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Objectives: Using a sporadic case of listeriosis suspected to have been caused by consuming a pre-packaged cold-chain ready-to-eat (RTE) food in Beijing, China in 2021 as an exemplar, this study demonstrated the importance of thoroughly investigating the source of listeriosis up to the production point for mitigating infection risk during routine monitoring of Listeria in food facilities and national surveillance program using whole-genome sequencing (WGS)., Methods: Epidemiological, laboratory, traceback, and plant investigations were used to identify the source of infection., Results: WGS showed the isolate from the patient was genetically indistinguishable from that of the implicated food. During a plant investigation, L. monocytogenes was detected in 26% (9/35) of the environmental samples and one of two raw material samples, confirming the source., Conclusion: To our knowledge, this is the first investigation in China linking a case of L. monocytogenes infection to a suspected food and its production environment. This report highlights the risk of L. monocytogenes contamination of RTE food and demonstrates the role of food safety risk monitoring in identifying potential sources of infection. Reinforcing control programs in RTE processing plants, intensified surveillance of microorganisms in food products and targeted health education is required to mitigate the infection risk., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

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.

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.

Listeria monocytogenes is a foodborne pathogen. In 2022, we collected 15 strains of L. monocytogenes isolated from patients in some foodborne disease sentinel monitoring hospitals in Sichuan Province. Through whole genome sequencing (WGS), we obtained the virulence genes carried by the strains, multi-locus sequence typing (MLST), core genome MLST (cgMLST), clonal complex (CC), and serum groups and constructed a phylogenetic tree and minimum spanning tree with nonhuman strains. An analysis shows that all 15 strains of L. monocytogenes carry virulence genes LIPI-1 and LIPI-2 , whereas the carrying rates of LIPI-3 and LIPI-4 virulence genes are relatively low. The MLST typing results showed a total of 10 sequence types (ST), including 10 CCs, with ST7 being the dominant type. The cgMLST clearly distinguishes strains of different lineages and CC types. The serum group is divided into three types: IIa, IIb, and IVb, with IIa being the dominant serum group. An analysis of antibiotic genes showed that all 15 strains carried FosX , lin , mprF , and norB with high carrying rates. The minimum inhibitory concentration results indicated that all were susceptible to eight antibiotics (ampicillin, penicillin, tetracycline, meropenem, erythromycin, vancomycin, ciprofloxacin, and trimethoprim-sulfamethoxazole). The analysis of strains isolated from different sources of Listeria revealed varying degrees of diversity, and the contamination of meat and environment within the province is closely related to clinical cases. L. monocytogenes isolated from clinical cases in Sichuan Province carry multiple virulence and antibiotic genes, with high potential pathogenicity. It is necessary to further strengthen the monitoring and control of food and environment by L. monocytogenes within Sichuan Province.

Listeria monocytogenes ( Lm ) is associated with severe foodborne infections and ubiquitous in the nature. Identification of characteristics of Lm transmission through trading of food products is essential for rapidly tracking Lm sources and controlling dissemination of listeriosis. In this study, a total of 44 Lm strains were isolated from food products originating from 14 countries/regions during 2003-2018 at the Shanghai port. The genomes of these Lm strains were sequenced by high-throughput sequencing. Multilocus sequence typing (MLST) analysis showed that 43 isolates were divided into 17 sequence types (STs). The distribution of STs was decentralized, with the dominant ST2 accounting for only 18.18% of the strains. The LM63 strain did not match with any of the existing STs. Core-genome MLST (cgMLST) analysis based on 1748 core genes categorized the 44 strains into 30 cgMLST types (CTs), with CT10153 and CT7892 as the most predominant CTs. Notably, LM63 and LM67 shared the same CT in the cgMLST analysis. The phylogenetic analysis based on single-copy homologous genes revealed that the 44 Lm strains were primarily classified into two lineages. The SNP analysis also indicated that these strains were roughly divided into two clades, with strains in the first clade mainly collected earlier than those in the second clade, which were predominantly collected from 2010 onwards. The analysis using the virulence factor database (VFDB) indicated that the virulence gene inlJ was the most prevalent among these 44 strains. Notably, ddrA , msbA , and sugC were enriched in this dataset, requiring further clarification of their roles in Listeria through future studies. These results might provide a clue for understanding of the global epidemiology and surveillance of Lm and present insights for implementing effective measures to reduce or prevent Listeria contamination outbreaks in imported food products., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhu, Ji, Wu, Xu, Wang and Huang.)

