - 3% lactate, inoculated with a multiple-strain mixture of L. monocytogenes, E. coli O157: H7, or Salmonella spp. and stored at 4oC - 15oC for up to 35 day. The growth of the three pathogens was inhibited in ham containing 3% lactate, and no growth of E. coli O157: H7 and Salmonella spp. occurred at the lowest storage tem- peratures of 6 and 8oC, respectively. In ham containing no lactate, the average growth rates were 0.256 - 0.380 log CFU/day for L. monocytogenes at 4oC - 8oC, 0.242 - 0.315 log CFU/day for E. coli O157: H7 at 8oC - 15oC, and 0.249 - 0.328 log CFU/day for Salmonella spp. at 10oC - 15oC. The addition of 1% or 2% lactate significantly (P < 0.05) reduced the growth rates of the three pathogens, and the effect was more profound at lower temperatures. Salmonella spp. were more sensitive to the effect of lactate than L. monocytogenes and E. coli O157: H7. Polynomial models were developed to describe the growth rates of the three pathogens as affected by the lactate concentration and storage tem- perature. Results from this study demonstrate the effect of lactate on the growth of L. monocytogenes, E. coli O157: H7, and Salmonella spp. in cooked ham and indicate the effective lactate concentrations and storage temperatures that can be used to enhance the microbiological safety of ready-to-eat ham products.
基金Supported by Natural Science Foundation of Anhui Province(1508085QC64)~~
文摘[Objective] This study aimed to detect the reliability of LAMP method for detecting Listeria monocytogenes in dairy food. [Method] Based on the sequence of hlyA gene encoding listeriolysin O in Listeria monocytogenes, the LAMP method was established for detecting Listeria monocytogenes in dairy food. [Result] The es- tablished LAMP rapid detection method has .high specificity and sensitivity, which are equivalent to those of real-time fluorescent quantitative PCR. The detection re- sults of Listeria monocytogenes in dairy food by established LAMP method were completely consistent with those by bacterial isolation method. [Conclusion] The de- tection results of Listeria monocytogenes by LAMP method can be directly identified by naked eye, so the established LAMP method was suitable for the detection of Listeria monocytogenes in dairy food in emergency situations.
文摘Listeria monocytogenes is the pathogen of listeriosis and it causes severe infections like septicemia, encephalitis, and meningitis, especially in immunocompromised individuals, newborns, and pregnant women. Its wide distribution in the environment and ability to survive or even grow under adverse conditions has made L. monocytogenes an important public health concern and in food industry.
基金financially supported by the National Natural Science Foundation of China(31771951,32072199,31801510)the Beijing Natural Science Foundation(KZ201810011016).
文摘Listeria monocytogenes is a worrisome food-borne pathogen threatening global food safety.Our previous study proved that lipopeptide brevilaterin B showed efficient antibacterial activity against L.monocytogenes by interacting with the cell membrane.This research further explored the antibacterial mechanism of brevilaterin B against L.monocytogenes at the sub-minimum inhibition concentration via transcriptomic analysis.Brevilaterin B induced growth inhibition rather than direct membrane lysis in L.monocytogenes at the minimum inhibitory concentration.Transcriptomic analysis showed 1779 difference expressed genes,including 895 up-regulated and 884 down-regulated genes.Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis indicated that brevilaterin B influenced multiple pathways of L.monocytogenes,including peptidoglycan biosynthesis,membrane transport(ATP-binding cassette transports,ion transport),cellular metabolism(amino acid and lipid metabolism),ATP synthesis,and activation of the stress response(quorum sensing and bacterial chemotaxis).In conclusion,brevilaterin B affects gene expression related to biosynthesis,transport and stress response pathways on the membrane of L.monocytogenes.The present work provides the first transcriptomic assessment of the antibacterial mechanism of lipopeptide brevilaterin B at the gene level.
文摘BACKGROUNDIntracranial Listeria infections are common in newborns and immunocompromisedindividuals, but brainstem abscesses are rare.CASE SUMMARYWe report a rare case of brainstem abscesses caused by Listeria monocytogenes in apreviously healthy adult patient. The patient’s magnetic resonance imagingexamination showed multiple brain abscesses, and his second cerebrospinal fluidculture test indicated the presence of Listeria monocytogenes. Despite earlyempirical therapy, the patient’s condition progressively deteriorated. Because thepatient's abscesses were located in the brainstem and multiple lobes, surgery wasnot possible. The patient died 40 d after admission.CONCLUSIONThis case highlights the importance of rational clinical use of drugs to avoidpotentially serious infectious complications.
