Monocytogenes 4b Research Articles

Determination of the Antimicrobial Activity of Four Different Tea Extracts Against Foodborne Pathogens

Objectives: Due to the presence of various bioactive compounds including polyphenols and saponins, tea exhibits antimicrobial activity against microorganisms. The aim of this study is to investigate the antimicrobial activity of black, white, green, and oolong tea against some foodborne pathogens. Materials and Methods: For the extraction of tea samples, the Soxhlet method was chosen, and MIC values were determined using the broth micro-dilution method for the evaluation of antimicrobial activity. The selection of tea varieties used in the study was determined based on their consumption frequencies and popularity. Escherichia coli ATCC 25922, Proteus vulgaris ATCC 7829, Staphylococcus aureus ATCC 292123, and 3 Listeria monocytogenes (L. monocytogenes ATCC 19111, L. monocytogenes ATCC 7644, and L. monocytogenes 4b ATCC 19115) strains were used as indicator microorganisms in the study. Results: The highest antimicrobial activity was observed against L. monocytogenes strains in white tea, with an MIC value of 0.256 mg/mL. The comparison of antimicrobial activity of different tea types revealed that black tea exhibited lower antimicrobial activity compared to other tea varieties. Conclusion: The findings of the current study indicate that non-fermented tea types, such as white and green tea, which are known to be more effective in terms of healthy nutrition, exhibit higher antimicrobial activity. Therefore, it is believed that non-fermented tea varieties would be more effective in combating pathogenic microorganisms.

Biofilm Quantification in Listeria monocytogenes 4B Serotype isolated from Animals of Gujarat State, India

Biofilm Quantification in Listeria monocytogenes 4B Serotype isolated from Animals of Gujarat State, India

Foodborne Zoonoses Common in Hunted Wild Boars

The northern European wild boar population has increased during the last decade. Highest wild boar numbers in Finland have been reported in the southeastern part near the Russian border. Wild boars may be infected with several human and animal pathogens. In this study, we investigated the presence of important foodborne pathogens in wild boars hunted in 2016 in Finland using serology, PCR and culturing. Seroprevalence of Salmonella (38%) and Yersinia (56%) infections was high in wild boars. Antibodies to hepatitis E virus, Toxoplasma gondii and Brucella were found in 18%, 9% and 9% of the wild boars, respectively. Trichinella antibodies were detected in 1% of the animals. We recorded no differences in the seroprevalence between males and females. However, Yersinia and T. gondii antibodies were detected significantly more often in adults than in young individuals. Listeria monocytogenes (48%) and stx-positive Escherichia coli (33%) determinants were frequently detected in the visceral organs (spleen and kidneys) by PCR. Yersinia pseudotuberculosis O:1 and L. monocytogenes 2a and 4b were identified by culturing from the PCR-positive samples. Brucella suis biovar 2 was isolated from visceral organs. No African swine fever, classical swine fever or Aujeszky’s disease were detected in the wild boars. Our study shows that wild boars are important reservoirs of foodborne pathogens.

Meningoencephalitis case with listeriosis etiology in an immunocompetent female patient

Nervous forms of listeriosis are observed in 5%10% of persons suffering from this disease and in 75% of children with bacteriologically confirmed listeriosis as well. The most widespread clinical variant is Listeria meningitis, making up 15% of all cases of bacterial and serous meningitides. The mortality rate at neurolisteriosis reaches 30%40%. A case of acute meningoencephalitis associated with Listeria monocytogenes 4b in a 37-year-old immunocompetent woman is described. The disease was characterized by subacute onset, manifested intoxication, long-lasting and high-grade fever, cerebral coma, bulbar syndrome, right-side hemiparesis, bilateral hypertonus of the wrist flexors, strabism, anisocoria, manifested leukocytosis with leukocyte formula stab shift, ESR 4559 mm/hour. Cerebrospinal fluid test: cytosis 663 сells in 1 mcl, neutrophils 79%, lymphocytes 21%, protein 1451 mg/l, glucose 3.8 mmol/l. Diagnosis had been confirmed with detection of IgM against Listeria monocytogenes 4b in liquor using the indirect immunofluorescence reaction and Listeria monocytogenes by means of PCR. Antibacterial therapy had been conducted using Meropenem, Ampicillinum, endolumbal administration of 4 mg once daily of Gentamycinum combined with intravenous administration of 24 million of units/day of Penicillin. On day 50, she was transferred for rehabilitation treatment to the Department of Neurology.

