Listeria Monocytogenes 4b Research Articles

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

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.

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.

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.

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.

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.

Mutations in gltB and gltC reduce oxidative stress tolerance and biofilm formation in Listeria monocytogenes 4b G

The foodborne pathogen Listeria monocytogenes has the capability to persist on surfaces in food-processing environments, and the organism is resistant to environmental stresses. In this study, a Tn917 insertion mutant of L. monocytogenes 4b G showing reduced biofilm formation and sensitivity to oxidative stress was identified and characterized. The transposon insertion site within the gltB gene was identified by inverse PCR. The gltC gene is located upstream and is reported to be transcribed divergently from gltB. Mutants with deletions in gltB and gltC were constructed and both showed reduced biofilm formation and increased sensitivity to H2O2 compared to the wild-type. In the wild-type strain, gltB and gltC expressions were induced approximately 8-fold and 14-fold by quantitative RT-PCR, respectively, with exposure to H2O2, providing further evidence that their gene products may be involved in the response to oxidative stress. In addition, after the induction by H2O2 and compared with the wild-type, the gltB expression in ΔgltC and the gltC expression in ΔgltB were down-regulated about 4-fold (p<0.05) and 3-fold (p<0.05) respectively. These data demonstrate a possible mutual regulation between gltB and gltC expressions under oxidative stress conditions, partly explaining the similar oxidative stress responses of ΔgltB and ΔgltC. Furthermore, ΔgltB and ΔgltC exhibited decreased adherence to a glass surface compared to the wild-type, while the cell motility of wild-type and mutant strains was similar. It is hypothesized that some cell surface characteristics unrelated with cell motility may be introduced into the mutants by the inactivation of gltB or gltC, which might lead to the reduction in biofilm formation. We conclude that both gltB and gltC are involved in the biofilm formation as well as the oxidative stress tolerance in L. monocytogenes 4b G, by pathways that remain yet unclear.

The expression of superoxide dismutase (SOD) and a putative ABC transporter permease is inversely correlated during biofilm formation in Listeria monocytogenes 4b G.

Little is known about the molecular basis of biofilm formation in Listeria monocytogenes. The superoxide dismutase (SOD) of the deletion mutant of lm.G_1771 gene, which encodes for a putative ABC transporter permease, is highly expressed in biofilm. In this study, the sod gene deletion mutant Δsod, and double deletion mutant of the sod and lm. G_1771 genes Δ1771Δsod were used to investigate the role of SOD and its relationship to the expression of the putative ABC transporter permease in biofilm formation. Our results showed that the ability to form a biofilm was significantly reduced in the Δsod mutant and the Δ1771Δsod double mutant. Both Δsod and Δ1771Δsod mutants exhibited slow growth phenotypes and produced more reactive oxygen species (ROS). The growth was inhibited in the mutants by methyl viologen (MV, internal oxygen radical generator) treatment. In addition, the expression of one oxidation resistance gene (kat), two stress regulators encoding genes (perR and sigB), and one DNA repair gene (recA) were analyzed in both the wild-type L. monocytogenes 4b G and the deletion mutants by RT-qPCR. The expression levels of the four genes were increased in the deletion mutants when biofilms were formed. Taken together, our data indicated that SOD played an important role in biofilm formation through coping with the oxidant burden in deficient antioxidant defenses.

Polystyrene Containing Carbinolamine/Azomethine Potentially Useful as Antimicrobial Agent: Synthesis and Biological Evaluation

An investigation of antimicrobial properties of 12 novel modified polymer derived from the condensation reaction of (aminomethyl)polystyrene and four substitute salicylaldehyde (2-hydroxy benzaldehyde, 5-fluoro-2 hydroxy benzaldehyde, 5-fluoro-3-chloro-salicylaldehyde and 5-fluoro-3-methyl-salicylaldehyde) has been carried out and Cr(III) and Ni(II) complexes have been prepared. Modified polymers were characterized by magnetic susceptibility, elemental analyses, and spectral studies. The 1H NMR and 13C NMR spectra analysis of the polymeric carbinolamine/azomethine were determined. In addition, surface morphology and composition were determined by SEM/EDX. Thermo gravimetric analyses of polymers were carried out in nitrogen atmosphere. Antibacterial activities of the polymers attached carbinolamine/azomethine and their complexes were studied by the well-diffusion method against Listeria monocytogenes 4b, Staphylococcus aureus, Escherichia coli, Salmonella typhi H, Brucella abortus, Staphylococcus epidermis sp., Micrococcus luteus, Shigella dysenteria type 10, Bacillus cereus, Pseudomonas putida and antifungal activity against Candida albicans.

