Growth, biofilm formation, and motility of Listeria monocytogenes strains isolated from food and clinical samples located in Shanghai (China).

Listeria monocytogenes is a common foodborne pathogen that frequently causes global outbreaks. In this study, the growth characteristics, biofilm formation ability, motility ability and whole genome of 26 L. monocytogenes strains isolated from food and clinical samples in Shanghai (China) from 2020 to 2022 were analyzed. There are significant differences among isolates in terms of growth, biofilm formation, motility, and gene expression. Compared with other sequence type (ST) types, ST1930 type exhibited a significantly higher maximum growth rate, the ST8 type demonstrated a stronger biofilm formation ability, and the ST121 type displayed greater motility ability. Furthermore, ST121 exhibited significantly high mRNA expression levels compared with other ST types in virulence genes mpl, fbpA and fbpB, the quorum sensing gene luxS, starvation response regulation gene relA, and biofilm adhesion related gene bapL. Whole-genome sequencing (WGS) analyses indicated the isolates of lineage I were mostly derived from clinical, and the isolates of lineage II were mostly derived from food. The motility ability, along with the expression of genes associated with motility (motA and motB), exhibited a significantly higher level in lineage II compared with lineage I. The isolates from food exhibited significantly higher motility ability compared with isolates from clinical. By integrating growth, biofilm formation, motility phenotype with molecular and genotyping information, it is possible to enhance comprehension of the association between genes associated with these characteristics in L. monocytogenes.

Clinical Outcome and Factors with Dietary Behaviors in Pregnant Women with Listeria monocytogenes: A Hospital-Based Case-Control Study in Shanghai.

Listeriosis is a globally rare foodborne disease that causes fetal-placental infection, leading to adverse pregnancy outcome, while limited research among pregnant women is available in China. This study was therefore aimed at analyzing the incidence, clinical manifestations, and clinical outcome of listeriosis among pregnant women and its associated dietary behavior risk factors in prevention. A hospital-based case-control study had been conducted from January 2017 to December 2021. Clinical data, laboratory information, and questionnaires including dietary behaviors and personal hygiene were collected within 2 days after case diagnosis. There were 48 pregnant women, including 12 cases and 36 controls, with an average age of 31.19 ± 3.75 years. The incidence of admission-based listeriosis among pregnant women was 1.6058 per 10,000. The 12 strains were divided into 3 serotypes: 1/2a(83.33%), 1/2b(8.33%), and 4b(8.33%). Among the cases, 5 cases (41.67%) resulted in abortion, 3 cases (25%) induced preterm labor, and 4 cases (33.33%) had full-term deliveries after treatment. There were 7 live births in the case group, among which 6 were admitted to the neonatal intensive care unit (NICU), while 1 case had a healthy fetal outcome. All patients in the control group gave birth to live fetuses. Epidemiological investigation revealed that pregnant women dining at restaurants three or more times per week might increase the risk of having Listeria infection. There were no significant differences in dietary consumed behaviors, hand hygiene, and refrigerator usage behaviors between case and control groups. The study suggested that dining at restaurants might be associated with Listeria infection among pregnant women. Therefore, it is essential to enhance education on listeriosis serious consequences and promote healthy dietary and hygiene habits among pregnant women.

Risk factors associated with food consumption and food-handling habits for sporadic listeriosis: a case-control study in China from 2013 to 2022.

The prevalence of listeriosis in China has been increasing in recent years. Listeriosis primarily spreads through contaminated food. However, the resilient causative organism, Listeria monocytogenes, and its extended incubation period pose challenges in identifying risk factors associated with food consumption and food-handling habits. This study aimed to identify the risk factors associated with food consumption and food-handling habits for listeriosis in China. A matched case-control study (1:1 ratio) was conducted, which enrolled all eligible cases of listeriosis between 1 January 2013 and 31 December 2022 in China. Basic information and possible risk factors associated with food consumption and food-handling habits were collected. Overall, 359 patients were enrolled, including 208 perinatal and 151 non-perinatal cases. Univariate and multivariable logistic analyzes were performed for the perinatal group. For the perinatal and non-perinatal groups, ice cream and Chinese cold dishes were the high-risk foods for listeriosis (odds ratio (OR) 2.09 95% confidence interval (CI): 1.23-3.55; OR 3.17 95% CI: 1.29-7.81), respectively; consumption of leftovers and pet ownership were the high-risk food-handling habits (OR 1.92 95% CI: 1.03-3.59; OR 3.00 95% CI: 1.11-8.11), respectively. In both groups, separation of raw and cooked foods was a protective factor (OR 0.27 95% CI: 0.14-0.51; OR 0.35 95% CI: 0.14-0.89), while refrigerator cleaning reduced the infection risk by 64.94-70.41% only in the perinatal group. The identification of high-risk foods and food-handling habits for listeriosis is important for improving food safety guidelines for vulnerable populations.

Whole-Genome Sequencing-Based Characterization of Clinical Listeria monocytogenes Isolates in China, 2013-2019.

