Pregnancy-associated listeriosis in England and Wales

Lysteria Monocytogenes Infection during Monochorionic Twin Pregnancy: Case Report and Review of the Literature

Listeriosis is a rare but severe foodborne disease caused by Listeria Monocytogenes (LM), a small facultative intracellular bacillus. When occurring in pregnant women, it can be vertically transmitted to the fetus and the newborn. Infected women usually display aspecific and mild symptoms, and rarely develop the severe forms of the disease (such as neurolisteriosis). On the contrary, fetal and neonatal listeriosis can lead to complications such as fetal loss, preterm birth, neonatal sepsis, and respiratory distress syndrome (RDS). Prompt diagnosis is one of the main challenges because of the aspecific presentation of the disease; therapy relies on antibiotics that reach high intracellular concentration and can penetrate and pass the placenta reaching the fetus. Herein we report an infrequent case of LM infection involving a woman with monochorionic diamniotic twin pregnancy, followed by a comprehensive review of the available literature on listeriosis in pregnancy.

Comparative seropositivity of Listeria monocytogenes in the serum of pregnant women with and without a history of abortion by serological and culture methods

Objective

Listeria monocytogenes is a major cause of miscarriage and postpartum infections in infant. Determining antibody levels against listeriolysin O can be valuable for diagnosing both invasive listeriosis and febrile gastroenteritis. However, serological methods that detect antibodies against incomplete forms of listeriolysin O can be more specific. The objective of this study was to identify (Listeria monocytogenes) in the serum of pregnant women using serological and culture methods.

Methods

Clinical samples (120 cases) were collected from pregnant women with a gestational age of less than 20 weeks. Diagnosis of Listeria monocytogenes was conducted using culture methods to identify anti-Listeria antibodies. Statistical analysis of the results was conducted using IBM SPSS Statistics version 23.0 (New York, USA), Pearson's Chi Square and fisher tests.

Results

The number of positive samples by culture and ELISA was 24.16% (29) and 28.3% (34), respectively. Out of the 29 positive sample by the culture method, 10 individuals had no abortion history, 16 and 3 individuals had 1 and 2 abortions and no sample had 3 abortions. Maybe, the more abortions a person has had, the less likely they are to be infected. In the Enzyme Linked Immuno-Sorbent Assay (ELISA) method, 13 individuals tested positive for both IgG and IgM antibodies and 38 individuals tested negative. Additionally, among the positive individuals with 1, 2, and 3 miscarriages, 0, 17, and 3 people were positive for the IgG antibody and 0, 18, and 3 individuals were positive for the IgM antibody. The analysis results indicated that there was no significant relationship between culture and abortion history (p = 0.316), IgG ELISA and history of miscarriage (p = 0.672) and IgM ELISA and history of miscarriage (p = 0.552).

Conclusion

There was no significant relationship between infection with Listeria monocytogenes and abortion (p ⩾ 0.05) in our samples. These results should be interpreted with caution due to the limitation of our small sample size.

Adherence to the national guidance on foods and drinks to limit or avoid during pregnancy in England: the PEAR Study

OBJECTIVE

The National Health Service (NHS) England website provides guidance on foods/drinks to avoid or limit during pregnancy because of microbiological, toxicological or teratogenic hazards. The aims were to determine adherence and whether demographic characteristics were associated with adherence.

DESIGN

Cross-sectional study.

SETTING

Online survey of postpartum women resident in England during pregnancy.

PARTICIPANTS

Recently, postpartum women resident in England during their pregnancy (n 598; median age 33 (IQR 30-36) years) completed an online questionnaire (April-November 2022). Questions included those on consumption of twenty-one food/drink items that the NHS advises pregnant women to avoid/limit. The study is part of the Pregnancy, the Environment And nutRition (PEAR) Study. Summary statistics were used to determine proportions adhering to the guidance. Adjusted logistic regression was used to model the associations of adherence with demographic characteristics.

RESULTS

Adherence was generally high (>90 % for eight of ten food/drink items to be avoided). However, among pre-pregnancy consumers, several items were not completely avoided, for example, 81 % (128/158) for game meat/gamebirds, 37 % (176/478) for cured meats and 17 % (81/467) for soft cheeses. Greater educational attainment (e.g. caffeinated soft drinks OR 2·25 (95 % CI 1·28, 3·94)), greater maternal age (e.g. oily fish 1·64 (1·05, 2·56)) and lower parity (e.g. caffeinated coffee 0.28 (0.11, 0.69)) were the most usual characteristics associated with adherence.

CONCLUSION

Evidence of concerning levels of non-adherence for some food/drink items suggests a case for more education on some of the guidance, particularly for women with lower educational attainment, greater parity and greater maternal age. Further research on barriers to the implementation of the guidance is needed.

Genomic epidemiology of the clinically dominant clonal complex 1 in the Listeria monocytogenes population in the UK

Listeria monocytogenes is a food-borne pathogen, typically affecting the elderly, immunocompromised patients and pregnant women. The aim of this study was to determine the population structure of L. monocytogenes clonal complex 1 (CC1) in the UK and describe the genomic epidemiology of this clinically significant CC. We interrogated a working dataset of 4073 sequences of L. monocytogenes isolated between January 2015 and December 2020 from human clinical specimens, food and/or food-production environments. A minimum spanning tree was reconstructed to determine the population structure of L. monocytogenes in the UK. Subsequent analysis focused on L. monocytogenes CC1, as the cause of the highest proportion of invasive listeriosis in humans. Sequencing data was integrated with metadata on food and environmental isolates, and information from patient questionnaires, including age, sex and clinical outcomes. All isolates either belonged to lineage I (n=1299/4073, 32%) or lineage II (n=2774/4073, 68%), with clinical isolates from human cases more likely to belong to lineage I (n=546/928, 59%) and food isolates more likely to belong to lineage II (n=2352/3067, 77%). Of the four largest CCs, CC1 (n=237) had the highest proportion of isolates from human cases of disease (CC1 n=160/237, 67.5 %; CC121 n=13/843, 2 %; CC9 n=53/360, 15 %; CC2 n=69/339, 20%). Within CC1, most cases were female (n=95/160, 59%, P=0.01771) and the highest proportion of cases were in people >60 years old (39/95, 41%, P=1.314×10-6) with a high number of them aged 20-39 years old (n=35/95, 37%) most linked to pregnancy-related listeriosis (n=29/35, 83%). Most of the male cases were in men aged over 60 years old (40/65, 62%), and most of the fatal cases in both males and females were identified in this age group (42/55, 76%). Phylogenetic analysis revealed 23 5 SNP single linkage clusters comprising 80/237 (34 %) isolates with cluster sizes ranging from 2 to 19. Five 5 SNP clusters comprised isolates from human cases and an implicated food item. Expanding the analysis to 25 SNP single linkage clusters resolved an additional two clusters linking human cases to a potential food vehicle. Analysis of demographic and clinical outcome data identified CC1 as a clinically significant cause of invasive listeriosis in the elderly population and in women of child-bearing age. Phylogenetic analysis revealed the population structure of CC1 in the UK comprised small, sparsely populated genomic clusters. Only clusters containing isolates from an implicated food vehicle, or food processing or farming environments, were resolved, emphasizing the need for clinical, food and animal-health agencies to share sequencing data in real time, and the importance of a One Health approach to public-health surveillance of listeriosis.

