Clinical features and prognostic factors of listeriosis: the MONALISA national prospective cohort study

Broad host range phage LPC-1 reduce the risk of Listeria monocytogenes contamination in different food matrices

Listeria monocytogenes forms biofilms in food and food-processing environments, entering food through cross-contamination. Phages, as antimicrobial agents, have demonstrated efficacy in addressing this issue. This study demonstrated that the LM (Listeria monocytogenes, LM) lytic phage LPC-1 isolated from livestock slaughterhouse effluent effectively lysed LM, Listeria welshimeri, Listeria innocua, and Enterococcus faecium ATCC 35667. Phage LPC-1 is a tailed phage with a non-contractile long tail, has a short incubation period, high cleavage capacity, and can be adsorbed onto the surface of bacteria within a short period. The LPC-1 phage has a genome spanning 43,466 bp with a GC content of 39% and encompasses 67 coding sequences. Notably, LPC-1's genome displayed significant homologies to various non-Listeria phages. Experimental tests under simulated refrigerated conditions revealed that LPC-1 effectively diminished the presence of LM in milk, pork, and both eggshells and egg liquid, indicating its bacteriostatic properties. Moreover, LPC-1 hindered biofilm formation and enhanced biofilm eradication. Consequently, these findings endorse the potential of phage LPC-1 as a prospective antimicrobial agent specifically suited for controlling LM contamination in the food industry, given its proven safety and efficacy.

Severe listeriosis in intensive care units: insights from a retrospective multicentric study

BACKGROUND

Listeriosis is a rare but severe foodborne infection, particularly affecting immunocompromised individuals and older adults. Severe cases may lead to neurolisteriosis and sepsis, necessitating intensive care unit (ICU) admission. This study aims to analyze the demographic characteristics, clinical presentation, microbiological findings, treatments, and outcomes of critically ill patients with Listeria infections in the ICU.

METHODS

A retrospective multicenter study was conducted across 23 French hospitals over a 10-year period, including ICU patients with culture-confirmed Listeria monocytogenes infections. Data on demographics, comorbidities, ICU admission characteristics, biological and microbiological parameters, treatments, and outcomes were collected. The primary outcome was ICU mortality. A multivariable logistic regression model was used to identify factors associated with mortality in patients with neurological manifestations.

RESULTS

A total of 110 patients were included, with a median age of 68 years; 61% were male, and 71% were immunocompromised. Neurological involvement was present in most cases. Invasive mechanical ventilation was required in 58% of patients, and vasopressor support in 44%. ICU and in-hospital mortality rates were 25% and 32%, respectively. Among patients with neurolisteriosis, each 1-point decrease in Glasgow Coma Scale score at admission was associated with increased mortality (OR, 1.22; 95% CI 1.05-1.45; p = 0.009), as were higher cerebrospinal fluid (CSF) protein levels (OR, 1.56; 95% CI 1.15-2.41; p = 0.028). Steroid use was not significantly associated with reduced mortality (OR, 0.30; 95% CI 0.07-1.05; p = 0.076).

CONCLUSION

Listeriosis requiring ICU admission is associated with high morbidity and mortality, particularly in older and immunocompromised patients. The severity of these infections is reflected by the frequent need for organ support. Further research is needed to clarify the potential role of steroids in neurolisteriosis.

Comparative analysis of virulence in Listeria monocytogenes: Insights from genomic variations and in vitro cell-based studies