Invasive listeriosis is a rare but serious foodborne disease that causes maternal-neonatal, central nervous system, and bloodstream infections. The aim of this study was to assess the whole-genome sequencing (WGS)-based genetic diversity of clinical Listeria monocytogenes isolates over a 7-year period and prove the effect of WGS application in food vehicle investigation. A total of 360 isolates were recovered during 2013 and 2019 through the national listeriosis special surveillance program. Two hundred twenty-six isolates (62.8%) were associated with pregnancy. All isolates belonged to lineage I (214 isolates) or lineage II (146 isolates), with 4 serogroups (46.9% IIb, 39.7% IIa, 12.5% IVb, and 0.8% IIc). All isolates were in 25 clonal complexes (CCs) and 3 singletons, with CC87, CC8, and CC5 being the most common causes of human listeriosis. All clinical isolates were positive for Listeria pathogenicity island 1 (LIPI-1), LIPI-3 was present in 21.4% of isolates and LIPI-4 was detected in 29.2% of isolates. LIPI-4-positive isolates, including CC87, sequence type (ST)619, ST382, CC4, and CC2, have been shown to confer hypervirulence. Fifteen isolates harbored at least one antimicrobial encoding gene, including tet (M), mef (A), msr (D), and dfr (G). The sublineage designations were consistent with CC designations, and 215 distinct cgMLST types (CTs) were classified, the most abundant being CT58 and CT750. In summary, there is a high level of genetic diversity among the clinical isolates. WGS has strengthened listeriosis surveillance and will be implemented for other foodborne bacteria in the National Molecular Tracing Network for Foodborne Disease.

Identification of Listeria monocytogenes Contamination in a Ready-to-Eat Meat Processing Plant in China.

Listeria monocytogenes is the etiologic agent of listeriosis, which remains a significant public health concern in many countries due to its high case-fatality rate. The constant risk of L. monocytogenes transmission to consumers remains a central challenge in the food production industry. At present, there is very little known about L. monocytogenes contamination in ready-to-eat (RTE) processing plants in China. In this study, L. monocytogenes in an RTE meat processing plant in Shanghai municipality was characterized using pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). Furthermore, the biofilm formation ability of the pathogen was also tested. Results revealed that L. monocytogenes isolates were present in 12 samples out of the 48 samples investigated. Most of them (66.7%, 8/12) were identified from the processing facilities irrespective of observed hygiene levels of aerobic plate count (APC) and coliforms. Coliforms were present in only one processing area. ST5 (1/2b) isolates were predominant (83.3%, 10/12) and were identified in two dominant pulsotypes (PTs) (three in PT3 and seven in PT4, respectively). Results of the core-genome multi-locus sequence typing (cgMLST) showed that ST5 in three PTs (PT1, PT3, and PT4) had 0-8 alleles, which confirmed that clonal transmission occurred in the RTE meat processing facilities. In addition, the biofilm formation test confirmed that the isolates from the processing facilities could form biofilms, which helped them colonize and facilitate persistence in the environment. These results indicated that common sanitation procedures regularly applied in the processing environment were efficient but not sufficient to remove L. monocytogenes isolates, especially biofilm of L. monocytogenes. Furthermore, the ST5 isolates in this study exhibited 12 alleles with one ST5 clinical isolate, which contributes to the understanding of the potential pathogenic risk that L. monocytogenes in RTE meat processing equipment posed to consumers. Therefore, strong hygienic measures, especially sanitation procedures for biofilms eradication, should be implemented to ensure the safety of raw materials. Meanwhile, continuous surveillance might be vital for the prevention and control of listeriosis caused by L. monocytogenes.

Functional divergence and adaptive selection of KNOX gene family in plants.

KNOTTED-like homeodomain (KNOX) genes are transcriptional regulators that play an important role in morphogenesis. In the present study, a comparative analysis was performed to investigate the molecular evolution of the characteristics of the KNOX gene family in 10 different plant species. We identified 129 KNOX gene family members, which were categorized into two subfamilies based on multiple sequence alignment and phylogenetic tree reconstruction. Several segmental duplication pairs were found, indicating that different species share a common expansion model. Functional divergence analysis identified the 15 and 52 amino acid sites with significant changes in evolutionary rates and amino acid physicochemical properties as functional divergence sites. Additional selection analysis showed that 14 amino acid sites underwent positive selection during evolution, and two groups of co-evolutionary amino acid sites were identified by Coevolution Analysis using Protein Sequences software. These sites could play critical roles in the molecular evolution of the KNOX gene family in these species. In addition, the expression profiles of KNOX duplicated genes demonstrated functional divergence. Taken together, these results provide novel insights into the structural and functional evolution of the KNOX gene family.

10-Year Molecular Surveillance of Listeria monocytogenes Using Whole-Genome Sequencing in Shanghai, China, 2009-2019.

