No abstract available.
Listeria monocytogenes* ; Listeria* ; Macrophages* ; Salmonella typhimurium* ; Salmonella*

Aims: This study was designed to evaluate the effectiveness of the synthesised carvacrol loaded chitosan nanoparticles (CLCNPs) on the growing and pre-formed biofilms of Listeria monocytogenes isolated from slaughterhouses. Methodology and results: The swab samples were collected from knives, hocks and cutting tables representing slaughterhouses meat contact surfaces (MCS), while those samples from walls and floors represent slaughterhouses meat non-contact surfaces (MNCS). The bacteriological analysis revealed the existence of L. monocytogenes with a prevalence rate of 3.3, 10 and 6.7% for knives, hocks and cutting tables, respectively and 2.2 and 6.6% for walls and floors, respectively. The isolates L. monocytogenes were assayed for biofilm production by the crystal violet binding assay method. Among the 10 L. monocytogenes isolates, 10%, 50% and 30% of the isolates were found to be strong, moderate and weak biofilm producers, respectively. The activities of carvacrol, chitosan nanoparticles (NPs) and CLCNPs against the only strong biofilm producer strain of L. monocytogenes were tested by microtiter plate assay. The minimum inhibitory concentrations (MIC) values were 3.75 mg/mL for CAR, 5 mg/mL for chitosan NPs and 0.62 mg/mL for CLCNPs. CLCNPs inhibit the produced biofilm by 35.79, 73.37 and 77.76%, when 0.5 MIC, 1 MIC and 2 MIC were used, respectively. Furthermore, the pre-formed L. monocytogenes biofilms were significantly reduced from 1.01 (control) OD570 to 0.40 and 0.29 OD570 by applying 2 MIC and 4 MIC doses, respectively. Conclusion, significance and impact of study The data generated is promising to develop bio-green disinfectants to inhibit biofilm formation by L. monocytogenes in the food processing environment and control its adverse effects for consumers.
Chitosan--chemistry ; Listeria monocytogenes ; Nanoparticles

No abstract available.
Arthritis ; Bacteremia* ; Female* ; Humans ; Knee Joint* ; Knee* ; Listeria monocytogenes* ; Listeria*

No abstract available.
Child* ; Humans ; Listeria monocytogenes ; Listeria* ; Listeriosis* ; Meningitis ; Sepsis

Listeria monocytogenes is an important food-borne pathogen. The distribution and survival of L. monocytogenes are related to its ability to form biofilms. Biofilms are resistant to adverse environments, and bacteria separated from the biofilms may lead to persistent food contaminations. The formation, maturation and structure of biofilms depend on a variety of external and internal factors, among which a variety of regulatory mechanisms play important roles. This review summarizes the regulatory mechanisms (including intracellular, intercellular and interspecific interactions) involved in the biofilm formation of L. monocytogenes in order to control the biofilm formation in food processing environments, thus providing new intervention strategy for food safety.
Biofilms ; Food Contamination ; Food Safety ; Listeria monocytogenes

Aims: This study aims to isolate lactic acid bacteria (LAB) from various food sources to obtain a potent strain against Listeria monocytogenes. Methodology and results: A total of 68 LAB isolates were selected to evaluate their antimicrobial activity against L. monocytogenes, a foodborne pathogen and a causative agent of listeriosis. The selected isolate was identified and characterized. The isolate C23 from cabbage showed the highest antimicrobial activity against L. monocytogenes ATCC 7644 with inhibition ability of 73.94%. The isolate was closely related to Lactobacillus brevis by 16S rRNA sequencing and subsequently deposited in GenBank with an accession number of MN880215, named as L. brevis C23. The cell free supernatant (CFS) of L. brevis C23 had high tolerance in low pH and was able to withstand up to 60 °C. The proteinaceous nature of the antimicrobial agent was also confirmed through the enzymatic test. The CFS was stable on different detergents as well as bile salts. Under transmission electron microscopy (TEM), the inhibitory effect of CFS against L. monocytogenes was proven by causing cell lysis. Conclusion, significance and impact of study Bacteriocin-like inhibitory substances (BLIS) of L. brevis C23 showed very promising potential in food industrial application.
Lactobacillales ; Listeria monocytogenes ; Foodborne Diseases ; Sprains and Strains