基金supported by grants from the National Natural Science Foundation of China (No. 30600535 and No.30901288)
文摘Listeria monocytogenes(LM),a Gram-positive facultative intracellular bacterium,can be used as an effective exogenous antigen expression vector in tumor-target therapy.But for successful clinical application,it is necessary to construct attenuated LM stain that is safe yet retains the potency of LM based on the full virulent pathogen.In this study,attenuated LM and recombinants of LM expressing melanoma inhibitory activity(MIA) were constructed successfully.The median lethal dose(LD 50) and invasion efficiency of attenuated LM strains were detected.The recombinants were utilized for immunotherapy of animal model of B16F10 melanoma.The level of MIA mRNA expression in tumor tissue was detected by using real-time polymerase chain reaction(PCR) with specific sequence,meanwhile the anti-tumor immune response was assayed by flow cytometric analysis and enzyme-linked immunosorbent spot(ELISPOT) assay.The results showed the toxicity and invasiveness of attenuated LM were decreased as compared with LM,and attenuated LM expressing MIA,especially the double-genes attenuated LM recombinant,could significantly induce anti-tumor immune response and inhibit tumor growth.This study implicates attenuated LM may be a safer and more effective vector for immunotherapy of melanoma.
文摘Much progress of application of bacterial vaccine in treatment and prevention of tumor was acquired,which showed broad prospect in clinical study of animals and humans. Listeria monocytogenes( L. monocytogenes) was considered much important by virtue of its special characteristic of biology and immunology.L. monocytogenes was ingested by professional or part-time phagocytes,survived and proliferated in the phagocytes under synergism of toxic factor secreted by itself,meanwhile,the cellular and humoral immune response was induced. Antigenic gene of specific tumor was loaded in the attenuated L. monocytogenes,which can enhance immune response of host cells. Effective cell targeted to enter tumor tissue and acted on tumor cells to induce apoptosis of tumor cells. Tumor degenerated not easy to reappear. Therefore,recombinant attenuated L. monocytogenes was a safe and effective anti-cancer vaccine vector. Now the work of researchers mainly focuses on solving practical problem in clinical application. Biological characteristics of L. monocytogenes,feasibility and superiority of L. monocytogenes as targeted vaccine vector,problem and prospect of L. monocytogenes in clinical application of anti-tumor were reviewed in this paper.
文摘A bacteriocin producing strain of Lactococcus lactis subsp. lactis LABW4 was isolated from naturally fermented milk product which exhibited strong antibacterial activity against Listeria monocytogenes MTCC657, a food spoilage psychrophilic organism. Both cell free and heat killed supernatants of LABW4 were effective to produce zones of inhibition against L. monocytogenes in vitro. The antibacterial metabolite(s) of LABW4 showed strong cidal effect on the growth of L. monocytogenes. Meat samples, mixed with heat killed supernatant of LABW4 when inoculated with Listeria, remain fresh up to 25 days in refrigerated condition whereas spoilage started immediately after 24 hours of inoculation for control sets. Enhancement of Lactate dehydrogenase of L. monocytogenes upon treatment with LABW4 cell free supernatant suggested its lytic mode of action. Cell lysis or degradations were also supported by scanning electron micrograph of treated cells.