Listeria monocytogenes is a significant foodborne pathogen capable of crossing the intestinal barrier and causing invasive listeriosis. This study focused on 37 L. monocytogenes strains isolated from food and clinical samples in the Shanghai region between 2020 and 2023. The in vitro cell models were used to assess the bacteria's ability to cross the intestinal barrier, as well as their adhesion and invasion capabilities in placental cells. Whole-genome analysis of the bacterial strains was also performed. The results showed that strains from lineage I exhibited significantly higher translocation ability across the Caco-2 barrier, as well as higher adhesion and invasion rates in JEG-3 cells, compared to strains from lineage II. Strains from serogroup IIb demonstrated significantly higher adhesion and invasion rates in JEG-3 cells than those from serogroups IIa and IIc. Clinical isolates had significantly higher translocation ability across the Caco-2 barrier, and higher adhesion and invasion rates in JEG-3 cells, compared to food-derived strains. Mutations in the inlA gene were detected in ST9 and ST121 strains, which may be a potential cause of the reduced virulence observed in these ST types. The presence of LIPI-4 in ST87 strains and LIPI-3 in ST3 strains may also explain the high virulence of these ST types strains. The results of this study, by integrating in vitro virulence phenotypes with genomic data, further enhance the understanding of virulence differences among different bacterial strains.

Genomic characterization of Listeria monocytogenes isolated from normally sterile human body fluids in Lithuania from 2016 to 2021

Listeria monocytogenes is a saprophytic gram-positive bacterium and opportunistic foodborne pathogen that can cause listeriosis in humans. The incidence of listeriosis has been rising globally and, despite antimicrobial treatment, the mortality rates associated with the most severe forms of listeriosis such as sepsis, meningitis and meningoencephalitis remain high. The notification of listeriosis in humans is mandatory in Lithuania, and up to 20 cases are reported annually. However, no studies have described the detailed virulence and antimicrobial susceptibility profiles of any clinical L. monocytogenes strains in Lithuania. Accordingly, this study aimed to describe the antibiotic susceptibility of invasive L. monocytogenes and perform in-depth characterization of strains isolated from patients with neuroinfections through whole-genome sequencing. A total of 70 isolates were collected, mostly from infected patients aged 65 or older, between 2016 and 2021 : 41 (58.6%) from blood, 19 (27.1%) from cerebrospinal fluid, 5 (7.1%) from wounds, 1 (1.4%) from pleural fluid and 1 (1.4%) from a brain abscess. Two phylogenetic lineages were identified-I (n = 16/70, 22.9%) and II (n = 54/70, 77.1%)-along with three serogroups-IIa (n = 53/70, 75.7%), IVb (n = 16/70, 22.9%), and IIc (n = 1/70, 1.4%). Genomic analysis of 20 isolates showed a high level of diversity with seven genotypes: ST6 (n = 6), ST155 (n = 5), ST8 (n = 4), ST504 (n = 2) and singletons for ST37, ST451 and ST2. Phylogenetic analysis clustered these isolates into two clades defined by serogroups IVb and IIa. Notably, five isolates were clustered tightly together (difference of 6-48 core SNPs from reference and 0, 4 or 44 SNPs from each other) with ST155, previously reported in a European outbreak. Comparison with publicly available L. monocytogenes genomes did not identify unique clusters or genotypes. No acquired antimicrobial resistance genes were identified. Our study highlights the complementary value of whole-genome sequencing in routine PCR-based surveillance in Lithuania. This is the first study to characterize and compare genomes for L. monocytogenes associated with neuroinfections in Lithuania using whole-genome sequencing. The retrospective detection of the ST155 clone underscores the need for a review and strengthening of epidemiological surveillance strategies in clinical and non-clinical settings in Lithuania.

Pregnancy-related listeriosis in Spain

BACKGROUND

Pregnant women are at high risk of acquiring listeriosis, resulting in severe fetal and neonatal outcomes.

METHODS

All hospitalizations with a listeriosis diagnosis in pregnant women (obstetric listeriosis) and/or newborns (neonatal listeriosis) in Spain from 2000 to 2021 were examined using the National Registry of Hospital Discharges, employing ICD-9 and -10 coding lists.