Potansiyel Antimikrobiyal Ajanlar Olarak Yeni Asimetrik Schiff Bazlarının Sentezi

Novel unsymmetrical Schiff bases (L3a-L3c) were synthesized by using a two-stage method. The starting Schiff bases were prepared by the reaction of 2-aminophenol (or 2-amino-4-methylphenol or 2-amino-4-chlorophenol) with 1-nitro-2-naphthaldehyde. In these compounds, the nitro groups were reduced to amino groups using selective reducing agent and then 2-hydroxybenzaldehyde were added. Thus, three new unsymmetric Schiff base ligands were obtained. The antimicrobial activity of the synthesized unsymmetric Schiff bases were evaluated against some pathogenic strains (Shigella dysenteria type 7, Listeria monocytogenes 4b, Escherichia coli, Salmonella typhi H, Staphylococcus epidermis, Brucella abortus, Micrococcus luteus, Bacillus cereus sp., Pseudomonas putida sp.) and yeast (Candida albicans).

Adhesion of Campylobacter jejuni Is Increased in Association with Foodborne Bacteria.

The aim of this study was to evaluate Campylobacter jejuni NTCT 11168 adhesion to abiotic and biotic surfaces when grown in co-culture with Escherichia coli ATCC 11229 and/or Listeria monocytogenes 4b. Adhesion of C. jejuni to polystyrene and to Caco-2 cells and Acanthamoeba castellanii was lower for at least 3 log CFU/mL compared to E. coli and L. monocytogenes. Electron micrographs of ultrathin sections revealed interactions of C. jejuni with host cells. In co-culture with E. coli and L. monocytogenes, adhesion of C. jejuni to all tested surfaces was significantly increased for more than 1 log CFU/mL. There was 10% higher aggregation for C. jejuni than for other pathogens, and high co-aggregation of co-cultures of C. jejuni with E. coli and L. monocytogenes. These data show that C. jejuni in co-cultures with E. coli and L. monocytogenes present significantly higher risk than C. jejuni as mono-cultures, which need to be taken into account in risk evaluation. C. jejuni adhesion is a prerequisite for their colonization, biofilm formation, and further contamination of the environment. C. jejuni survival under adverse conditions as a factor in their pathogenicity and depends on their adhesion to different surfaces, not only as individual strains, but also in co-cultures with other bacteria like E. coli and L. monocytogenes.

The probiotic, Leuconostoc mesenteroides, inhibits Listeria monocytogenes biofilm formation

AbstractListeria monocytogenes biofilm formation renders these cells highly resistant to current sanitation methods, and probiotics may be a promising approach to the efficient inhibition of Listeria biofilms. In the present study, three Leuconostoc mesenteroides strains of lactic acid bacteria isolated from kimchi were shown to be effective probiotics for inhibiting Listeria biofilm formation. Biofilms of two L. monocytogenes serotypes, 1/2a (ATCC15313) and 4b (ATCC19115), in dual‐species culture with each probiotic strain were decreased by more than 40‐fold as compared with single‐species Listeria biofilms; for instance, a reduction from 5.4 × 106 colony forming units (CFU)/cm2 L. monocytogenes ATCC19115 in single‐species biofilms to 1.1 × 105 CFU/cm2 in dual‐species biofilms. Most likely, one of the Leuconostoc strains, L. mesenteroides W51, led to the highest Listeria biofilm inhibition without affecting the growth of L. monocytogenes. The cell‐free supernatant from the L. mesenteroides W51 culture containing large protein molecules (>30 kDa) also inhibited Listeria biofilms. These data indicate that Leuconostoc probiotics can be used to repress L. monocytogenes biofilm contamination on surfaces at food processing facilities.