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.

A total of 1797 imported food samples collected during 2018 to 2020 were investigated for Listeria monocytogenes. Antibiotic susceptibility tests and whole genome sequencing analysis were performed for the obtained isolates. The overall prevalence of L. monocytogenes was 5.62 %; the highest prevalence was observed for pork (13.65 %), followed by fish (6.25 %), sheep casing (6.06 %), chicken (3.61 %), and beef (2.06 %). Geographical differences in prevalence were also observed for pork. Resistance to oxacillin (39.33 %) and clindamycin (16.85 %) was common, whereas resistance rates for other antibiotics were relatively low, ranging from 0 % to 6.74 %. Pork and fish isolates showed resistance to more antibiotics than beef isolates. Tetracycline and chloramphenicol resistance phenotypes strongly correlated with genotypes. The predominant serogroup was 1/2a, 3a, at 44.44 %, while the percentages of three other serogroups were similar and relatively lower, from 17.28 % to 19.75 %. Significant genetic differences were observed among lineage I and II isolates. LIPI-3 was carried by 19.75 % (16/81) of isolates and LIPI-4 by 6.17 % (5/81); all were lineage I. The stress survival island was present in 31.03 % (9/29) of lineage I and 83.02 % (44/53) of lineage II. Benzalkonium chloride tolerance genes were carried by 10.34 % (3/29) of lineage I and 23.08 % (12/52) of lineage II isolates. A total of 25 sequence types (STs) were identified, among which one was novel; ST9 and ST121 were the most prevalent. Disparate distribution of STs among food types was observed, and geographical and food related characteristics were also found for some STs. Hypervirulent STs, such as ST1, ST4 and ST6, belonged to 4b,4e,4e; carried LIPI-3 and/or LIPI-4; and some even were ECI or ECII; while only one carried SSI or BC tolerance genes. In contrast, hypo-virulent STs such as ST9 and ST121 carried SSI and BC tolerance genes, while none had LIPI-3/LIPI-4. Certain STs were detected frequently from a particular food of a particular country for a long time, indicating more attention should be given to these special persistent isolates. These findings are valuable for source tracking, prevention and control of L. monocytogenes in the global food chain., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests. All authors have reviewed and agreed with the contents of the manuscript. It is original work and has not been submitted to any other journals for publication., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Objective: Listeriosis is a foodborne disease that occurs in immunocompromised patients. Pregnant women are a high-risk group for the disease. Listeria infection during pregnancy is uncommon in China because of dietary habits, with little clinician attention and minimal therapeutic options due to its population-specific nature.This article studies the clinical characteristics of Listeria infection in pregnant women and the improvement of treatment methods., Subjects: This study collected clinical data from 16 cases of pregnant patients with laboratory-confirmed Listeria monocytogenes infections at the Women and Children's Hospital of Jiaxing University. These data were combined with 77 cases that were reported in the literature for a total of 93 cases of Listeria monocytogenes infection in pregnancy that occurred in China over a 15-year interval., Methods: We collected the clinical data of 16 pregnant patients with listeriosis diagnosed in the laboratory of the Women and Children's Hospital of Jiaxing University from May 2013 to December 2020, and combined it with 77 cases of Listeria monocytogenes during pregnancy in China obtained from a literature search. We summarized the clinical features of listeriosis in pregnancy infection and investigated its treatment methods and prevention., Results: Ninety-three cases of Listeria monocytogenes infection in pregnancy occurred in early, middle and late pregnancy in 31, 27, and 35 patients, respectively. The initial clinical presentation was fever in 90 patients, intermittent lower abdominal pain in 50 patients, and abnormal fetal movement and/or abnormal fetal heartbeat in 27 cases. Specimens with a positive bacterial culture included the following: 6 amniotic fluid cultures, 35 blood cultures, 37 maternal placenta and uterine secretion cultures, and 15 neonatal blood cultures. Fifty-seven cases of placental pathology, all showing of neutrophil infiltration, were 100% consistent with acute chorioamnionitis. Fifty-eight patients were initially treated with cephalosporin antibiotics, and only 24 cases were initially treated with broad-spectrum penicillins to cover the pathogenic bacteria. Drug sensitivity tests revealed resistant strains, 15 penicillin G-resistant, 14 oxacillin-resistant, and 13 ampicillin-resistant strains. After penicillin failure, vancomycin or meropenem was given. Maternal outcomes included the following: 20 cases of sepsis, 3 cases of pneumonia, 6 cases of acute pyelonephritis, 28 cases of intrauterine infection, 2 cases of multiple organ dysfunction syndromes, and 1 case of septic shock. The fetal and neonatal outcomes were as follows: 16 cases of abortion, 16 cases of intrauterine fetal death, 22 cases of death after birth, and 39 cases of cure., Conclusion: In our study and reported cases, Listeria monocytogenes in pregnancy is associated with fever as the primary manifestation, a high incidence of adverse pregnancy outcomes, and a significant increase in fetal and neonatal mortality. The low coverage of practical use of antimicrobial drugs and the emergence of drug-resistant strains in recent years have increased the difficulty of treatment, suggesting the need for clinicians to raise awareness of the disease and strengthen healthy diet promotion for women in pregnancy.