RESULTS

A total of 540 and 450 hospital admissions for obstetric listeriosis and neonatal listeriosis were identified, respectively, with 146 adverse fetal-neonatal outcomes (miscarriage, fetal loss, stillbirth, and neonatal death). The incidence of obstetric listeriosis, neonatal listeriosis, and adverse fetal-neonatal outcomes (5.7, 4.7, and 1.5 per 100,000 deliveries, respectively) rose significantly from 2000 to 2021. No maternal deaths were recorded among women hospitalized with obstetric listeriosis. However, 9.8 % experienced miscarriage, related to bacteremia (OR=2.46), 6.3 % fetal loss and 5.9 % stillbirths, associated with chorioamnionitis (OR=3.42), which was identified in 77.7 % of 254 deliveries. Overall, 51.1 % of newborns developed sepsis, 58.9 % prematurity, 26.9 % ARDS, and 9.8 % died. ARDS (OR=2.76) and prematurity (OR=5.07) were associated with perinatal death in newborns with listeriosis. Pregnancy-related listeriosis was associated with increased risks of miscarriage (OR=1.75), intrauterine death (OR=17), preterm labor (OR=8.78), fetal distress (OR=2.10), cesarean section (OR=1.68), and stillbirth (OR=23.57).

CONCLUSIONS

Admissions for obstetric listeriosis and neonatal listeriosis in Spain have risen significantly from 2000 to 2021. Pregnancy-related listeriosis has a deleterious impact on fetal and neonatal outcomes, including miscarriages, fetal loss, stillbirth, and neonatal death. Surveillance, prevention, and prompt management of pregnant women with listeriosis and newborns with neonatal infection are warranted.

Effects of Decentralized Sequencing on National Listeria monocytogenes Genomic Surveillance, Australia, 2016-2023

We assessed turnaround times in the national Listeria monocytogenes genomic surveillance system in Australia before and after decentralized sequencing. Using 1,204 samples collected during 2016-2023, we observed statistically significant reductions in median time from sample collection to issuance of national genomic surveillance report to 26 days, despite sample numbers doubling in 2022 and 2023. During 2016-2018, all jurisdictions referred samples to the National Listeria Reference Laboratory for sequencing and analysis, but as jurisdictional sequencing capacity increased, 4 jurisdictions transitioned to sequencing their own samples and referring sequence data to the national laboratory. One jurisdiction had well-established genomics capacity, transitioned without noticeable disruption, and continued to improve. Another 3 jurisdictions initially had increased turnaround times, highlighting the need for defined sequence referral mechanisms. Overall, timeliness and throughput improved, and sequencing decentralization strengthened Australia's genomic surveillance system while maintaining timeliness. The practices described could be beneficial and achievable in other countries.

Bacterial Meningitis

Community-acquired bacterial meningitis has a high fatality rate, and survivors may have significant long-term neurologic sequelae, despite appropriate antibiotics. Although cerebral spinal fluid cultures and/or PCR testing are necessary to establish a definitive case of bacterial meningitis, antibiotic administration should never be delayed while waiting to obtain a lumbar puncture. Patients with suspected bacterial meningitis should be started on empiric antibiotics and adjunctive dexamethasone within an hour of presentation, with subsequent regimens targeted toward the identified pathogen. Vaccines are an important tool to minimize the risk of bacterial meningitis, and use should be encouraged by adults at higher risk.

The Relationship Between Potential Listeria monocytogenes Exposure and Diet Quality and Dietary Intake During Pregnancy: A Cross-Sectional Analysis in Australian Women

BACKGROUND

Research conducted over two decades ago indicated that more frequent consumption of foods potentially harbouring Listeria monocytogenes is associated with higher nutrient intakes but also higher risk of miscarriage. However, the influence of potential exposure to Listeria monocytogenes on pregnant women's diet quality is yet to be examined. Additionally, advancements in agricultural practices and food consumption trends in recent years may have led to changes in pregnant women's dietary intake. Therefore, the present study aimed to evaluate the associations between potential L. monocytogenes exposure and dietary quality, and dietary intake in two contemporary cohorts of pregnant women in Australia.