Investigation of photophysical behaviours and antimicrobial activity of novel benzo-15-crown-5 substituted coumarin and chromone derivatives

Two different series of crown ether compounds (4-11) were synthesized by the reactions of 4′,5′-bis(bromomethyl)benzo-15-crown-5 (3) and 4′-amino-benzo-15-crown-5 with hydroxycoumarin and chromone derivatives. Coumarin-crown ether compounds (4 and 5) were synthesized by the reactions of 4′,5′-bis(bromomethyl)benzo-15-crown-5 (3) with 4-hydroxycoumarin and 7-hydroxycoumarin. Chromone-crown ether compounds (6-11), were synthesized by the condensation reactions of 4′-amino-benzo-15-crown-5 with 3-formylchromone and 6-methyl-3-formylchromone in different solvent media. Sodium and potassium complexes (4a-11a, 4b-11b) of new coumarin and chromone substituted benzo-15-crown-5 (B15C5) ligands (4-11) were prepared with NaSCN and KSCN, respectively. The syntheses of the novel crown ether compounds (4-11) and complexes (4a-11a, 4b-11b) were elucidated by the elemental analysis, FTIR, 1H NMR, 13C NMR and MS spectral data. The metal selectivities and effects of metal cations (Li+, Na+, K+, Mg2+, Ca2+, Ba2+, Ag+, Al3+, Cu2+, Zn2+, Ni2+, Pb2+, Fe3+, Cr3+) to the new crown ether compounds (4-11) were investigated by the absorption and fluorescence spectra. In addition, all of these substances were examined for antibacterial activity against pathogenic strains Listeria monocytogenes 4b, Staphylococcus aureus, Escherichia coli, Salmonella typhi H, Bacillus cereus, Micrococcus luteus, Shigella dysenteria type 2, Staphylococcus epidermidis, Proteus vulgaris, Klebsiella pneumonia sp., Serratia marcescens sp. and antifungal activity against Candida albicans.

Characterization of Listeria Monocytogenes Originating from the Spanish Meat-Processing Chain.

Using agglutination techniques, 118 Listeria monocytogenes isolates from red meat and poultry were serotyped. Strains were ascribed to the serotypes 4b/4e (44.1% of the strains), 1/2 (a, b or c; 28.0%), 4c (6.8%), 4d/4e (5.9%) and 3 (a, b or c; 2.5%). Among these are the serotypes most frequently involved in cases of human listeriosis. The susceptibility of 72 strains to 26 antibiotics of clinical importance was determined by disc diffusion (Clinical and Laboratory Standards Institute; CLSI). High levels of resistance were observed to cefoxitin (77.8% of the strains showed resistance), cefotaxime (62.5%), cefepime (73.6%), nalidixic acid (97.2%), nitrofurantoin (51.4%) and oxacillin (93.1%). Less than 3% of the strains showed resistance to the antibiotic classes used in human listeriosis therapy (i.e., ampicillin, gentamicin, rifampicin, chloramphenicol, enrofloxacin, vancomycin, trimethoprim-sulfamethoxazole, erythromycin, and tetracycline). The influence of species and serotype on the growth kinetics (modified Gompertz equation) and on the adhesion ability (crystal violet staining) of nine isolates of L. monocytogenes (serotypes 1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a, 4b, and 4d), and one strain of Listeria ivanovii were investigated. The maximum growth rate (ΔOD420-580/h) varied between 0.073 ± 0.018 (L. monocytogenes 1/2a) and 0.396 ± 0.026 (L. monocytogenes 4b). The isolates of L. monocytogenes belonging to serotypes 3a and 4a, as well as L. ivanovii, showed a greater (p < 0.05) biofilm-forming ability than did the remaining strains, including those that belong to the serotypes commonly implied in human listeriosis (1/2a, 1/2b, 1/2c and 4b). The need for training in good hygiene practices during the handling of meat and poultry is highlighted to reduce the risk of human listeriosis.

Comparative whole genome analysis of Listeria monocytogenes 4b strains reveals least genome diversification irrespective of their niche specificity