Clinical Features and Antibiotic Treatment of Neonatal Listeriosis: A Hospital-Based Study

Purpose

To determine the clinical features, laboratory findings, antibiotic treatment, and outcomes of neonatal listeriosis in a specialized tertiary hospital in Wuhan, China.

Patients and Methods

We retrospectively analyzed the medical records of patients diagnosed with neonatal listeriosis at Maternal and Child Health Hospital of Hubei Province from January 2015 to December 2022. Listeriosis was indicated by positive culture for Listeria monocytogenes (LM).

Results

A total of 11 cases were included in our study. The incidence rate of neonatal listeriosis was 2.06 per 100,000 live births. Seventy-three percent of the cases were born prematurely, caused early onset sepsis. Respiratory distress (100%) was the most common and earliest symptom, followed by fever (64%) and rashes (27%). The levels of C-reactive protein (CRP) and procalcitonin (PCT) were elevated in 100% of the cases. The median time-to-positivity (TTP) of the culture was 15 hours (range 9-28hours). Of the 11 neonates, 6 were cured, 2 showed improvement, and 3 died, with a mortality rate of 27%. There were statistically significant differences in Apgar score at 5 minutes (p=0.037) and CRP (p=0.025) between the survival group and fatality group. Ampicillin was sensitive to LM isolates and effective for therapy if initiated early.

Conclusion

Neonatal listeriosis is a rare but severe infection with a high mortality rate. Early identification and appropriate use of effective antibiotics are particularly critical for achieving positive outcomes. Apgar score and CRP are relevant indices for prognosis. Ampicillin is the first-line therapy and can be empirically administered to neonates suspected of having listeriosis.

Provision of information by midwives for pregnant women in England on guidance on foods/drinks to avoid or limit

BACKGROUND

The National Health Service (NHS) website gives guidance for pregnant women in England on foods/drinks to avoid or limit because of microbiological, toxicological or teratogenic hazards. These include, for example, some types of soft cheeses, fish/seafood and meat products. This website and midwives are trusted sources of information for pregnant women, but the ways in which midwives can be supported to provide clear and accurate information are unknown.

AIMS

The aims were to: (1) determine midwives' accuracy of recall of information and confidence in delivering the guidance to women; (2) identify barriers to provision; (3) identify the ways in which midwives provide this information to women.

METHODS

Registered Midwives practicing in England completed an online questionnaire. Questions included those on what information they provided and their confidence in delivering it, the ways they provided information on foods to avoid/limit, their recall of some of the guidance, and what resources they used. Ethics approval was given by the University of Bristol.

RESULTS

More than 10% of midwives (n = 122) were 'Not at all confident/Don't know' in providing advice about ten items, including game meat/gamebirds (42% and 43%, respectively), herbal teas (14%) and cured meats (12%). Only 32% correctly recalled overall advice on eating fish, and only 38% the advice on tinned tuna. The main barriers to provision were lack of time in appointments and lack of training. The most usual methods of disseminating information were verbal (79%) and signposting to websites (55%).

CONCLUSION

Midwives were often unconfident about their ability to provide accurate guidance, and recall on items tested was frequently mistaken. Delivery of guidance by midwives on foods to avoid or limit needs to be supported by appropriate training and access to resources, and sufficient time in appointments. Further research on barriers to the delivery and implementation of the NHS guidance is needed.

Maternal bacteremia caused by Listeria monocytogenes ST87: A case report

Pregnant women are at a high risk of contracting listeriosis; however, there have been only a few clinical reports of maternal bacteremia occurring before 20 weeks of gestation in China. In this case report, a 28-year-old pregnant woman at 16 weeks and 4 days of gestation was admitted to our hospital suffering from fever for four days. The patient was initially diagnosed with an upper respiratory tract infection at the local community hospital; nevertheless, the cause of the infection was unknown. In our hospital, she was diagnosed with Listeria monocytogenes (L. monocytogenes) infection by the blood culture system. Before the results of blood culture were obtained, ceftriaxone and cefazolin were given for three days respectively based on clinical experience. However, the fever didn't reduce until she was treated with ampicillin. This pathogen was further identified as L. monocytogenes ST87 by serotyping, multilocus sequence typing (MLST), and virulence gene amplification. Finally, a healthy baby boy was born in our hospital, and the neonate was developing well at the 6-week postnatal follow-up visit. This case report suggests that patients with L. monocytogenes ST87-caused maternal listeriosis can have a good prognosis; however, more clinical information and molecular experiments are needed to confirm our hypothesis.

Patterns of enteric infections in a population-wide cohort study of sequelae, British Columbia, Canada

We assessed patterns of enteric infections caused by 14 pathogens, in a longitudinal cohort study of sequelae in British Columbia (BC) Canada, 2005-2014. Our population cohort of 5.8 million individuals was followed for an average of 7.5 years/person; during this time, 40 523 individuals experienced 42 308 incident laboratory-confirmed, provincially reported enteric infections (96.4 incident infections per 100 000 person-years). Most individuals (38 882/40 523; 96%) had only one, but 4% had multiple concurrent infections or more than one infection across the study. Among individuals with more than one infection, the pathogens and combinations occurring most frequently per individual matched the pathogens occurring most frequently in the BC population. An additional 298 557 new fee-for-service physician visits and hospitalisations for enteric infections, that did not coincide with a reported enteric infection, also occurred, and some may be potentially unreported enteric infections. Our findings demonstrate that sequelae risk analyses should explore the possible impacts of multiple infections, and that estimating risk for individuals who may have had a potentially unreported enteric infection is warranted.

Maternal and obstetric outcomes of listeria pregnancy: insights from a national cohort

OBJECTIVE

We sought to evaluate and describe the maternal and obstetric morbidity associated with Listeria infection in pregnancy.

METHODS

Retrospective cohort of pregnant women using the 2007-2018 National Inpatient Sample. Pregnant women with discharge diagnosis codes consistent with Listeria infection were identified. Outcomes of deliveries complicated by Listeria infection were compared to those of delivery without this infection. The primary outcome was a composite of severe maternal morbidity. Secondary outcomes included components of the composite, maternal length of stay, mode of delivery, stillbirth, and preterm delivery.