Two terpenoids, including one uniquely aromatized one (1), were isolated from CH2Cl2-soluble fraction of MeOH extracts of Curcuma zedoaria. They were identified to be a sesquiterpene ketolactone (1) and orobanone (2), respectively on the basis of their NMR data. The structure of compound 1 was confirmed by X-ray chrystallography and the reported NMR assignments for 1 were revised in this study. Antibiotic activities for compounds 1 and 2 were evaluated using disk diffusion assay. Compound 1 showed potent antibacterial activities against Listeria monocytogenes and Staphylococcus pseudointermedius while compound 2 was active against Bacillus cereus.
Bacillus cereus ; Curcuma* ; Diffusion ; Listeria monocytogenes ; Rhizome* ; Staphylococcus ; Terpenes ; Zingiberaceae

Strain variability is one of the most important factors to influence the accuracy of foodborne pathogens risk assessment, such as Listeria monocytogenes, Salmonella spp. Strain-to-strain variation is defined as the inherent differences among identically treated strains of the same microbial species. The differences cannot be eliminated by changing test methods or improving test protocols. This review addresses presently related studies of strain variability. Based on the effect of strain variability on the outcome of risk assessment, we summarize sources of variabilities in food chain, strain phenotypic variabilities and the methods to integrate strain variability in growth and inactivation into predictive modelling, and indicate the inadequacies in the study of strain variability. We suggest further study the mechanism of strain variability, expand the comparison of variability among different sources, and integrate the variability of gene expression, protein and cell metabolism into the predictive modelling.
Food Microbiology ; Listeria monocytogenes/genetics* ; Risk Assessment ; Salmonella/genetics*

The invariant (i) natural killer (NK)T cells represent a unique subset of T lymphocytes which express the V alpha14 chain of the T cell receptor (TCR), that recognizes glycolipid antigens presented by the nonpolymorphic major histocompatibility complex (MHC) class I-like antigen presentation molecule CD1d, and they participate in protection against some microbial pathogens. Although iNKT cells have originally been regarded as T cells co-expressing NKR-P1B/C (NK1.1: CD 161), they do not seem to consistently express this marker, since NK1.1 surface expression on iNKT cells undergoes dramatic changes following facultative intracellular bacterial infection, which is correlated with functional changes of this cell population. Accumulating evidence suggests that NK1.1 allows recognition of "missing-self", thus controling activation/inhibition of NK1.1-expressing cells. Therefore, it is tempting to suggest that iNKT cells participate in the regulation of host immune responses during facultative intracellular bacterial infection by controlling NK1.1 surface expression. These findings shed light not only on the unique role of iNKT cells in microbial infection, but also provide evidence for new aspects of the NK1.1 as a regulatory molecule on these cells.
Animals ; Humans ; Listeria Infections/*immunology ; Listeria monocytogenes/*immunology ; Natural Killer T-Cells/*immunology/*microbiology

Three Listeria monocytogenes strains isolated from clinical cerebrospinal fluid samples. A PCR was performed by using oligonuclotide primers derived from the invasion-associated protein(iap) related gene sequence. As a result of PCR, we obtained 287-bp DNA fragment of specific product to L. monocytogenes species. The chromsomal DNA of genera Listeria species were subjected to southern blot hybridization with HRP-labeled 287-bp DNA probe to produce a L. monocytogenes banding pattern. In the cases of 10-fold dilution of L. monocytogenes cells, 8 x 10(2) cells/ml were detected by PCR.
Blotting, Southern ; Cerebrospinal Fluid ; DNA ; Listeria monocytogenes* ; Listeria* ; Polymerase Chain Reaction*