Listeria monocytogenes has emerged as the deadly pathogen inflicting high mortality in humans and animals. To investigate the strain-specific characteristics of L. monocytogenes, and their role(s) in virulence and ecological sustenance, we sequenced genome of three L. monocytogenes strains BHU1, 2 and 3 isolated from the Ganges river, agricultural soil and human placenta bit, respectively, and compared it with L. monocytogenes EGD-e serovar 1/2a and L. monocytogenes F2365 serovar 4b strain. The contigs of all the three strains had a similarity (>90%) in regions that aligned with EGD-e and F2365. A total of 2872 core genes on the set of strains were identified in BHU1, 2 and 3 strains. In the mice virulence assay, BHU2 and 3 strains showed pathogenicity while BHU1 was non-pathogenic. These strains were also characterized with unique genes (8 genes in BHU1, 12 in BHU 2, and 17 in BHU 3 strain). Phylogenetic analysis based on multilocus sequence typing revealed BHU1, 2 and 3 strains to be more closely related to lineage I, serotype 4b, clonal complex 1, and sequence type 328. BHU1 strain seemed to harbor nucleotide mutation from A to G in the major virulence genes i.e. hemolysin D and listeriolysin O. Strain-specific mutations 8, 5 and 2 were identified in BHU1, 2 and 3, respectively, compared to F2365. Though all the three strains were genetically very close, the observed differences may play the crucial role(s) in their virulence attributes, and also, in the prevalence of L. monocytogenes.

Isolation, characterization and evaluation of virulent bacteriophages against Listeria monocytogenes

Bacteriophages are considered a potential antimicrobial food intervention due to their ability to inactivate target bacteria in different environments. This study was undertaken to isolate, characterize, and identify a mixture of phages that could be used for control of Listeria monocytogenes. A total of 37 phages were isolated from raw sewage sludge using L. monocytogenes serotypes 4b, 1/2a and 1/2b strains. The host range of these phages was determined by spot-testing. Ten lytic phages were selected for further evaluation with efficiency of plating (EOP) analysis and characterization by pulsed field gel electrophoresis (PFGE). According to the spot tests and EOP results, the isolated phages against L. monocytogenes 4b strains were found to be capable of lysing a wider range of ribotypes. Also, three phages specific for 1/2a and 1/2b serotypes had similar lysis capabilities over a range of target Listeria with high EOP values between 0.5 and 1.0. PFGE analysis identified 5 distinct restriction profiles of the 10 selected phages whose DNA was digested with either EcoRI or HinDIII. Transmission electron microscopy (TEM) pictures revealed that five selected phages belonged to the Myoviridae and one phage to the Podoviridae family. Based on screening results, a phage cocktail (LP1) comprised of six lytic phages was used to inactivate a mixed culture of five L. monocytogenes strains. LP1 was able to lyse bacterial cells within 30–60 min at multiplicity of infection values (MOI, PFU/CFU) of 1000 and maintained the target cells under detection levels for 24 to 48 h at 4, 10, and 30 °C. These results suggested the LP1 phage collection contained effective and strongly lytic phages that may serve as antibacterial preparation to control L. monocytogenes of different serotypes.

Complete Genome Sequences of Two Listeria monocytogenes Serovars, 1/2a and 4b, Isolated from Dairy Products in Brazil.

Listeria monocytogenes is the foodborne pathogen responsible for a bacterial infection called listeriosis. Here, we present the whole-genome sequences of two L. monocytogenes serovars, 1/2a and 4b, which are considered the most prevalent in food processing plants and listeriosis outbreaks, respectively.

The stimulating effect of exometabolites of the marine microalgae Phaeodactylum tricornutum Bohlin on reproduction of Listeria monocytogenes

The biological activity of ethyl acetate extract of exometabolites from the marine microalgae Phaeodactylum tricornutum against a test culture of Listeria monocytogenes 4b has been investigated. It was shown that the stimulating effect of algal exometabolites on the growth of pathogenic bacteria increased maximally by 98.3% on day 6 of the cultivation, if the active substances comprising the culture liquid of P. tricornutum were separated by successive extractions with solvents in order of increasing polarity (hexane, benzene, ethyl acetate), and by 150% on day 3, if the substances from the ethyl acetate extract of exometabolites were separated by column chromatography. It is noted that the fraction of biologically active substances maximally stimulating the growth of L. monocytogenes can be used to prepare an accumulation medium for detecting these patho- genic bacteria in marine environments and hydrobionts.