RESULTS

We identified 134 maternity associated hospitalizations for Listeria (weighted national estimate 666), of which 72 (weighted national estimate of 358) were delivery admissions. Delivery admissions complicated by Listeria resulted in higher rates of severe maternal morbidity than those without, (30.9% vs. 1.6%, p<.001). In adjusted analyses, women with Listeria had 21.2-fold higher risk of severe maternal morbidity (95% CI: 14.0, 31.9) when compared to those without Listeria. Specifically, Listeria delivery admissions had higher rates of acute respiratory distress syndrome (2.8% vs. 0.1%, p<.001), mechanical ventilation (1.4% vs. 0.0%, p<.001), sepsis (28.1% vs. 0.1%, p<.001), and shock (1.4% vs. 0.0%, p<.001). Listeria delivery admissions also had higher rates of preterm birth (61.3% vs. 7.7%, p < 0.001) and stillbirth (13.5% vs. 0.7%, p<.001). Women hospitalized or delivered with Listeria infection were also more likely to have a cesarean delivery (57.9% vs. 32.9, p<.001) and the average length of stay for women with Listeria was also longer (4.0 days vs. 2.3 days, p<.001).

CONCLUSIONS

Women with Listeria infection in pregnancy have higher rates of severe maternal morbidity, specifically increased risk of sepsis, septic shock, and acute respiratory distress syndrome. Among delivery hospitalizations, these women also have higher rates of preterm birth and stillbirth.

Complications Associated with Foodborne Listeriosis: A Scoping Review

Listeria monocytogenes is a relatively rare but highly pathogenic bacterium that can cause foodborne infections. In the United States there are ∼1600 cases per year, 94% of which result in hospitalizations and 20% in deaths. Per-case burden is high because the disease also causes serious complications, including sepsis, encephalitis, meningitis, miscarriage, and stillbirth. The disease burden of L. monocytogenes is underestimated because some of these acute complications can also result in long-term outcomes. In this article, we conducted a scoping review of L. monocytogenes complications and longer term outcomes from articles published between 2000 and 2018. Search terms were developed for four major databases (PubMed, Scopus, Web of Science, and Embase) as well as gray literature and hand searches of review articles. We follow standard scoping review methodology and assessment. Out of 10,618 unique articles originally identified, 115 articles were included, representing 49 unique outcomes. The majority of studies were cohort designs (n = 67) and conducted in the United States or Europe (n = 98). Four major outcome groupings were death, neurological disorders, sepsis, and congenital infection. This study identifies substantial research on the common acute complications of L. monocytogenes and few long-term consequences of L. monocytogenes. We identify the need for additional studies to determine the longer term impacts of these acute complications.

Listeriosis in pregnancy: An umbrella review of maternal exposure, treatment and neonatal complications

BACKGROUND

Listeria monocytogenes is a commonly found organism in processed and prepared food and the disease of listeriosis is associated with a high morbidity and mortality. Compared with the general population, the risk of being diagnosed with listeriosis increases during pregnancy. Listeriosis can lead to miscarriage, spontaneous preterm labour and preterm birth, stillbirth and congenital neonatal infections.

OBJECTIVES

We conducted a universal review of listeriosis in pregnancy and in the newborn.

SEARCH STRATEGY

The EMBASE, PubMed, Cinahl and Web of Science databases were searched for systematic reviews indexed before 1 December 2020.

SELECTION CRITERIA

Any systematic reviews evaluating the prevalence, treatment, diagnosis and effects of listeriosis during pregnancy and up to 4 weeks postnatally were included.

DATA COLLECTION AND ANALYSIS

Eligibility assessment, data extraction and quality assessment by the Methodological Quality Assessment of Systematic Reviews (AMSTAR-2) were performed in duplicate.

MAIN RESULTS

We identified 397 citations of which nine systematic reviews comprising 330 studies and 487 patients' reviews were included. Most systematic reviews (seven of nine) were of moderate to high quality. Prevention in pregnant women was based on adherence to strict dietary recommendations, such as reheating leftovers until steamed and avoiding unpasteurised dairy products. Listeriosis infections were likely to occur in the third trimester (66%) rather than in the first trimester (3%) of pregnancy. Symptoms are mostly fever and other flu-like symptoms, such as fatigue. Diagnosis was primarily made by culture of the pathogen. Intravenous amoxicillin or ampicillin were first-line treatment.

CONCLUSIONS

Listeriosis, a rare but serious infectious disease in pregnancy, can cause devastating consequences for the fetus and newborn. Appropriate preventative treatment should be initiated during early pregnancy to avoid complications.

TWEETABLE ABSTRACT

Listeria is commonly found in processed and prepared food. Prevention is the best way to avoid listeriosis during pregnancy.

Septicemia Due to Listeria monocytogenes Infection: A Systematic Review and Meta-Analysis

Listeriosis is a rare bacterial infection associated with foodborne illness that can result in septicemia, a serious acute outcome. Sepsis is responsible for one in three deaths during hospitalization. The objective of this study was to conduct a systematic review and meta-analysis to estimate the proportion of Listeria monocytogenes infections resulting in septicemia. PubMed, Embase, Scopus, and Web of Science were searched from January 1, 2000, to April 1, 2018, for epidemiological studies that assessed studies focusing on L. monocytogenes infections with the outcome of septicemia. Articles in English, Spanish, and Portuguese using case-control, cohort, or outbreak studies reporting measures of association between L. monocytogenes and septicemia were included. Bias and heterogeneity were assessed using univariate meta-regression for region, sample size, study design, and report method. Nineteen articles were eligible for inclusion post-screening, the majority of which were conducted in Europe (n = 15); utilized a retrospective cohort design (n = 16); and collected data via routine or laboratory surveillance methods (n = 10). Prevalence of sepsis ranged from 4.2% to 100% among study populations of 6 to 1374 individuals. Overall, the proportion of listeriosis cases that developed sepsis was 46% (95% confidence interval [CI] 31.0-61.0%); for neonatal cases, 21.3% (95% CI 11.0-31.6%); and for maternal and neonatal cases, 18.8% (95% CI 10.7-26.8%). The heterogeneity was high for overall and group meta-analyses, but it could not be explained by the subanalyses for the overall proportion, whereas for neonatal, and neonatal and maternal cases combined, China had a significantly lower proportion than Europe and the United States. Septicemia following L. monocytogenes infection is a severe acute complication with 31-61% rate found overall; however, greater delineation of demographic data is needed to determine important risk factors. Future research should aim to address the gaps in knowledge in the long-term outcomes of sepsis from L. monocytogenes infection, and whether these outcomes differ from those due to other infections.