METHODS

A secondary analysis of two combined pregnancy cohorts of women aged ≥ 19 years with a singleton pregnancy from the Newcastle, New South Wales (n = 441) and Perth, Western Australia (n = 1197) was conducted. Potential L. monocytogenes exposure was estimated by the Listeria Food Exposure Score (LFES), dietary intake was assessed using the Australian Eating Survey and diet quality using the Australian Recommended Food Score. Pearson's correlation and linear regression analyses were performed to estimate the associations between potential L. monocytogenes exposure and dietary quality and intake, with adjustment for potential confounders.

RESULTS

Data from 1638 women (mean [SD] age 32.0 [5.0] years, 57.8% born in Australia) were included. The median (IQR) gestational age was 35 (34-36) weeks and 43.5% of women had no prior pregnancies. A higher LFES (i.e., more frequent consumption of potential food sources of L. monocytogenes) was significantly associated with higher diet quality score (r = 0.60, p < 0.001), higher intakes of nutrient-dense core foods (r = 0.11-0.43, p < 0.001), and higher micronutrient intakes (r = 0.24-0.52, all p < 0.001).

CONCLUSION

More frequent consumption of foods that potentially harbour Listeria monocytogenes is associated with higher diet quality and nutrient intakes. Further research is needed to identify how to support women to achieve optimal diet quality and nutrient intakes while simultaneously minimising risk of listeriosis.

Clinical impact and safety of brain biopsy in unexplained central nervous system disorders: a real-world cohort study

OBJECTIVE

A substantial part of central nervous system (CNS) disorders remains unexplained, despite various new and minimally invasive diagnostic techniques. Within this rapidly developing diagnostic field, the precise role of brain biopsy is unknown. We aimed to study the clinical impact and safety of brain biopsies in unexplained CNS disorders.

METHODS

In this retrospective cohort study, we included all adult patients who were referred for a diagnostic work-up to our academic center with neuro-inflammatory, neuro-oncological, and neuro-infectious expertise and underwent a brain biopsy between January 2010 and December 2023. Typical cases of CNS neoplasms and infections were not analyzed. Brain biopsies were evaluated with respect to diagnostic and therapeutic impact and complication risk.

RESULTS

Brain biopsy was performed in 587 patients. Ninety-four patients with a CNS disorder of unknown cause, with 107 biopsies, were analyzed (44% female, median age 58 years). Postoperative diagnoses included brain tumors/lymphomas (37/94, 39%), inflammatory disorders (11/94, 12%), infections (8/94, 9%), autoimmune encephalitis (8/94, 9%), and primary angiitis of the CNS (4/94, 4%). Diagnostic yield of brain biopsy was 62%, increasing up to 72% after repeat biopsies, as 10 additional patients were diagnosed with a brain tumor. In 77% of patients, brain biopsy changed the treatment strategy. Symptomatic intracranial hemorrhage occurred in 4 of 107 brain biopsies (4%).

INTERPRETATION

In a selected population of patients with unexplained CNS disorders, clinical impact of brain biopsies is high, while being relatively safe. A multidisciplinary team approach is fundamental in establishing optimal indication for brain biopsy and subsequent treatment decisions.

Comparative evaluation of sanitation strategies against Listeria monocytogenes on food-contact surfaces in enoki mushroom (Flammulina velutipes) processing facilities

We investigated strategies to reduce Listeria monocytogenes contamination on food contact surfaces during enoki mushroom processing. Chemical disinfectants and thermal treatments were evaluated on conveyor belts, stainless steel, plastic surfaces, and Velcro strips. Without organic matter, chemical disinfectants effectively reduced L. monocytogenes, with stainless steel showing the highest susceptibility. Organic matter decreased disinfectant efficacy, but sodium hypochlorite remained most effective on stainless steel. Peracetic acid was more effective on conveyor belts and plastic surfaces than on stainless steel. Combining peracetic acid with dry heating synergistically reduced L. monocytogenes on Velcro strips. Moist heat at 70 °C alone was insufficient, but when combined with hot air drying, it effectively reduced L. monocytogenes on Velcro strips. Our findings emphasize the importance of surface-specific strategies combining chemical disinfection and thermal treatment for eliminating L. monocytogenes in mushroom processing environments.