Listeria monocytogenes remains a significant public health threat, leading to invasive listeriosis with severe manifestations (i.e. septicemia, meningitis, and abortion) and up to 30% of fatal cases. Here, we aimed to investigate genotypic diversity, virulence profiles, antimicrobial resistance patterns from a large and integrated population of L. monocytogenes isolates in China (n = 369), including food (n = 326), livestock (n = 25), and hospitalized humans (n = 18) over the years (2002-2019). PCR-based serogrouping showed the dominance of serogroup 1/2a-3a (37.4%) in food, 4a-4c (76%) in livestock, and 1/2a-3a (44.4%) in humans. Phylogenetic lineage analysis revealed the dominance of lineage II (63.4%) in food, lineage III (76%) in livestock, and lineage II (55.5%) in humans. Altogether, 369 isolates were grouped into 55 sequence types (STs) via multi-locus sequence typing (MLST), which belonged to 26 clonal complexes (CCs) and 17 singletons. Among various STs, ST9 (26%) was the most abundant in food, ST202 (76%) in livestock, and ST8 (16.6%) in humans. Overall, ST4/CC4, ST218/CC218, and ST619 isolates harbored both LIPI-3 and LIPI-4 genes subsets indicating their hypervirulence potential. Additionally, a low resistance was observed towards tetracycline (5.1%), erythromycin (3.2%), cotrimoxazole (2.9%), chloramphenicol (2.7%), gentamicin (2.4%), and ampicillin (2.1%). Collectively, detection of hypervirulent determinants and antimicrobial-resistant phenotype among Chinese isolates poses an alarming threat to food safety and public health, which requires a continued and enhanced surveillance system for further prevention of human listeriosis., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Listeriosis, caused by Listeria monocytogenes , is a severe food-borne infection. The nationwide surveillance in China concerning listeriosis is urgently needed. In the present study, 144 L. monocytogenes isolates were collected from the samples of blood, cerebrospinal fluid (CSF), and fetal membrane/placenta in China for 12 years from 2008 to 2019. We summarized these listeriosis patients' demographical and clinical features and outcomes. The susceptibility profile for 12 antibiotics was also determined by the broth microdilution method. Multilocus sequence typing (MLST) and serogroups of these listeria isolates were analyzed to designate epidemiological types. We enrolled 144 cases from 29 healthcare centers, including 96 maternal-neonatal infections, 33 cases of bacteremia, 13 cases of neurolisteriosis, and two cutaneous listeriosis. There were 31 (59.6%) fetal loss in 52 pregnant women and four (9.8%) neonatal death in 41 newborns. Among the 48 nonmaternal-neonatal cases, 12.5% (6/48) died, 41.7% (20/48) were female, and 64.6% (31/48) occurred in those with significant comorbidities. By MLST, the strains were distinguished into 23 individual sequence types (STs). The most prevalent ST was ST87 (49 isolates, 34.0%), followed by ST1 (18, 12.5%), ST8 (10, 6.9%), ST619 (9, 6.3%), ST7 (7, 4.9%) and ST3 (7, 4.9%). Furthermore, all L. monocytogenes isolates were uniformly susceptible to penicillin, ampicillin, and meropenem. In summary, our study highlights a high genotypic diversity of L. monocytogenes strains causing clinical listeriosis in China. Furthermore, a high prevalence of ST87 and ST1 in the listeriosis should be noted., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Lu, Yang, Gao, Li, Cui, Huang, Chen, Wang, Wang, Liu, Li, Zhang, Jiao, Xu, Song, Fu, Xu, Yang, Ning, Wang, Bao, Luo, Wu, Yang, Li, Tang, Wang, Guo, Zeng and Zhong.)