Effect of chitosan on spoilage bacteria, Escherichia coli and Listeria monocytogenes in cured chicken meat

The effects of essential oil (EO) of oregano and chitosan on the microbial quality and growth inhibition of Listeria monocytogenes and Escherichia coli O157:H7 in the Iranian traditional ready-to-barbecue chicken was evaluated. Thus, three groups of samples were prepared. One of them was considered to evaluate for aerobic plate count (APC), lactic acid bacteria (LAB), psychrophilic and enterobacteriacae counts and the other two groups were inoculated with E. coli O157:H7 and L. monocytogenes 4b to investigate the effect of oregano EO and chitosan on pathogenic bacteria. All groups were stored at 3, 8 and 20°C. Oregano showed antibacterial effects against APC, LAB, psychrophilics, enterobacteriacae and E. coli O157:H7, whereas, such an effect was not observed against L. monocytogenes. Chitosan individually did not show an inhibitory effect on the spoilage-inducing bacteria and E. coli, but was effective against L. monocytogenes. Using chitosan and oregano EO in combination can reduce the number of spoilage and safety indicators and also the two food-borne pathogens in ready-to-barbecue chicken meat.

Impact of Sod on the expression of stress-related genes in Listeria monocytogenes 4b G with/without paraquat treatment.

Listeria monocytogenes is a foodborne pathogen that causes listeriosis. Paraquat can generate reactive oxygen species (ROS) in cells, which results in oxidative stress. It was first shown that 1 mM of paraquat inhibited the growth rate of a superoxide dismutase (sod)-deletion mutant (∆sod) generated from L. monocytogenes 4b G but not in the wild-type, and induced the expression of other resistance genes (kat, fri, perR, sigB, and recA) as well as sod in the wild type. Interestingly, without paraquat treatment the expression of all the 5 genes were repressed in ∆sod compared to the wild type, while the expression of recA triggering SOS response, a global response to DNA damage, was increased in ∆sod in the presence of 1 mM paraquat. Taken together, these results suggest that SOD plays a central role in oxidant defense of L. monocytogenes 4b G, and SOS probably significantly impacts ∆sod survival under oxidative stress.

Multi-Virulence-Locus Sequence Typing of 4bListeria monocytogenesIsolates Obtained from Different Sources in India over a 10-Year Period

Listeria monocytogenes is an emerging foodborne pathogen responsible for listeriosis. The incidence of listeriosis has increased during the last 2 decades due to the increase in consumption of ready-to-eat foods and change in food consumption habits. Outbreaks and sporadic cases of listeriosis have been reported in developed countries. These reports have helped determine the safety practices needed to control listeriosis. Although L. monocytogenes has been reported from humans, animals, and a variety of foods in India, limited data exist with respect to prevalence and distribution of L. monocytogenes in the Indian subcontinent. The Indian Listeria Culture Collection Centre in Goa maintains all of the isolates received for subtyping and molecular characterization. Of the listerial isolate collection maintained by this center, three fourths of the isolates are of 4b serotype, while the number of other serotypes is very low. Therefore, we screened L. monocytogenes serotype 4b isolates to determine their relevance to previously defined epidemics and/or outbreaks using multi-virulence-locus sequence typing (MVLST). A total of 25 isolates in serogroup 4b of L. monocytogenes were randomly selected from a repository of 156 L. monocytogenes 4b isolates obtained from different sources in India over a period of 10 years. MVLST sequence types (virulence types, VTs) were compared to known epidemic clones and other known isolates in the L. monocytogenes MVLST database. The 25 isolates were grouped into three clusters. Cluster I comprised 21 isolates including animal (n=9), human (n=4), and food (n=8), which matched Epidemic Clone I (ECI, VT20). Three isolates-two from animal and one from food-formed a cluster while a single animal isolate was placed into two novel VTs (VT98 and VT99), respectively. Based on these findings, it can be inferred that ECI has been isolated from a variety of sources and places and has persisted in India for at least 10 years.

Synthesis, Characterization, and Antimicrobial Activities of New N-(2-hydroxy-1-naphthalidene)-amino Acid (L-Tyrosine, L-Arginine, and L-Lysine) Schiff Bases and Their Manganese(III) Complexes

A new series of manganese(III) complexes Na[Mn(L1)2].3H2O, Na3[MnL2(CH3COO)4].2H2O, Na[Mn(L3)2].2H2O and amino acid Schiff bases (H2L1); [N-(2-hydroxy-1-naphthylidene)tyrosine], (H2L2); [N-(2-hydroxy-1-naphthylidene)arginine], (H2L3); [N-(2-hydroxy-1-naphthylidene)lysine] have been prepared from 2-hydroxy-1-naphthaldehyde and a-amino acids (L-tyrosine, L-arginine, and L-lysine). The structures of the compounds were identified using elemental analyses, IR, UV-VIS, 1H-NMR spectra, magnetic susceptibility measurements, and thermogravimetric analyses (TGA). All of these substances have been also examined for antibacterial activity against the pathogenic strains S. aureus, Sh. dys. typ 7, L. monocytogenes 4b, E. coli, S. typhi H, S. epidermis, Br. abortus, M. luteus, B. cereus, P. putida, and antifungal activity against C. albicans.