Listeria infection in young infants: results from a national surveillance study in the UK and Ireland

OBJECTIVES

To describe the epidemiology, age at infection, clinical characteristics and outcome of listeria infection in young infants to inform management and empiric antibiotic choice in young infants.

DESIGN

Prospective 2-year surveillance of Listeria monocytogenes infection in young infants detected through the British Paediatric Surveillance Unit 'orange card' system and triangulated with the public health laboratories.

SETTING

National population study (England, Wales, Scotland and the Ireland) PATIENTS: All infants under 90 days with proven or probable invasive listeriosis MAIN OUTCOME MEASURES: Incidence, mortality, age of infection, clinical characteristics and outcome RESULTS: During a 2-year period (2017-2019), 27 cases of listeriosis in infants <90 days of age were reported. The incidence of listeriosis in this study was 1.8 per 100 000 live births with 7% mortality (2/27). Nearly all cases presented within the first 24 hours of life (26/27). The majority (20/27, 74%) were born preterm and 16/24 (67%) were born to women from ethnic minority backgrounds.

CONCLUSIONS

Invasive listeriosis in young infants in the UK and Ireland is rare and presents early in the neonatal period. National guidelines that recommend the use of amoxicillin as part of empiric regimes for sepsis and meningitis in infants over 1 month of age should be modified.

Seroprevalence of Listeria monocytogenes in HIV infected pregnant women from Brazil

Objective

To describe the prevalence and factors associated with serologic response to Listeria monocytogenes in HIV infected and uninfected pregnant women in Brazil.

Methods

Cross-sectional study, pregnant women after 14 weeks of gestational age were enrolled. Positive serologic test for L. monocytogenes was defined as titers >1:80 (agglutination test). Comparisons were performed using logistic regression.

Results

A total of 213 women were enrolled, 73 (34%) were HIV infected. 55 women were seroreactive for L. monocytogenes, 27 (37%) HIV-infected and 28 (20%) HIV-uninfected (p < 0.01). Considering the diet record, white cheese consumption was associated with seroreactivity (p < 0.01). In the group of pregnant women living with HIV, the variables associated with L. monocytogenes positive serology were: lower CD4+ cells count at study entry OR=4.8 (95%CI=1.1–19.8) and having neonates admitted to the intensive care unit OR=5.9 (95%CI=1.01–34.9).

Conclusion

Positive serology for Listeria monocytogenes was associated with HIV infection. Brazilian women should avoid white cheese during pregnancy.

Food Safety Knowledge and Practices of Pregnant Women and Postpartum Mothers in Slovenia

Food safety during pregnancy and postpartum is important for preventing foodborne diseases, while pregnant women are considered vulnerable due to their immunomodulatory condition. The current study aimed to investigate the self-reported food safety knowledge and practices of pregnant women and postpartum mothers in Slovenia using an online questionnaire and to compare the results with nonpregnant women as a control group. The study was conducted with 426 women, of whom 145 were pregnant, 191 were not pregnant, and 90 were postpartum. The online questionnaire consisted of questions related to food safety risk perception, hand hygiene, food purchase, food storage, food preparation and handling of infant formula and breast milk. The results showed that women generally have basic knowledge of proper food handling and are aware of food safety, but some specific gaps were identified in food handling at home, especially concerning microbiological risks. However, the results showed that pregnant women performed better than the postpartum group, and both groups performed significantly better than the nonpregnant group. The media was most frequently cited as a source of food safety information, especially by the pregnant group. Trained health workers should also inform women on how to ensure food safety in the home environment.

An 18-year retrospective study on the epidemiology of early-onset neonatal sepsis - emergence of uncommon pathogens

BACKGROUND

Nationwide group B Streptococcus agalactiae (GBS) antepartum screening was instituted in Taiwan in 2012. The impact of the policy on early-onset sepsis (EOS) has not been evaluated. This study aimed to examine the impact of the policy on the incidence of neonatal EOS.

METHODS

This was a retrospective study conducted at MacKay Children's Hospital. Patients with culture-proven neonatal EOS were enrolled and divided by birth year in relation to the implementation of GBS prevention policy: Epoch 1, 2001-2004 pre-GBS screening; Epoch 2, 2005-2011 elective GBS screening; and Epoch 3, 2012-2018 universal GBS screening. The pathogens and antimicrobial resistance patterns were reviewed and analyzed. The incidence was modeled using Poisson regression.

RESULTS

A total of 128 neonates met the enrollment criteria. The observed incidence of EOS was 1.52‰. The incidence rates of EOS, GBS, and Escherichia coli (E. coli) sepsis were similar in Epoch 1 and Epoch 3. E. coli and non-Enterococcal group D Streptococcus (GDS) infection increased significantly in term infants, whereas the EOS-related mortality rate declined in preterm infants. Approximately 72% of the isolated E. coli were ampicillin-resistant, and the antimicrobial sensitivity remained unaltered during the studied period.

CONCLUSIONS

The overall EOS incidence has not changed from 2001 to 2018. However, changes in the causative pathogens were observed in both term and preterm infants. Clinicians should be aware of this evolving epidemiology to provide prompt appropriate perinatal management.

An Update Review on Listeria Infection in Pregnancy

Listeria monocytogenes (LM) is an intracellular, aerobic and facultative anaerobic, Gram-positive bacterium, which is primarily transmitted to humans orally via food. LM could occur in asymptomatic pregnant women; however, fetal infection is a serious condition, entailing premature birth, abortion, sepsis, central nervous system (CNS) involvement, or even death. If a pregnant woman exhibits symptoms, the performance is almost like influenza, such as fever, headache, diarrhea, myalgia, or other digestive-related symptoms. This review collected clinical and empirical results regarding the mechanism, clinical manifestations, obstetrical outcome, diagnosis, treatment, vertical transmission, neonatal infection, and prevention of listeriosi according to articles published in PubMed from January 1, 1980, to March 20, 2021. The early detection and diagnosis of pregnancy-associated listeriosis are significant since sensitive antibiotics are effective at enhancing the prognosis of newborns. Listeriosis can be diagnosed using positive cultures from maternal or neonatal blood, neonatal cerebrospinal fluid (CSF), amniotic fluid, intrauterine mucosa, or the placenta. Two weeks of high-dose intravenous amoxicillin (more than 6 g/day) is recommended for LM pregnant women without allergy. Terminating the pregnancy to save the mother’s life should be considered if maternal and fetal conditions aggravate. Neonatal Listeria infection is primarily transmitted through the placenta, which is a critical illness associated with a high mortality rate. The necessary dietary guidance for pregnant women can reduce the incidence rate of pregnancy-related listeriosis.