Novel polymer anchored Cr(III) Schiff base complexes: Synthesis, characterization and antimicrobial properties

New polymer-bound Schiff bases and Cr(III) complexes have been synthesized by the reaction of 4-benzyloxybenzaldehyde, polymer-bound with 2-aminophenol, 2-amino-4-chlorophenol and 2-amino-4-methylphenol. The structure of polymeric-Schiff bases and their Cr(III) complexes have been characterized by elemental analyses, magnetic measurements, IR, UV–Vis, TG-DTA and 1H-NMR. All these compounds have also been investigated for antibacterial activity by the well-diffusion method against Staphylococcus aureus (RSKK-07035), Shigella dysenteria type 10 (RSKK 1036), Listeria monocytogenes 4b(ATCC 19115, Escherichia coli (ATCC 1230), Salmonella typhi H (NCTC 901.8394), Staphylococcus epidermis (ATCC 12228), Brucella abortus (RSKK-03026), Micrococcs luteus (ATCC 93419, Bacillus cereus sp., Pseudomonas putida sp. and for antifungal activity against Candida albicans (Y-1200-NIH).

Spectroscopic characterization of novel d-amino acid-Schiff bases and their Cr(III) and Ni(II) complexes as antimicrobial agents

The aim of this work was to investigate the antibacterial and antifungal activities of novel d-amino acid-Schiff bases including fluorine atom and their Cr(III) and Ni(II) complexes. All these substances have been examined for antibacterial activity against pathogenic strains Listeria monocytogenes 4b ATCC19115, Staphylococcus aureus ATCC25923, Escherichia coli ATCC1280, Salmonella typhi H NCTC 901.8394, Brucella abortus (A.99, UK-1995) RSKK03026, Staphylococcus epidermis sp., Micrococus luteus ATCC9341, and Shigella dysenteria typ 10 NCTC 9351, and antifungal activity against Candida albicans Y-1200-NIH, Tokyo. The antimicrobial test results of these amino acid-Schiff base complexes exhibited better activity than some known antibiotics. In particular, diamagnetic Ni(II) complexes were more potent bactericides than all of the substances synthesized.

The origin of Listeria monocytogenes 4b isolates is signified by subproteomic profiling

Among the 13 known serovars of Listeria monocytogenes, strains exhibiting the serovar 4b are the most prevalently involved in epidemics of human listeriosis. The molecular reasons for the major involvement of serovar 4b strains in all major foodborne outbreaks in contrast to the lower prevalence of this serovar among food isolates remain indefinite. In order to provide further insight in the protein expression of L. monocytogenes 4b strains, the cytoplasmic and extracellular proteomes of L. monocytogenes 4b strains from different origins, i.e. environmental, clinical and asymptomatical carriage, were investigated by two-dimensional gel electrophoresis. Statistical hierarchical clustering analysis on subproteomic profiles clearly discriminated the strains according to their origin. Protein spots differentiating the subproteome patterns were identified using MALDI-TOF MS through their peptide mass fingerprint.

Synthesis and biological activity of new cycloalkylthiophene-Schiff bases and their Cr(III) and Zn(II) complexes

A series of some novel Ethyl 2-((1-hydroxynaphthalen-2-yl)methyleneamino)-5,6-dihydro-4H-cyclopenta[b]thiopehene-3-carboxylate, Ethyl 2-((1-hydroxynaphthalen-2-yl)methyleneamino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate, Ethyl 2-((1-hydroxynaphtalen-2-yl)methyleneamino)-5,6,7,8-tetrahydro-4H-cyclohepta[b]thiophene-3-carboxylate and their Cr(III) and Zn(II) complexes have been synthesized. All of these substances have been examined for antibacterial activity against pathogenic strains Listeria monocytogenes 4b (ATCC-19115), Staphylococcus aureus (ATCC25923), Proteus OX2 Wrah (ETS.40-A-4), Escherichia coli (ATCC-1280), Salmonella typhi H (NCTC-901.8394), Pseudomonas putida sp., Brucella abortus (A.99, UK-1995) RSKK-03026. Sh. boydii type 11 (Pasteur51.6), Sh. boydii type 16 (cHe 67.11), Sh. boydii type 6 (RSKK-96043), and antifungal activity against Candida albicans (Y-1200-NIH, Tokyo). Some of the compounds exhibited activity comparable to ampicillin ofloxacin, nystatin, kanamycin, sulphamethoxazol, amoxycillin, and chloroamphenicol. Most of the studied compounds were found effective against bacteria studied and yeast.