Maternal-Fetal Listeriosis in China: Clinical and Genomic Characteristics From an ST8 Listeria monocytogenes Case

Background

Listeriosis, a severe foodborne infection caused by Listeria monocytogenes, poses significant risks during pregnancy, including maternal-neonatal transmission. This study describes the clinical and genomic characteristics of an sequence type 8 (ST8) L. monocytogenes strain involved in maternal-neonatal transmission during pregnancy.

Methods

Clinical presentation, diagnostic process, and treatment outcomes of the case were documented in detail. Whole-genome sequencing (WGS) and subsequent genomic analyses were performed on L. monocytogenes isolates obtained from the maternal and neonatal blood cultures.

Results

A 33-week pregnant woman presented with decreased fetal movements and underwent an emergency cesarean delivery. Postpartum, she developed a high fever, and blood cultures from both the mother and the neonate the day after caesarean delivery confirmed L. monocytogenes infection. WGS revealed that the isolates belonged to serotype 1/2a, ST8, clonal complex (CC) 8, and lineage II. Both isolates exhibited susceptibility to first-line antibiotics, including penicillin and ampicillin, and contained virulence and stress adaptation genes such as LIPI-1 and SSI-1. Phylogenetic analysis based on cg-SNP linked the clinical isolates to foodborne ST8 strains from Huzhou and Shanghai, suggesting potential contamination routes.

Conclusion

This case highlights the importance of timely diagnosis and effective antibiotic management in preventing adverse pregnancy outcomes. It also underscores the need for enhanced food safety surveillance and genomic monitoring of L. monocytogenes to better understand the transmission dynamics and to avoid the extension of a foodborne infection.

Impact of immunosuppression on Listeria monocytogenes infection in Spain

INTRODUCTION

Immunosuppression (IS) determines a higher risk of disease severity from Listeria monocytogenes (LM) infection.

METHODS

We examined the epidemiology of IS in all patients hospitalized with LM in Spain from 2000 to 2021 in the National Registry of Hospital Discharges. IS was defined by liver disease (LD), diabetes mellitus (DM), chronic kidney disease (CKD), solid organ transplantation (SOT), bone marrow transplantation (BMT), primary immunodeficiencies (ID), systemic autoimmune diseases (SAD), solid organ neoplasms (SON), and hematological neoplasms (HN).

RESULTS

Among 8,152 admissions with LM, 48% were IS. There was an increase from 39.5% to 60% during the study period, mainly driven by rises in DM (from 12.6% to 26.2%), SON (from 9.9% to 17.5%), CKD (from 4.4% to 16.3%), HN (from 6.6% to 13.4%), and LD (from 4.9% to 6.6%) (p < 0.001 for all trends). IS fatality rate was higher than in non-IS (22.4% vs 11.3%; OR = 2.09). The proportion of LM patients with IS among LM in-hospital deaths increased from 57.1% in 2000 to 67.95% in 2021 (p < 0.001). Fatality risk differed according to baseline IS condition: LD (OR = 2.42), CKD (OR = 1.49), SON (OR 3.01) and HN (OR 1.45).

CONCLUSIONS

The prevalence of IS among patients hospitalized with LM in Spain has risen over the past two decades, with a growing impact on fatality rates. These findings should prompt further efforts to prevent and manage properly LM infection.