Antimicrobial Susceptibility, Serotyping, and Molecular Characterization of Antibiotic Resistance Genes in Listeria monocytogenes Isolated from Pregnant Women with a History of Abortion

Background:

Listeria monocytogenes show high mortality among pregnant women and newborns. This study aimed to detect L. monocytogenes in pregnant women with a history of abortion and assess the serotypes, antibiotic susceptibility patterns, and its resistance genes.

Methods:

Overall, 400 vaginal swabs were taken from pregnant women with a history of abortion in the past few years in a tertiary care hospital in Tehran, Iran, during 2015–2018. Antibiotics susceptibility to a panel of 10 antibiotics was determined using the standard disk diffusion method and the isolates serotyped by the agglutination method. The antimicrobial-resistant isolates were also screened for the presence of tetM, ermB and dfrD genes by PCR.

Results:

Overall, 22 L. monocytogenes isolates were identified. High rates of resistance were observed for trimethoprim (50%; n=11), sulphamethoxazole (50%; n=11), tetracycline (45.45%; n=10) and gentamicin (36.36%; n=8). From 22 L. monocytogenes isolates, 13 (59.10 %), 5 (22.73%), 3 (13.63%) and 1 (4.54%) belonged to serotypes 4b, 1/2a, 1/2b, and 3c, respectively. The genetic determinant tetM was detected in 70% of the tetracycline-resistant isolates. Out of 11 trimethoprim-resistant isolates, 27.27% isolates contained dfrD. Moreover, the ermB gene was found in 83.33% of the erythromycin-resistant isolates.

Conclusion:

Ampicillin and partly penicillin consider to be suitable antimicrobial agents to treat human listeriosis. Moreover, due to resistance against many antibiotics, it is necessary to continue monitoring and managing antimicrobial resistance.

Determining the long-term health burden and risk of sequelae for 14 foodborne infections in British Columbia, Canada: protocol for a retrospective population-based cohort study

INTRODUCTION

Over one in eight Canadians is affected by a foodborne infection annually; however, the long-term consequences, including the risks and costs of sequelae, are unclear. We aim to estimate the health burden and direct costs of 14 infections commonly transmitted by food, considering the acute illness and subsequent sequelae and mortality, for the population of British Columbia, Canada (~4.7 million).

METHODS AND ANALYSIS

We will conduct a population-based retrospective cohort study of the British Columbia provincial population, over a 10-year study period (1 January 2005 to 31 December 2014). Exposure is defined as a provincially reported illness caused by Clostridium botulinum, Campylobacter, Cryptosporidium, Cyclospora, Giardia, hepatitis A virus, Listeria, non-typhoidal Salmonella spp, Salmonella Typhi, Salmonella Paratyphi, Shiga toxin-producing Escherichia coli, Shigella, Vibrio parahaemolyticus or Yersinia (excluding pestis). We will link individual-level longitudinal data from eight province-wide administrative health and reportable disease databases that include physician visits, hospitalisations and day surgeries, deaths, stillbirths, prescription medications (except those to treat HIV) and reportable foodborne diseases. Using these linked databases, we will investigate the likelihood of various sequelae and death. Hazard models will be used to estimate the risk of outcomes and their association with the type of foodborne infection. Epidemiological analyses will be conducted to determine the progression of illness and the fraction of sequelae attributable to specific foodborne infections. Economic analyses will assess the consequent direct healthcare costs.

ETHICS AND DISSEMINATION

This study has been approved by a University of Waterloo Research Ethics Committee (no 30645), the University of British Columbia Behavioral Research Ethics Board (no H16-00021) and McGill University's Institutional Review Board (no A03-M12-19A). Results will be disseminated via presentations to academics, public health practitioners and knowledge users, and publication in peer-reviewed journals. Where such publications are not open access, manuscripts will also be available via the University of Waterloo's Institutional Repository (https://uwspace.uwaterloo.ca).

Pregnancy Complicated by Listeria Monocytogenes: A Case Report and Review of the Literature

Listeria Monocytogenes, a small facultative anaerobic, gram positive, motile bacillus is a rare, but consequential etiologic agent of food borne illness which inordinately impacts immunocompromised individuals. The organism infects many types of animals and contaminates a multitude of foodstuffs such as milk, chicken, beef and vegetables. This microbe additionally has a distinct proclivity to infect the maternal-fetoplacental unit with resultant adverse perinatal outcomes inclusive of spontaneous abortion, preterm delivery, chorioamnionitis, neonatal meningitis and death. We present a case of Listeriosis complicating pregnancy with a subsequent comprehensive review of the literature.

An antenatal wish list: A qualitative systematic review and thematic synthesis of UK dietary advice for weight management and food borne illness

OBJECTIVES

To understand UK women's experiences of antenatal dietary advice for risk of food borne illness and weight gain.

DESIGN

A systematic review and thematic synthesis of peer-reviewed qualitative studies. PubMed, MEDLINE, CINAHL and PMC databases were searched for articles published from January 2008 to June 2018. The search strategy combined terms for pregnancy with terms for body composition, weight change, food safety, nutrition, diet and qualitative terminology. Studies were eligible for inclusion if (1) they explored experiences of implementing advice received during pregnancy for nutrition, physical activity and/or weight gain, and (2) participants were women who had experienced maternity care in the UK. Study quality was appraised using the Critical Appraisal Skills Programme (CASP) qualitative research appraisal tool.

FINDINGS

Of 25,688 articles identified by the search strategy, 20 studies were identified that met the inclusion criteria. Five major themes were recognised: control, barriers to diet and exercise, motivators, relationship with weight, and information, with a further 12 subthemes. The majority of studies reported on weight gain (n = 10).

KEY CONCLUSIONS

Evidence shows that UK antenatal dietary advice is currently inconsistent, vague and overwhelming despite pregnancy being an excellent time for lifestyle change. Women are primarily driven by the health of their baby and desire support to facilitate positive changes.

IMPLICATIONS FOR PRACTICE

Findings outline a wishlist which highlights a desire for tailored information on preventing weight gain, dietary requirements, safe physical activity and a deprioritisation of food safety guidelines. This provision should be delivered by HCP. e.g. midwives, in a sensitive and supportive way to bridge the gap between women's needs and the current antenatal provision.

Listeriosis in Pregnancy: A Review

Importance

Listeriosis is a rare foodborne condition that can cause serious health consequences in neonates and pregnant women. Listeria monocytogenes can be vertically transmitted to the fetus, resulting in adverse maternal, fetal, and neonatal outcomes. In this review, we summarize what is currently known about listeriosis in pregnancy and review the current management and treatment recommendations.