Listeria monocytogenes is an etiologic agent of listeriosis, and has emerged as an important foodborne pathogen worldwide. In this study, the molecular characteristics of 155 L. monocytogenes isolates from seven food groups in Shanghai, the biggest city in China, were identified using whole-genome sequencing (WGS). Most L. monocytogenes isolates (79.3%) were obtained between May and October from 2009 to 2019. The serogroups and clonal complexes (CCs) of L. monocytogenes were found useful for identifying potential health risks linked to foods. Differences in distributions of serogroups and CCs among different food groups were analyzed using t-test. The results showed that the IIa and IVb serogroups were identified among most of food groups. However, the prevalence of serogroup IIb was significantly higher in ready-to-eat (RTE) food and raw seafood than in other food groups, similar to group IIc in raw meat and raw poultry than others. Meanwhile, the prevalence of CC9 in raw meat and raw poultry, CC8 in raw poultry, and CC87 in raw seafood significantly exceeded that of in other food groups. Specially, CC87 was the predominant CC in foodborne and clinical isolates in China, indicating that raw seafood may induce a high-risk to food safety. Also, hypervirulence pathogenicity islands LIPI-3 and LIPI-4 were found in CC3, CC1, and CC87, respectively. The clonal group CC619 carried LIPI-3 and LIPI-4, as previously reported in China. Core genome multilocus sequence typing (cgMLST) analysis suggested that CC87 isolates from the same food groups in different years had no allelic differences, indicating that L. monocytogenes could persist over years. These 10-year results in Shanghai underscore the significance of molecular epidemiological surveillance of L. monocytogenes in foodborne products in assessing the potential risk of this pathogen, and further address food safety issues in China.

Urinary levels of nickel and chromium associated with dental restoration by nickel-chromium based alloys.

This paper aims to investigate if the dental restoration of nickel-chromium based alloy (Ni-Cr) leads to the enhanced excretions of Ni and Cr in urine. Seven hundred and ninety-five patients in a dental hospital had single or multiple Ni-Cr alloy restoration recently and 198 controls were recruited to collect information on dental restoration by questionnaire and clinical examination. Urinary concentrations of Ni and Cr from each subject were measure by graphite furnace atomic absorption spectrometry. Compared to the control group, the urinary level of Ni was significantly higher in the patient group of <1 month of the restoration duration, among which higher Ni excretions were found in those with either a higher number of teeth replaced by dental alloys or a higher index of metal crown not covered with the porcelain. Urinary levels of Cr were significantly higher in the three patient groups of <1, 1 to <3 and 3 to <6 months, especially in those with a higher metal crown exposure index. Linear curve estimations showed better relationships between urinary Ni and Cr in patients within 6-month groups. Our data suggested significant increased excretions of urinary Ni and Cr after dental restoration. Potential short- and long-term effects of Ni-Cr alloy restoration need to be investigated.

[A cross-sectional survey on immunological function after dental restoration of nickel-chromium alloy].

OBJECTIVE: To investigate the immunological function parameters in patients undergoing dental restoration of nickel-chromium (Ni-Cr). METHODS: Seven hundred and ninety-five Ni-Cr alloy consumers as exposure group, together with 198 controls, were surveyed by the questionnaire and the biological examination of immunological function. RESULTS: After splitting all subjects into three groups of equal sample size by urinary Ni or urinary Cr, serum interleukin-1beta(IL-1ß) was found to be significantly higher in the group of urinary Ni > 115.73 µg/mol creatinine comparing to the group of urinary Ni < 37.28 µg/mol creatinine (P < 0.05). No changes of immunological parameters in surm [tumor necrosis factor-alpha (TNF-α), IL-1ß, and IL-6] were found in other groups of urinary Ni or Cr. Both one way analysis of variance (ANOVA) and linear regression analysis did not find any association between serum changes of immunological parameters and the parameters of alloy restoration (period, number and the level of metal crown uncovered with porcelain). CONCLUSIONS: This study did not show positive associations between dental restoration of Ni-Cr alloy and serum levels of TNF-α, IL-1ß and IL-6.

[A prospective follow-up study on the impact of urinary excretions of nickel and chromium after dental restoration by nickel-chromium based alloys].

OBJECTIVE: To explore whether the dental restoration of nickel-chromium (Ni-Cr) based alloys will lead to extra excretions of urinary Ni and Cr. METHODS: Urinary Ni and Cr were repeatedly measured in 33 patients before and 2 months after the dental restoration of Ni-Cr alloys. The associations between alloy restoration and urinary Ni or Cr were analyzed by paired t test and general linear model of repeated measures. RESULTS: A slightly higher urinary Ni was found in patients after 2 month of the alloy restoration, but the difference was not statistically significant (before: 46.4 microg x mol(-1) crea; after: 67.6 microg x mol(-1) crea; P=0.063). This difference was only in female subjects (before: 44.8 microg x mol(-1) crea; after: 73.7 microg x mol(-1) crea; P=0.068). A significant higher urinary Cr was found in patients after 2 month of the alloy restoration (before: 57.0 microg x mol(-1) crea; after: 99.4 microg x mol(-1) crea; P=0.024). This significant difference was only in female subjects (before: 59.8 microg x mol(-1) crea; after: 124.4 microg x mol(-1) crea; P=0.023). General linear models of repeated measurements showed that urinary excretions of Ni and Cr were associated with the number of restoration and the area of metal basis uncovered with porcelain. CONCLUSION: Dental restoration of Ni-Cr alloy might lead to the enhanced excretions of urinary Ni and Cr.