Listeria monocytogenes is a deadly foodborne pathogen, and infections can result in meningoencephalitis and sepsis with mortality rates of up to 30%. In this study, we performed comparative whole-genome analysis of 30 clinical isolates sequenced together with 32 previously sequenced clinical and food isolates from China. The data indicate that L. monocytogenes isolates belonging to the clonal complexes (CC) -1, -8, -9, -87, -121, and -155 are present in human clinical cases. The majority of isolates are from CC-87, 9, and 8 and overlap with those CCs previously reported on the basis of multilocus sequence typing for isolates from Chinese food products. Detailed genome analysis of isolates, representative of CCs in clinical and food products, revealed strong similarities both in their core- and accessory genomes indicating that they are highly related. When compared to genome sequences of isolates of a given CC worldwide, clinical isolates of China were distinct and clustered in unified clades. Our data indicate that epidemic clones of L. monocytogenes (CC-87, 9, and 8) with unusually high occurrence of plasmids are unique to China and suggest that common populations of L. monocytogenes clones are present in both clinical and food products in China.

Objective: To analyze the molecular characteristics of Listeria monocytogenes strains from ready-to eat food in China. Methods: A total of 239 Listeria monocytogenes strains isolated from ready-to-eat food in 2017, all strains underwent whole-genome sequencing (WGS) , and comparisons uncovered population structure derived from lineages, clonal complex, serogroups, antimicrobial susceptibility and virulence, which were inferred in silico from the WGS data. Core genome multilocus sequence typing was used to subtype isolates. Results: All strains were categorized into three different lineages, lineage Ⅱ was the predominant types in food, and IIa was the main serogroups. CC8, CC101 and CC87 were the first three prevalent CCs among 23 detected CCs, accounting for 49.4%. Only 4.6% (11 isolates) of tested strains harbored antibiotic resistance genes, which were mostly trimethoprim genes (7 isolates, 2.9%). All strains were positive for LIPI-1, and only a part of strains harbored LIPI-3 and LIPI-4, accounting for 13.8% (33 isolates) and 14.2% (34 isolates), respectively. ST619 carried both LIPI-3 and LIPI-4. 51.5% (123 isolates) of strains carried SSI-1, and all CC121 strains harbored SSI-2. Different lineages, serogroups and CCs can be separated obviously through cgMLST analysis, and 24 sublineages were highly concordant with CCs. Conclusion: Ⅱa was the main serogroups in ready-to-eat food isolates in China; CC8, CC101 and CC87 were the prevalent CCs, and CC87 isolates was hypervirulent isolates, cgMLST method can be adopted for prospective foodborne disease surveillance and outbreaks detection.

Listeria monocytogenes is a facultative, intracellular foodborne pathogen that causes listeriosis and is prevalent worldwide. However, our knowledge of this bacterium and the listeriosis it causes is still extremely limited until now. Therefore, this retrospective study of patients in mainland China over 10 years (2008-2017) was performed to better understand the demographic trends and clinical features of listeriosis in China. Both electronic and manual retrieval systems were used to collect the relevant literature on listeriosis in mainland China. A total of 759 cases were reported from 22 provinces. Among the clinical cases, septicemia was the most common presentation (49%), followed by central nervous system infection (25%). The overall case fatality rate was 18%, with a higher rate among neonatal patients (73%). In recent years, listeriosis has been reported annually and even peaked in 2014. The median age of nonperinatal cases was 36 years (range, 0-102), with a predominance of male cases (52%). Sporadic cases were frequent from March to May. Efforts to prevent and control the spread of listeriosis are required through further research and collaborative efforts to improve the capacities of clinical diagnosis and treatment.