Objective

To summarize the clinical and relevant evidence available regarding listeriosis in pregnancy and educate providers on common clinical symptoms, sequelae, and appropriate treatment guidelines.

Evidence Acquisition

A PubMed review was conducted using search terms "pregnancy" OR "Listeria" OR "Maternal Listeriosis," and "Neonatal Listeriosis." The search included review articles, original research articles, and guidelines on diagnosis and management of listeriosis in pregnancy. The search was limited to the English language and publications between 1988 and July 2018.

Conclusions

Listeriosis in pregnancy can result in severe adverse maternal, fetal, and neonatal outcomes including miscarriage, preterm labor, fetal death, and neonatal meningitis and sepsis. Early treatment has been shown to improve fetal and neonatal outcomes; therefore, prevention with education and early diagnosis prompting treatment will improve overall outcomes.

Relevance

The incidence of listeriosis is expected to rise in the coming years due to changes in the US population, with increasing numbers of older Americans and Hispanic individuals, both of whom are at higher risk. Pregnant women contract listeriosis at a rate that is 16- to 18-fold greater than the general population. Given the expected increased rise in incidence and increased susceptibility of pregnant women, understanding the common clinical symptoms, maternal and fetal sequelae, and appropriate treatment guidelines is essential.

Challenging management of chorioamnionitis with placental listeriosis: lessons from 2 cases

Listeriosis is a rare foodborne infection caused by Listeria monocytogenes. It is 12–20 times more prevalent in pregnant women compared to the general population, with a 20–40% mortality rate in neonates. Early treatment with appropriate antimicrobial agents is critical for pregnancy outcomes; however, the infection is difficult to control because the nonspecific clinical manifestations and rarity of the disease often preclude early diagnosis. We encountered 2 cases of pregnancy-associated listeriosis that occurred at 29 and 37 weeks of gestation. Both neonates were delivered by emergent cesarean section due to fetal condition, and one of the preterm infants died immediately after birth. Pregnancy-associated listeriosis should be considered in the management of unexplained fever or inflammatory conditions in pregnant women.

Pregnancy-related listeriosis: frequency and genotypic characteristics of L. monocytogenes from human specimens in Kerman, Iran

Listeria monocytogenes is a foodborne pathogen that can pose serious complications during pregnancy and neonatal infection. This study aimed to determine the frequency of L. monocytogenes infection, prevalent serotypes, and virulence genes among pregnant women and those experiencing miscarriages in Kerman, Iran. Out of 200 vaginal swabs, 4.5 and 29.5% of specimens were positive for L. monocytogenes infection as identified by culture and molecular methods, respectively. The majority of isolates from positive cultures (89%) of pregnant women resulted in stillbirth, death, and blindness. The most prevalent virulence determinants were inl B, prf A, and act A. The majority of isolates were non-typable. A history of miscarriage and gestational age are known to be significantly associated with the presence of infection. This study emphasizes the importance of initial screening for L. monocytogenes in pregnant women in Iran. Molecular methods may be useful in this process. Increasing the awareness of pregnant women could be effective in reducing pregnancy-related listeriosis.

Epidemiological burden of Listeria monocytogenes in Iran

OBJECTIVES

Listeria monocytogenes is a foodborne pathogenic bacteria causing the infection listeriosis, which possibly affects all people, particularly immunocompromised persons and pregnant women. This microorganism can be found in several processed foods, dairy products, raw milk, meat and fish products, seafoods, eggs, fruits, and vegetables. This review discusses about the epidemiological significance, incidence, contamination routes of L. monocytogenes in different products and current data about listeriosis in the Iran.

MATERIALS AND METHODS

For accessing to relevant articles and studies, a search was done in main databases and also, almost all Iranian published articles were studied in this field.

RESULTS

Outbreaks of listeriosis have been reported in many parts of the worldwide, however there is scanty data about the prevalence of listeriosis in Iran. Accordingly, as a result of high incidence of L. monocytogenes in women with bad obstetric history or history of abortions, diagnosis procedures for detection of L. monocytogenes and timely treatment was suggested.

CONCLUSION

In spite of low incidence of infection in the past, increased interest for lightly preserved and/or ready-to-eat (RTE) food products has recently led to increasing of L. monocytogenes prevalence which has become a public health concern. Subsequently, further researches about the prevalence of L. monocytogenes and also antibiotic susceptibility testing is needed to enable the detection of the contaminated foods, as well as ensures the effective treatment.

Increasing Incidence of Listeriosis and Infection-associated Clinical Outcomes

BACKGROUND

Listeriosis caused by Listeria monocytogenes has a high case-fatality rate (CFR) of approximately 20% to 30%. An increasing incidence of listeriosis has been reported in many countries recently. We investigated the annual incidence, clinical characteristics, and outcomes of listeriosis at three different hospitals in Korea and evaluated the effects of appropriate empiric antimicrobial treatments on patient outcomes.

METHODS

We retrospectively collected the data of all culture-positive cases of human listeriosis from three hospitals of different sizes in Korea during 2006-2016 and calculated the annual number of cases and incidence per 100,000 admissions.

RESULTS

A total of 58 patients with L. monocytogenes were included in this study. The incidence of listeriosis was significantly higher in 2013-2016 than in 2006-2012 (RR 3.1; 95% CI 1.79-5.36; P<0.001), mainly because of an increase in patients over 60 years of age (RR 3.69; 95% CI 1.70-8.02; P<0.001). Multivariate analysis showed that healthcare-associated infection (adjusted OR, 12.15; 95% CI, 2.56-86.01; P=0.004) and empirical treatment with first-line antimicrobial agents (adjusted OR, 0.08; 95% CI, 0.00-0.63; P=0.044) were associated with CFR.

CONCLUSIONS

Healthcare-associated infections caused by L. monocytogenes are associated with high CFR. Adequate initial empirical treatments could reduce CFR, suggesting that careful consideration of an empirical antimicrobial regimen is warranted for elderly or immunocompromised patients admitted to the hospital.

