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Listeria monocytogenes is a foodborne pathogen with a high mortality rate in humans. This study aimed to identify the pathogenic potential of L. monocytogenes isolated from ready-to-eat (RTE) foods and pasteurized milk in China on the basis of its phenotypic and genotypic characteristics. Approximately 7.7% (44/570) samples tested positive for L. monocytogenes among 10.8% (39/360) RTE and 2.4% (5/210) pasteurized milk samples, of which 77.3% (34/44) had < 10 MPN/g, 18.2% (8/44) had 10–110 MPN/g, and 4.5% (2/44) had > 110 MPN/g. A total of 48 strains (43 from RTE foods and five from milk samples) of L. monocytogenes were isolated from 44 positive samples. PCR-serogroup analysis revealed that the most prevalent serogroup was II.2 (1/2b-3b-7), accounting for 52.1% (25/48) of the total, followed by serogroup I.1 (1/2a-3a) accounting for 33.3% (16/48), serogroup I.2 (1/2c-3c) accounting for 12.5% (6/48), and serogroup II.1 (4b-4d-4e) accounting for 2.1%. All isolates were grouped into 11 sequence types (STs) belonging to 10 clonal complexes (CCs) and one singleton (ST619) via multi-locus sequence typing. The most prevalent ST was ST87 (29.2%), followed by ST8 (22.9%), and ST9 (12.5%). Virulence genes determination showed that all isolates harbored eight virulence genes belonging to Listeria pathogenicity islands 1 (LIPI-1) (prfA, actA, hly, mpl, plcA, plcB, and iap) and inlB. Approximately 85.4% isolates carried full-length inlA, whereas seven isolates had premature stop codons in inlA, six of which belonged to ST9 and one to ST5. Furthermore, LLS (encoded by llsX gene, representing LIPI-3) displays bactericidal activity and modifies the host microbiota during infection. LIPI-4 enhances neural and placental tropisms of L. monocytogenes. Results showed that six (12.5%) isolates harbored the llsX gene, and they belonged to ST1/CC1, ST3/CC3, and ST619. Approximately 31.3% (15/48) isolates (belonging to ST87/CC87 and ST619) harbored ptsA (representing LIPI-4), indicating the potential risk of this pathogen. Antimicrobial susceptibility tests revealed that > 95% isolates were susceptible to 16 antimicrobials; however, 60.4 and 22.9% isolates were intermediately resistant to streptomycin and ciprofloxacin, respectively. The results show that several isolates harbor LIPI-3 and LIPI-4 genes, which may be a possible transmission route for Listeria infections in consumers.

Background: Emerging evidence suggested phytosterol esters (PE) exhibited an advantage over naturally occurring phytosterols in reducing atherosclerosis risk factors due to improved fat solubility and compatibility. However, the effects of dietary patterns of PE on lipid-lowering activity were limited and inconsistent. This study aimed to explore the effects of dose and frequency of α-linolenic acid rich phytosterol esters (ALA-PE) on cholesterol and triglyceride metabolism markers focused on intestinal cholesterol absorption and bioconversion of ALA in liver. Methods: Dose-dependency study Male Syrian golden hamsters were fed high-fat diets (HFD) containing low, medium and high dose of ALA-PE (0.72 %, 2.13 % and 6.39 %) for 6 weeks. The high fat diet contained 89.5 % chow diet, 0.2 % cholesterol, 10 % lard and 0.3 % bile salt. Dose-frequency study Male Syrian golden hamsters were provided: (I) 0.4 mL/100 g peanut oil by gavage once a day; (II) 0.4 mL/100 g ALA-PE by gavage once a day; (III) 0.2 mL/100 g ALA-PE by gavage twice a day; (IV) 0.133 mL/100 g ALA-PE by gavage three times a day; (V) 0.1 mL/100 g ALA-PE by gavage four times a day for 6 weeks with a high-fat diet simultaneously. Results: ALA-PE dose-dependently lowered plasma total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) concentrations with a maximal decrease of 42 %, 59 % and 73 %, respectively (p < 0.05). Compared to HFD, TC, LDL-C and TG concentrations were significantly lower (p < 0.01) in hamsters consumed HFD plus ALA-PE for 1-4 times per day but there were not remarkable differences among different consumption frequencies. No significant changes in plasma antioxidant capacity and lipid peroxidation levels were observed among HFD and HFD plus different doses of ALA-PE groups. The contents of hepatic α-linolenic (ALA), docosapentaenoic (DPA) and docosahexaenoic (DHA) acids were dose-dependently increased in different ALA-PE groups compared to those in HFD group. The abundance of mRNA for intestinal sterol transporters Niemann-Pick C1-Like 1 (NPC1L1), ATP-binding cassette (ABC) transporters ABCG5 and ABCG8 indicated no significant differences among all groups. Conclusion: ALA-PE dose-dependently improved lipid profile in hamsters fed HFD independent of intestinal ABCG5, ABCG8 and NPC1L1, accompanying by increased conversion of ALA to DPA and DHA in liver. ALA-PE manifested "once a day" lipid-lowering efficacy, highlighting a promising preventive strategy for metabolic syndrome. [ABSTRACT FROM AUTHOR]