Meat products are commonly regarded as one of the main sources of human listeriosis caused by Listeria monocytogenes. The objective of this study was to estimate the prevalence of L. monocytogenes in a range of meat products from 24 different Chinese regions by using meta-analysis of literature data and a novel sensitivity analysis approach. A total of 112 publications from five databases, published between 1 January 2007 and 31 December 2017, were systematically selected for relevance and covered meat products sampled between 2000 and 2016. Estimated by the random-effects model, the pooled prevalence of L. monocytogenes was 8.5% (95% CI: 7.1%-10.3%) in raw meats and 3.2% (95% CI: 2.7%-3.9%) in ready-to-eat (RTE) meats. The prevalence differed from high to low among raw meats including prefabricated raw meats 12.6% (95% CI: 6.9%-21.7%), fresh pork 11.4% (95% CI: 8.6%-14.9%), fresh beef 9.1% (95% CI: 6.3%-13.0%), fresh poultry 7.2% (95% CI:4.9%-10.4%), frozen raw meats 7.2% (95% CI: 5.7%-9.0%), and fresh mutton 5.4% (95% CI: 2.5%-11.0%). A higher L. monocytogenes prevalence level was shown in the meat products from central and northeastern China provincial regions. The entropy-based sensitivity analysis utilized in the meta-analysis indicated that the sampling period and location were two critical factors influencing the prevalence level of L. monocytogenes in meat products. A better understanding of differences in prevalence levels per geographic region and between meat product sources may allow the competent authorities, industry, and other relevant stakeholders to tailor their interventions to control the occurrence of L. monocytogenes in meat products effectively., (Copyright © 2019 Elsevier B.V. All rights reserved.)

During 2013-2017, a total of 211 cases of listeriosis were reported by 64 sentinel hospitals in China to a national foodborne disease surveillance network. The average case-fatality rate was 31.2% for perinatal cases and 16.4% for nonperinatal cases. Sequence types 87 and 8 were the most prevalent types.

Objective: The aim of this study was to conduct a systematic review to better understand the epidemiological and clinical characteristics of listeriosis patients in mainland China., Methods: The six most widely used Chinese and English language databases were searched. The records of patients with listeriosis in mainland China reported during the years 2011-2017 were extracted. The clinical data of patients and information on clinical isolates of Listeria were collected and analyzed., Results: In total, 136 records were identified, reporting 562 patients with listeriosis. The number of patients was much higher than that reported in the previous decade. The 227 non-perinatal listeriosis patients included had a mortality rate of 23.78%. Of the 231 perinatal listeriosis patients, 32.68% resulted in abortion and/or newborn death. All listeriosis cases were reported as being sporadic. The listeriosis was traced to infection via a meat product in only three patients, while 33.12% were healthcare-associated infections., Conclusions: The number of patients with listeriosis in mainland China may have been underestimated previously. Perinatal cases in mainland China account for a much higher proportion than is usually described. Considering the high number of listeriosis patients in China, a comprehensive monitoring system for Listeria is urgently needed., (Copyright © 2019 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: To estimate the public health risk related to cooked meat in bulk products contaminated with Listeria monocytogenes, a generic Bayesian network (BN) risk-assessment model was developed to simulate influencing factors and processes of products from the industry level to the consumer level. To quantify the model, parameter values of prior distributions were acquired from the literature, websites, and expert opinions. Using the Markov chain Monte Carlo (MCMC) simulation approach, posterior probability distributions were calculated according to the incorporated evidence, which allowed us to predict various risks affected by processing variability from production to consumption., Results: The average risks of listeriosis from consuming cooked meat in bulk products are 8.40 × 10 -7 , 2.58 × 10 -8 , 8.24 × 10 -7 , and 1.05 × 10 -6 per meal for children, young people, elderly people, and pregnant women, respectively. The estimated mean number of listeriosis cases is 5 per 100 000 people per year in China., Conclusion: Although only a conceptual BN model is given, it manifests the principles and characteristics of mathematical methods. The BN model can also provide significant benefits for quantitative risk assessment by incorporating all available data and by updating beliefs. © 2018 Society of Chemical Industry., (© 2018 Society of Chemical Industry.)