Pregnancy-related listeriosis

About one in seven cases of listeriosis occurs in pregnant women, and, although listeriosis is rare, it is the third leading cause of death from food-borne infections. Pregnancy-related listeriosis increases the risk for fetal and neonatal mortality by approximately 21%. During pregnancy, infections are more likely to occur in the third trimester (66%) than the first trimester (3%). However, fetal and neonatal adverse effects are less common as gestational age increases or with older gestational age at birth. Pregnant women seem highly susceptible in some listeriosis outbreaks making up a large percentage of cases, whereas others contain very few. Whether this results from differences in strains of L. monocytogenes, exposures, or other factors remains to be determined. Food and Agriculture Organization of United Nations/World Health Organization (FAO/WHO) estimates the human lethal dose for 50% (LD₅₀ ) for fetal/neonatal loss is 1.9 × 10⁶ colony forming units (CFUs) L. monocytogenes. Animal models have been developed for pregnancy-related listeriosis showing similar susceptibility and clinical outcomes as in humans. Nonhuman primate and guinea pig animal models have similar (LD₅₀ ) values to the estimated human LD₅₀ . Additional animal studies are needed to understand the pathways leading to fetal and neonatal listeriosis in humans. More information is needed to understand dose response, to model risk for listeriosis at lower concentrations, and to determine why some pregnant women may be more susceptible than others. To better treat listeriosis during pregnancy, biomarkers for early diagnosis of listeriosis are also needed. Last, pregnant women need to be educated about avoiding high-risk foods, like Mexican-style cheese and ready-to-eat meats. Birth Defects Research 109:324-335, 2017.© 2017 Wiley Periodicals, Inc.

Listeria Placental Infection

The Gram-positive facultative intracellular bacterium Listeria monocytogenes is the causative agent of listeriosis, a severe food-borne infection. Pregnant women are at risk of contracting listeriosis, which can potentially lead to miscarriage, stillbirth, preterm birth, and congenital neonatal infections. While other systemic bacterial infections may result in adverse pregnancy outcomes at comparable frequencies, L. monocytogenes has particular notoriety because fetal complications largely occur in the absence of overt illness in the mother, delaying medical intervention. Here, we briefly review the pathophysiology and mechanisms of maternofetal listeriosis, discussed in light of a recent mBio report on Listeria transplacental infection in a nonhuman primate model.

Epidemiology and Molecular Typing of Pregnancy-Associated Listeriosis Cases in Lombardy, Italy, over a 10-Year Period (2005-2014)

In developed countries, pregnancy-related listeriosis accounts for 20–43% of total invasive listeriosis. This work describes the first pregnancy-related listeriosis survey in Italy based on two data sources, that is, mandatory notification system and regional laboratory-based network. Out of 610 listeriosis cases reported over a 10-year period, 40 were pregnancy-related (6.6%). Among these, 29 pregnancy-related isolates were available and have been analysed with serotyping, Pulsed-Field Gel Electrophoresis, and Multi-Virulence-Locus Sequence Typing. No maternal fatality was recorded, but 11 (29.7%) pregnancies resulted in a foetal death, a miscarriage, or a birth of a foetus dying immediately after birth. The average incidence of pregnancy-related listeriosis was 4.3 cases per 100000 births, and the proportion of pregnancy-associated listeriosis among ethnic minorities was significantly higher compared to the general population (30.0% versus 3.5%, P < 0.01). L. monocytogenes isolates belonged to serotypes 1/2a, 1/2b, and 4b, with the latter significantly more prevalent among pregnancy-related isolates. Twenty different pulsotypes were distinguished and 16 out of the 29 isolates were classified into seven clusters. A total of 16 virulence types (VTs) were identified. Five VTs accounted for 45% of the total cases and coincided with those of previously described Epidemic Clones (ECs) of L. monocytogenes.

Diversity of Listeria monocytogenes Strains of Clinical and Food Chain Origins in Belgium between 1985 and 2014

Listeriosis is a rare but severe disease, mainly caused by Listeria monocytogenes. This study shows the results of the laboratory-based surveillance of Listeriosis in Belgium over the period 1985-2014. Besides the incidence and some demographic data we present also more detailed microbiological and molecular characteristics of human strains isolated since 2000. The strains from the latter period were compared to food and animal strains from the same period. Our study shows that different food matrices were commonly contaminated with L. monocytogenes presenting the same PFGE profile as in patient's isolates. Since 1985, we observed a significant decrease in incidence of the Materno-Neonatal cases (from 0.15 to 0.04 cases /100,000 inhabitants-year), which is probably to be attributed to active prevention campaigns targeting pregnant women. Despite the strengthening of different control measures by the food industry, the incidence of non-Materno-Neonatal listeriosis increased in Belgium (from 0.3 to 0.7 cases /100,000 inhabitants-year), probably due to the rise of highly susceptible patients in an aging population. This significant increase found in non-Materno-Neonatal cases (slope coefficient 7.42%/year, P<0.0001) can be attributed to significant increase in incidence of isolates belonging to serovars 1/2a (n = 393, slope coefficient 6.62%/year, P<0.0001). Although resistance to antimicrobials is rare among L. monocytogenes isolates, a trend to increasing MIC values is evident with chloramphenicol, amoxicillin, tetracycline and ciprofloxacin. We show that fluoroquinolone resistance is not linked to chromosomal mutations, but caused by a variety of efflux pumps. Our study also shows that huge majority of known underlying pathologies (426 out of 785 cases) were cancers (185/426, 43.1%) and haematological malignancies (75/185, 40.5%). Moreover the risk population is susceptible to low levels of contamination in food stressing the need of prevention campaigns specifically targeting these persons.

Listeriosis and Toxoplasmosis in Pregnancy: Essentials for Healthcare Providers

Listeriosis and toxoplasmosis are foodborne illnesses that can have long-term consequences when contracted during pregnancy. Listeriosis is implicated in stillbirth, preterm labor, newborn sepsis, and meningitis, among other complications. Toxoplasmosis is associated with blindness, cognitive delays, seizures, and hearing loss, among other significant disabilities. Healthcare providers who understand the fundamentals of Listeria and Toxoplasma infection will have the tools to identify symptoms and high-risk behaviors, educate women to make safer decisions, and provide anticipatory guidance if a pregnant woman would become infected with either of these foodborne illnesses.

The Novel Multiple Inner Primers-Loop-Mediated Isothermal Amplification (MIP-LAMP) for Rapid Detection and Differentiation of Listeria monocytogenes

Here, a novel model of loop-mediated isothermal amplification (LAMP), termed multiple inner primers-LAMP (MIP-LAMP), was devised and successfully applied to detect Listeria monocytogenes. A set of 10 specific MIP-LAMP primers, which recognized 14 different regions of target gene, was designed to target a sequence in the hlyA gene. The MIP-LAMP assay efficiently amplified the target element within 35 min at 63 °C and was evaluated for sensitivity and specificity. The templates were specially amplified in the presence of the genomic DNA from L. monocytogenes. The limit of detection (LoD) of MIP-LAMP assay was 62.5 fg/reaction using purified L. monocytogenes DNA. The LoD for DNA isolated from serial dilutions of L. monocytogenes cells in buffer and in milk corresponded to 2.4 CFU and 24 CFU, respectively. The amplified products were analyzed by real-time monitoring of changes in turbidity, and visualized by adding Loop Fluorescent Detection Reagent (FD), or as a ladder-like banding pattern on gel electrophoresis. A total of 48 pork samples were investigated for L. monocytogenes by the novel MIP-LAMP method, and the diagnostic accuracy was shown to be 100% when compared to the culture-biotechnical method. In conclusion, the MIP-LAMP methodology was demonstrated to be a reliable, sensitive and specific tool for rapid detection of L. monocytogenes strains.