Biochemical and molecular characteristics of Listeria monocytogenes isolates from a prosthetic mitral heart valve-bearing patient´s blood cultures

Background: In Brazil, listeriosis is not a notifiable disease; thus, the incidence of Brazilian cases remains unknown. Listeria monocytogenes is not always included in automated systems, and its detection depends on the high skill level of microbiology laboratory professionals. This paper describes the characteristics of L. monocytogenes isolates fortuitously obtained from an endocarditis case in Recife, PE, Brazil. Methods: Six bacterial isolates obtained from six blood cultures from a 28-year-old male bearing a prosthetic mitral heart valve were analyzed by PCR using primers specific of L. monocytogenes to confirm a presumptive identification, determine the serotype and presence of the virulence genes (inlA, inlB, inlC, inlJ, hly, plcA, actA, prfA) in an attempt to determine the Listeria genotype by PCR-ribotyping. Results: The samples were identified as L. monocytogenes 4b. All investigated virulence genes were amplified by PCR, and the identity of the amplified segments was confirmed by sequencing. A deletion of 105 base pairs was detected in the actA gene. All of the samples generated the same PCR-ribotype pattern, clustered into a single ribotype, and were considered a single strain. Conclusion: L. monocytogenes infection should be considered in endocarditis differential diagnoses, especially among high-risk groups, due to its high pathogenicity and the environmental ubiquity.

A Mariner Transposon-Based Signature-Tagged Mutagenesis System for the Analysis of Oral Infection by Listeria monocytogenes

Listeria monocytogenes is a Gram-positive foodborne pathogen and the causative agent of listerosis a disease that manifests predominately as meningitis in the non-pregnant individual or infection of the fetus and spontaneous abortion in pregnant women. Common-source outbreaks of foodborne listeriosis are associated with significant morbidity and mortality. However, relatively little is known concerning the mechanisms that govern infection via the oral route. In order to aid functional genetic analysis of the gastrointestinal phase of infection we designed a novel signature-tagged mutagenesis (STM) system based upon the invasive L. monocytogenes 4b serotype H7858 strain. To overcome the limitations of gastrointestinal infection by L. monocytogenes in the mouse model we created a H7858 strain that is genetically optimised for oral infection in mice. Furthermore our STM system was based upon a mariner transposon to favour numerous and random transposition events throughout the L. monocytogenes genome. Use of the STM bank to investigate oral infection by L. monocytogenes identified 21 insertion mutants that demonstrated significantly reduced potential for infection in our model. The sites of transposon insertion included lmOh7858_0671 (encoding an internalin homologous to Lmo0610), lmOh7858_0898 (encoding a putative surface-expressed LPXTG protein homologous to Lmo0842), lmOh7858_2579 (encoding the HupDGC hemin transport system) and lmOh7858_0399 (encoding a putative fructose specific phosphotransferase system). We propose that this represents an optimised STM system for functional genetic analysis of foodborne/oral infection by L. monocytogenes.

Schiff bases attached L-glutamine and L-asparagine: First investigation on antimutagenic and antimicrobial analyses

This study was conducted to evaluate the antimutagenic and antimicrobial activities of Schiff bases attached L-glutamine and L-asparagine. Antibacterial activities of the compounds against S. aureus, Sh. dys. typ 7, L. monocytogenes 4b, E. coli, S. typhi H, S. epidermis, Br. abortus, M. luteus, B. cereus, P. putida, and antifungal activity against Candida albicans were studied. These compounds were investigated for antimutagenic properties against Aflatoxin Bı (AFBı) using micronuclei (MN) assay in human lymphocyte cell culture in vitro. The protective role of these compounds against AFBı-induced MN is probably related to its doses.