Listeria monocytogenes, a ubiquitous bacterium in nature, can lead to human listeriosis through food consumption. Listeriosis is a rare, preventable, and treatable foodborne disease but can cause hospitalizations and fatalities. We reviewed the literature published in China to better understand the prevalence of L. monocytogenes in food products, incidence of human listeriosis, and characteristics of L. monocytogenes strains in China. The average prevalence of L. monocytogenes in Chinese food products in 28 provinces was 4.42%, with the highest prevalence of 8.91% in meat-poultry products, followed by aquatic animals, Chinese salad and salad, rice and flour products, and so on. Two hundred fifty-three invasive listeriosis cases were reported from 2011 to 2016 in 19 provinces, and the overall case-fatality rate was 25.7% with no deaths reported of pregnant women and children. L. monocytogenes strains were generally susceptible to most antibiotics, with ampicillin and penicillin G still effective in treatment. The predominant sequence types (STs) in food were ST9 and ST8, while clinically ST87 was most common ST in China. The national human listeriosis pilot surveillance started in 2013, and a total of 133 listeriosis cases have been collected until now. On the basis of the surveillance program, further research should be conducted to uncover the reason for the prevalence and pathogenic mechanism of the highly epidemiological hypervirulent ST87 strains in China.

Listeria monocytogenes is capable of infecting almost all animals. However, outbreaks of listeriosis are infrequent in birds. This report describes an outbreak of listeriosis in a small pheasant (Phasianus colchicus) breeder farm with more than 2,000 pheasants from Hubei province of the People's Republic of China. The affected flock consisted of adult and young birds. Approximately 300 young birds and a few adult birds were found dead within a few days of the onset of clinical signs. Twenty-five dead birds were collected for further examination. Histopathological lesions in the visceral organs were characterized by monocyte infiltration and proliferation. Localized encephalitis and meningitis were detected in the brains of dead birds. Gram-positive organisms were observed in heart blood smear, liver, and brain impression smears. The organisms were isolated from fresh liver and were identified as L. monocytogenes serotype 4b based on multiplex polymerase chain reaction (PCR) and hlyA gene sequence analysis. This is the first report describing outbreak of listeriosis in pheasant flock., (© 2015 Poultry Science Association Inc.)

Listeria monocytogenes is an important foodborne pathogen of public health concern. A total of 902 retail food samples, including 342 ready-to-eat (RTE) foods, 366 infant foods, and 194 raw chickens were collected randomly in supermarkets and farmers' markets in 12 geographic areas in Shaanxi Province, China and screened for L. monocytogenes. All L. monocytogenes isolates were characterized by antimicrobial susceptibility testing, serotyping, and pulsed-field gel electrophoresis (PFGE). Twenty-seven (3.0%) samples were positive for L. monocytogenes, and 39 L. monocytogenes isolates were recovered from positive samples. Of these L. monocytogenes isolates, 21 isolates (53.8%) showed resistance to at least one antimicrobial. The isolates displayed resistance most frequently to oxacillin (18 isolates, 46.2%), followed by tetracycline (five isolates, 12.8%), erythromycin (four isolates, 10.3%), trimethoprim/sulfamethoxazole (three isolates, 7.7%), chloramphenicol (two isolates, 5.1%), and vancomycin (one isolate, 2.6%). All isolates were sensitive or displayed intermediate resistance to gentamicin, ampicillin, ciprofloxacin, and amikacin. Four serotypes including serotype 1/2b, 4b, 4e, and 1/2a were identified in those foodborne isolates. PFGE analysis demonstrated that some isolates with the same PFGE patterns came from different food sources, and isolates from the same food source tend to cluster closely. Presence of L. monocytogenes of clinically important serotypes in retail foods and their antimicrobial resistance constitute a potential risk for the public. Appropriate measures should be taken by government, industry, and consumers to reduce the risk posed by this ubiquitous pathogen.