Risk factors for sporadic listeriosis in the Netherlands, 2008 to 2013

Although the disease burden of listeriosis on population level is low, on individual level the impact is high, largely due to severe illness and a high case fatality. Identification of risk factors supports and specifies public health actions needed for prevention. We performed a case–control study to determine host- and food-related risk factors for non-perinatal listeriosis in the Netherlands. Patients with non-perinatal listeriosis reported between July 2008 and December 2013 were compared with controls from a periodic control survey who completed a questionnaire in the same period. Higher age, male sex, underlying disease, especially cancer and kidney disease, and use of immunosuppressive medicine were strong risk factors for acquiring non-perinatal listeriosis. Analysis of the food consumption in the group of cases and controls with underlying diseases did not reveal any high-risk food products. Information and advice should continue to be given to persons at risk of severe listeriosis. Univariate analyses indicate that patients using gastric acid inhibitors are at risk. It is worth adding these patients to the group of susceptible persons.

Pregnancy - associated human listeriosis: Virulence and genotypic analysis of Listeria monocytogenes from clinical samples

Listeria monocytogenes, a life-threatening pathogen, poses severe risk during pregnancy, may cause abortion, fetal death or neonatal morbidity in terms of septicemia and meningitis. The present study aimed at characterizing L. monocytogenes isolated from pregnant women based on serotyping, antibiotic susceptibility, virulence genes, in vivo pathogenicity test and ERIC- and REP-PCR fingerprint analyses. The results revealed that out of 3700 human clinical samples, a total of 30 (0.81%) isolates [12 (0.80%) from placental bit (1500), 18 (0.81%) from vaginal swab (2200)] were positive for L. monocytogenes. All the isolates belonged to serogroup 4b, and were + ve for virulence genes tested i.e. inlA, inlC, inlJ, plcA, prfA, actA, hlyA, and iap. Based on the mice inoculation tests, 20 isolates showed 100% and 4 isolates 60% relative virulence while 6 isolates were non-pathogenic. Moreover, 2 and 10 isolates were resistant to ciprofloxacin and cefoxitin, respectively, while the rest susceptible to other antibiotics used in this study. ERIC- and REP-PCR collectively depicted that the isolates from placental bit and vaginal swab had distinct PCR fingerprints except a few isolates with identical patterns. This study demonstrates prevalence of pathogenic strains mostly resistant to cefoxitin and/or ciprofloxacin. The results indicate the importance of isolating and characterizing the pathogen from human clinical samples as the pre-requisite for accurate epidemiological investigations.

Increased spread and replication efficiency of Listeria monocytogenes in organotypic brain-slices is related to multilocus variable number of tandem repeat analysis (MLVA) complex

BACKGROUND

Listeria (L.) monocytogenes causes fatal infections in many species including ruminants and humans. In ruminants, rhombencephalitis is the most prevalent form of listeriosis. Using multilocus variable number tandem repeat analysis (MLVA) we recently showed that L. monocytogenes isolates from ruminant rhombencephalitis cases are distributed over three genetic complexes (designated A, B and C). However, the majority of rhombencephalitis strains and virtually all those isolated from cattle cluster in MLVA complex A, indicating that strains of this complex may have increased neurotropism and neurovirulence. The aim of this study was to investigate whether ruminant rhombencephalitis strains have an increased ability to propagate in the bovine hippocampal brain-slice model and can be discriminated from strains of other sources. For this study, forty-seven strains were selected and assayed on brain-slice cultures, a bovine macrophage cell line (BoMac) and a human colorectal adenocarcinoma cell line (Caco-2). They were isolated from ruminant rhombencephalitis cases (n = 21) and other sources including the environment, food, human neurolisteriosis cases and ruminant/human non-encephalitic infection cases (n = 26).

RESULTS

All but one L. monocytogenes strain replicated in brain slices, irrespectively of the source of the isolate or MLVA complex. The replication of strains from MLVA complex A was increased in hippocampal brain-slice cultures compared to complex C. Immunofluorescence revealed that microglia are the main target cells for L. monocytogenes and that strains from MLVA complex A caused larger infection foci than strains from MLVA complex C. Additionally, they caused larger plaques in BoMac cells, but not CaCo-2 cells.

CONCLUSIONS

Our brain slice model data shows that all L. monocytogenes strains should be considered potentially neurovirulent. Secondly, encephalitis strains cannot be conclusively discriminated from non-encephalitis strains with the bovine organotypic brain slice model. The data indicates that MLVA complex A strains are particularly adept at establishing encephalitis possibly by virtue of their higher resistance to antibacterial defense mechanisms in microglia cells, the main target of L. monocytogenes.

The global burden of listeriosis: a systematic review and meta-analysis

BACKGROUND

Listeriosis, caused by Listeria monocytogenes, is an important foodborne disease that can be difficult to control and commonly results in severe clinical outcomes. We aimed to provide the first estimates of global numbers of illnesses, deaths, and disability-adjusted life-years (DALYs) due to listeriosis, by synthesising information and knowledge through a systematic review.

METHODS

We retrieved data on listeriosis through a systematic review of peer-reviewed and grey literature (published in 1990-2012). We excluded incidence data from before 1990 from the analysis. We reviewed national surveillance data where available. We did a multilevel meta-analysis to impute missing country-specific listeriosis incidence rates. We used a meta-regression to calculate the proportions of health states, and a Monte Carlo simulation to generate DALYs by WHO subregion.

FINDINGS

We screened 11,722 references and identified 87 eligible studies containing listeriosis data for inclusion in the meta-analyses. We estimated that, in 2010, listeriosis resulted in 23,150 illnesses (95% credible interval 6061-91,247), 5463 deaths (1401-21,497), and 172,823 DALYs (44,079-676,465). The proportion of perinatal cases was 20·7% (SD 1·7).

INTERPRETATION

Our quantification of the global burden of listeriosis will enable international prioritisation exercises. The number of DALYs due to listeriosis was lower than those due to congenital toxoplasmosis but accords with those due to echinococcosis. Urgent efforts are needed to fill the missing data in developing countries. We were unable to identify incidence data for the AFRO, EMRO, and SEARO WHO regions.

FUNDING

WHO Foodborne Diseases Epidemiology Reference Group and the Université catholique de Louvain.