Listeria sp. EM AFLUENTES E EFLUENTES DE MATADOUROS FRIGORÍFICOS DE BOVINOS EM GOIÁS

One hundred and forty samples of wastewater from two bovine slaughterhouses were microbiologically analysed. Only one of the slaughterhouses had treatment system LSAB and LPM medium Listeria innocua 4ab, Listeria innocua not defined serologically, Listeria innocua 6b, Listeria monocytogenes 4e, Listeria monocytogenes 4b, Listeria monocytogenes 1/2b and Listeria grayi were isolated.

Development of a sandwich ELISA for the detection of Listeria spp. using specific flagella antibodies

Five monoclonal antibodies (MAbs) and chicken immunoglobulin (IgY) were developed by immunizing with flagella purified from Listeria monocytogenes 4b and the five MAbs have been confirmed to be specific against three different epitopes of flagellin. The antibodies showed specific reaction to Listeria genus and no cross-reactivity with other bacteria tested in this experiment including E.coli O157:H7 and Salmonella enteritidis. Sandwich enzyme-linked immunosorbent assays (ELISA) using the MAbs and IgY were developed to detect Listeria species and the sensitivity and specificity of the developed ELISA have been analyzed. The detection limit of ELISA using MAb 2B1 and HRP labeled IgY was 1 x 10(5) cells/0.1 ml at 22 degrees C. and 1 x 10(6) cells/0.1 ml at 30 degrees C. ELISA using the pair of MAbs (MAbs 2B1 and HRP labeled MAbs 7A3) detected up to 10(4) cells/0.1 ml at 22 degrees C and 30 degrees C. Detection limit of sandwich ELISA using IgY was 10 times lower than MAb pair. Using the developed ELISA, we could detect several Listeria contaminated in food samples after 48 h-culturing. In conclusion, both MAbs and IgY have been proved to be highly specific to detect Listeria flagella and the developed sandwich ELISA using these antibodies would be useful tool for screening Listeria spp. in food.

Survival of Escherichia coli O157:H7, Listeria monocytogenes 4b and Yersinia enterocolitica O3 in different yogurt and kefir combinations as prefermentation contaminant.

To compare microbiological safety of yogurt, kefir and different combinations of yogurt and kefir samples by using three foodborne pathogenic strains (Escherichia coli O157:H7, Listeria monocytogenes 4b and Yersinia enterocolitica O3) as indicators. Fresh yogurt and kefir drinks were added to pasteurized milk at a 5% rate either separately or together, and then incubated at different temperatures (43 degrees C for yogurt and 30 degrees C for kefir), depending on appropriate growth temperature of their starter microflora. While traditional yogurt was found to be the least suppressive on the three pathogenic micro-organisms, samples obtained from two subsequent fermentation process (samples fermented at 43 degrees C for 3 h and at 30 degrees C for 21 h) were more suppressive than that of traditional kefir. There was no significant survival difference between E. coli O157:H7 and L. monocytogenes 4b in samples tested (P > 0.05), but Y. enterocolitica O3 was more susceptible than other two test strains (P < 0.05). The microbiological safety of the dairy product fermented at two consecutive periods was superior than that of traditional yogurt or kefir alone. These experiments may mimic what happens when yogurt and kefir starter micro-organisms are combined in a milk fermentation process with different time and temperature periods.

Survival of Escherichia coli O157:H7, Listeria monocytogenes 4b and Yersinia enterocolitica O3 in ayran and modified kefir as pre- and postfermentation contaminant

The survival of Escherichia coli O157:H7, Listeria monocytogenes 4b and Yersinia enterocolitica O3 in traditional yogurt and kefir during fermentation, in ayran (a dairy beverage in Turkey), pasteurised (long-life) ayran, modified kefir (salted and diluted kefir) and pasteurised modified kefir during cold storage were investigated. Pasteurised samples were used to monitor the antibacterial effect of natural flora of yogurt and kefir during cold storage. Populations of all the strains were increased during fermentation, and thus pre-fermentation contamination appeared more rhisky than postfermentation contamination. Pasteurisation appeared not to be disaadventageous an application on the microbiological safety of the samples, neverthelessbiological benefits which may come from live microorganisms is lost. While E. coli O157:H7 and L. monocytogenes 4b survived for up to 21 days in all samples, Y. enterocolitica O3 survived only for 14 days in modified kefir. Yogurt microflora appeared to be more suppressive on the pathogens than that of kefir.