Background: Listeriosis is an emerging infectious disease associated with high mortality. There are few published reports from East Asia and developing countries. Our goal was to describe the clinical characteristics and outcomes of patients diagnosed with Listeria monocytogenes at a tertiary care hospital in Beijing, China., Methods: Peking Union Medical College Hospital (PUMCH), an 1800-bed hospital, consists of 2 campuses that house different medical departments. We retrospectively reviewed all culture-proven cases of listeriosis occurring at PUMCH between 1999 and 2011. Point estimates and 95% confidence intervals are presented., Results: There were 38 patients with listeriosis: 5 neonatal, 8 maternal, and 25 nonmaternal. The median age of the adult nonmaternal patients was 47 (range, 18-79) years with a female predominance (72%). Forty percent (n = 10) had an underlying rheumatic disease. Forty-four percent of cases (n = 11) were healthcare-associated infections occurring a median of 20 (range, 3-44) days after hospital admission. Only 2 of the 11 healthcare-associated cases clustered in space and time. One healthcare-associated case occurred in a patient receiving KHI-272 therapy, an oral, irreversible dual EGFR/HER2 inhibitor. The neonatal and maternal listeriosis cases were similar to those reported in the literature., Conclusions: Nonclustered healthcare-associated cases of L. monocytogenes occurred at a large tertiary care hospital in Beijing, China. The source of these infections is unclear. Although rare, in the setting of immunosuppression, Listeria should be considered in the differential diagnosis of healthcare-associated infections, even in the absence of a point-source outbreak.

Background: Listeria monocytogenes can cause invasive diseases in humans and farm animals and is frequently isolated from dairy products and poultry. Listeriosis is uncommon in China but L. monocytogenes has been isolated from foods and food processing environments in China. However little is known of genetic diversity of Chinese L. monocytogenes isolates and their relationships with global isolates., Results: Two hundred and twelve isolates of L. monocytogenes from food sources from 12 provinces/cities in China were analysed by serotyping, Pulsed Field Gel Electrophoresis (PFGE) and Multi-locus Sequence Typing (MLST). The predominant serotypes are 1/2a, 1/2b and 1/2c accounting for 90.1% of the isolates. PFGE divided the isolates into 61 pulse types (PTs). Twenty nine PTs were represented by more than one isolates with PT GX6A16.0004 containing the most number of isolates. MLST differentiated the isolates into 36 STs, among which 15 were novel. The 3 most common STs were ST9 (29.1%), ST8 (10.7%) and ST87 (9.2%), accounting for 49.0% of the isolates., Conclusions: STs prevalent in other parts of the world are also prevalent in China including 7 STs (ST1-ST3, ST5, ST6, ST8, ST9) which caused maternal fetal infections or outbreaks, suggesting that these STs potentially can also cause severe human infections or outbreaks in China. Surveillance of these STs will provide important information for prevention of listeriosis. This study also enhances our understanding of genetic diversity of L. monocytogenes in China.

Unlabelled: A total of 48 Listeria monocytogenes isolates of different import food products from 8 provinces between 2005 and 2008 were characterized. The serotype and virulence were confirmed for each strain and molecular subtyping were analyzed by multilocus sequence typing (MLST). Twenty five strains were assigned to serotype 1/2a, and 11 isolates to serotype 1/2b, serotype 4b were found in 7 isolate, and the remaining 5 strains were grouped into serotypes 1/2c, 4a, and 4e. Molecular subtyping schemes found thirty two sequence types (STs) among these isolates and the majority of L. monocytogenes strains belonged to lineage II (56%), followed by lineage I (38%), lineage III (6%). Two molecular subtype clusters, cluster A included all isolates of lineage II, while cluster B contained the isolates of lineages I and lineages III. Two L. monocytogenes strains were not grouped in either of the two clusters. Fifty three isolates were as virulent as L. monocytogenes reference strain EGD in mouse virulence assay, while the isolates 22213 and 22265 had low pathogenicity. These results provide the first molecular insight into the L. monocytogenes strains isolated from import food products of 8 provinces in China and indicate the potential risk to cause human disease if intake by contaminated foods. MLST could be used as a routine subtyping method of L. monocytogenes isolates. In China, inspection and quarantine strategies of imported foods should be strengthened., Practical Application: There is a potential risk of listeriosis in China and routine subtyping of L. monocytogenes isolates is important. It is necessary for food hygiene management to strengthen the supervision of imported foods., (© 2012 Institute of Food Technologists®)