文摘Floor drains in processing environments harbor Listeria spp. due to continuous presence of humidity and organic substrates. Cleaning and washing activities in food-processing facilities can translocate the bacterial cells from the drain to the surrounding environment, thus contaminating food products still in production. This study evaluated the potential for translocation of Listeria monocytogenes from drains to food contact surfaces in the surrounding environment using Listeria innocua as a surrogate. A 7 × 7 × 8-foot polycarbonate flexi-glass chamber with a 10-inch-diameter drain mounted on an aluminum cabinet was used. Stainless steel coupons (6.4 × 1.9 × 0.1 cm, 12 per height) were hung at 1, 3, and 5 feet inside the chamber. Four treatment sets;non-inoculated, non-treated;non-inoculated, treated;inoculated, treated;inoculated non-treated;and two subtreatments of 8 h and 48 h were performed. For the inoculated sets, meat slurry (10 gof ground beef in 900 mL water) and a four-strain cocktail of Listeria innocua at 7 - 8 log CFU/mL were used. For the treated sets, in addition, a commercial cleaner and sanitizer was applied. The drain was cleaned using a pressure hose (40 - 50 psi) after 8 h and 48 h. Coupons were then removed and enriched in listeria enrichment broth to establish if any cell translocated from the drain onto the stainless steel coupons via aerosols generated during washing. Confirmation was done using VIP Listeria rapid test kits. Results indicated translocation at all three heights ranging from 2% - 25%. Significantly higher translocation (p Listeria spp. from drains to food contact surfaces does occur and increases with increased proximity to the drain.
文摘Rapid identification and characterization of Listeria monocytogenes are required for the food industry, epidemiological studies, and disease prevention and control. However, typing procedures are labor-intensive and time-consuming, and they require technical expertise, a panel of sera and reference culture strains or sophisticated and expensive equipment. To improve upon traditional diagnostic methods for L. monocytogenes we developed and evaluated an efficient procedure for the specific identification of L. monocytogenes and the major pathogenic serotypes of the species based on loop-mediated isothermal amplification (LAMP). Four individual reactions were designed using primers targeting any L. monocytogenes serotypes (LAMP-AS) and the 1/2a (LAMP-1/2a), 1/2b (LAMP-1/2b), and 4b (LAMP-4b) serotypes. The procedure distinguished L. monocytogenes from closely genetically related species and the targeted serotypes. Cross-reactivity with a few rare serotypes isolated from food or clinical samples did not impair the usefulness of the procedure. Thus, our approach constitutes a fast, easy and low-cost alternative for L. monocytogenes diagnosis and serotyping and may be useful for surveillance and epidemiological investigation programs.
基金funded by the Foundation for Re-search Levy on Agricultural Products,by the Norwegian Research Council,and by the Food Quality and safety,ProSafeBeef Food-CT-2006-36241 research program(part of the EU 6th Framework Program)Dr.Michél He-braud,INRA,France,is appreciated for providing L.monocytogenes isolates to the study.
文摘Contamination of food with spoilage bacteria and pathogens from food processing environment remains a challenge for the food industry. Bacteria able to persist in such environments over time must survive several hygienic hurdles. The aim of this study was to identify bacteria surviving practical disinfection and compare their survival abilities with representative isolates of the pathogen Listeria monocytogenes. Bacteria isolated from processing surfaces after cleaning and disinfection in a meat abattoir were identified. Selected isolates of the most frequently isolated bacterial genera along with eight meat associated L. monocytogenes were further characterized with regard to biofilm formation abilities at 12℃ and 20℃, tolerance to desiccation (stainless steel at 70% RH at 12℃) and bactericidal effects of recommended in-use-concentrations of four commercial disinfectants on stainless steel surface. The most dominating bacterial genera based on counts on non-selective agar were Aerococcus, Acinetobacter, Pseudomonas, Serratia and Staphylococcus. Isolates of Citrobacter. Enterobacter and Serratia dominated on agar plates selective for Enterobacteriaceae. In general, Gram negative bacteria formed more biofilm than Gram positives, especially at 12℃ with the best biofilm formers being Acinetobacter, Citrobacter and Pseudomonas. Listeria monocytogenes were poor biofilm formers. Gram positives survived better air drying than Gram negatives. Strains of L. monocytogenes were more sensitive to desiccation than the other Gram positives;Aerococcus, Kocuria and Staphylococcus. Two disinfectants containing peracetic acid and a disinfectant containing alkylaminoacetate had limited or no antibacterial effect against bacteria dried on stainless steel. A quaternary ammonium compound-based disinfectant provided >2 log reductions of Aerococcus, Acinetobacter and Listeria. Only 0.5 log reductions were obtained against Staphylococcus and no bactericidal effect against Serratia. In this study the dominating flora in a meat abattoir was isolated and identified. Several of these bacteria were better biofilm formers and more resistant to desiccation and disinfection than L. monocytogenes. The disinfectants tested had limited bactericidal activity against surface associated bacteria.