Background: Listeria monocytogenes infection is not commonly reported in China. Increasing the awareness of neonatal listeriosis is necessary., Methods: Six cases of neonatal listeriosis were diagnosed in the neonatal intensive care unit at Beijing Obstetrics & Gynecology Hospital in 2008. We reviewed the clinical features, laboratory findings, timing of treatment, medications used, and the history of the mothers during pregnancy., Results: All six cases were preterm infants. Blood cultures were positive for L. monocytogenes. All of the mothers developed fever in the third trimester of pregnancy, and three of them ended their pregnancy the day the fever appeared. The severity of the clinical symptoms varied in each infant, and all cases were treated with antibiotics immediately after birth. All six cases were discharged from hospital in good health., Conclusions: Neonatal Listeria infection is generally a severe disease. Pregnant women must guard against fever and other manifestations, such as Listeria infection. Clinicians encountering such cases should be attentive to the patient's condition and should provide appropriate antibiotic treatment. Early detection and effective targeted treatment of listeriosis helps to improve the patient's survival and prognosis., (© 2011 The Authors. Pediatrics International © 2011 Japan Pediatric Society.)

Objective: To study the virulent gene prevalence of foodborne Listeria monocytogenes (LM) isolated from China., Methods: 78 LM isolates derived from raw meat, cooked food, aquatic products and vegetables of 13 provinces and cities.LM isolates were investigated for prevalence of virulence genes (LIPI-1 (prfA, plcA, hly, mpl, actA, plcB); LIPI-2 (inlA, inlB), and iap) by PCR method., Results: 87.2% (68/78) of the isolates were prfA positive, 98.7% (77/78) of the isolates were plcA, actA and plcB positive, 97.4% (76/78) of the isolates were hly positive, 87.2% (68/78) of the isolates were mpl positive, 92.3% (72/78) of the isolates were inlA positive, 100% (78/78) of the isolates were inlB positive, 98.7% (77/78) of the isolates were iap positive. Among 21 virulent gene negative isolates, there was 7 isolates lack of two or more virulence genes. The rate of virulence genes deletion isolates from cooked meat was 31.3% (10/32), the rate of virulence genes deletion isolates from raw meat was 16.1% (5/31), the rate of virulence genes deletion isolates from vegetables was 36.4% (4/11) and rate of virulence genes deletion isolates from seafood was 50% (2/4). No significant difference was found (χ(2) = 3.721, P > 0.05). The virulence gene array-1 strains were dominant among these isolates., Conclusion: Among 78 LM isolates, prevalent of virulent genes were different except inlB, virulence genes of LIP-1 were deleted prevalently among isolates, virulence gene deletion patterns were diverse.

Objective: We examined the prevalence, molecular characteristics and virulence potential of Listeria monocytogenes isolates from imported fishery products to gain further insights on the public health risk caused by this important food borne pathogen., Methods: L. monocytogenes isolates, screened from 1275 batches of fishery products imported from July 2007 to November 2008, were studied by lineage classification, serotyping, in vivo virulence assessment in ICR mouse model and multilocus sequence typing (MLST)., Results: Thirty-three batches were contaminated by L. monocytogenes (33/1275, 2.6%), in which serovar 4b dominated (65.2%), followed by serovars 1/2b (17.4%), 1/2a (13.0%) and 1/2c (4.4%). These isolates were all as virulent as L. monocytogenes reference strains. Of 23 selected L. monocytogenes isolates and 9 reference strains, 23 sequence types (STs) were recognized with discrimination index (D.I.) of 0.97, based on the concatenated gene cluster covering one virulent gene actA, two housekeeping genes hisJ and ribC, and one stress-response gene sigB. Remarkably, 3 isolates from American salmon, Argentina squid and Peru squid respectively belonged to ST9 which represented epidemic clone I (ECI). The isolation rate of L. monocytogenes in imported fishery products (2.6%) was similar to that in domestic fishery products (2.7%). Serovar 4b, which was more virulent than other serovars in humans, was dominant in imported fishery products, and even ECI was recognized., Conclusion: All of these isolates were as virulent as L. monocytogenes reference strains, suggesting inspection and quarantine strategies of imported fishery products should be strengthened effectively.