Listeria monocytogenes use multiple mechanisms to disseminate from the intestinal lamina propria to the mesenteric lymph nodes

Listeria monocytogenes are facultative intracellular bacterial pathogens that cause foodborne disease in humans. The bacteria can use the surface protein InlA to invade intestinal epithelial cells or transcytose across M cells in the gut, but it is not well understood how the bacteria traffic from the underlying lamina propria to the draining mesenteric lymph nodes (MLN). Previous studies indicated that L. monocytogenes associated with both monocytes and dendritic cells in the intestinal lamina propria. We show here that CCR2-/- mice had a significant reduction in Ly6Chi monocytes in the MLN but no change in bacterial burden following foodborne infection; thus, dissemination of L. monocytogenes associated with monocytes is not required for colonization of the MLN. To block CCR7-mediated trafficking of dendritic cells from the lamina propria, we treated mice with anti-VEGFR3 antibody (clone AFL4) prior to and during infection but did not see a change in dendritic numbers in the MLN as had been previously reported with other anti-VEGFR3-specific antibodies. However, increasing the number of circulating dendritic cells by treating mice with rFlt3L resulted in a significant increase in L. monocytogenes in the lymph nodes that drain the small intestine and the spleen. Whole-mount fluorescent microscopy of lymphatic vessels following ligated loop infection revealed both free-floating L. monocytogenes and cell-associated bacteria within lymphatic vessels. Together, these results suggest that L. monocytogenes can use multiple, redundant mechanisms to disseminate from the gut tissue to the MLN.

IMPORTANCE

Consumption of the foodborne bacterial pathogen Listeria monocytogenes results in a wide spectrum of human disease from mild self-limiting gastroenteritis to life-threatening infections of the bloodstream, brain, and placenta. It is not well understood how the bacteria migrate from the intestines to the draining mesenteric lymph nodes, which are thought to serve as the last barrier to prevent systemic infections. Results presented here reveal multiple redundant mechanisms L. monocytogenes can use to disseminate from the ileum or colon to the mesenteric lymph nodes.

A novel virulent core genome multilocus sequence type CT 11424 of Listeria monocytogenes isolate causing stillbirth in Bangladesh

BACKGROUND

Listeria monocytogenes is a foodborne pathogen that can lead to severe pregnancy outcomes. This study reports the clinical and genomic characteristics of a Listeria-mediated stillbirth identified in January 2022 through the Child Health and Mortality Prevention Surveillance (CHAMPS) project in Bangladesh. The Lm-BD-CHAMPS-01 isolate was recovered from the blood and cerebrospinal fluid (CSF) of a male stillborn. Maternal history, clinical, and demographic data were collected by the CHAMPS surveillance platform. An expert panel evaluated all reports to determine the role of L. monocytogenes infection in the causal chain of stillbirth. Genomic characterization included multilocus sequence typing (MLST), core genome MLST (cgMLST), serotyping, and the presence or absence of virulence genes. Genetic divergence and phylogenetic analyses were conducted to determine the relationship with other reported isolates globally.

RESULTS

The isolate Lm-BD-CHAMPS-01 was identified as a novel cgMLST CT11424. It belonged to ST 308, Serotype 4b, Clonal Complex 1, and Phylogenetic Lineage 1. Key L. monocytogenes virulence genes facilitating the crossing of the placental barrier, including full-length inlA, LIPI-1, and LIPI-3, were detected. The isolate was closely related to clinical L. monocytogenes isolates, as determined by GrapeTree based on cgMLST. SNP-based phylogenetic analysis found Lm-BD-CHAMPS-01 to be the most distant from other CC1 isolates in the database. Possible sources of infection included the consumption of contaminated raw vegetables or exposure to pigeons.

CONCLUSIONS

This is the first genome sequence of clinical L. monocytogenes from Bangladesh, which also caused stillbirth. Rural healthcare professionals should be aware of L. monocytogenes infection risks during pregnancy. Pregnant women should be counseled on the dangers of exposure to animals or birds and consumption of potentially contaminated raw food to prevent adverse pregnancy outcomes due to L. monocytogenes infection.

[Community acquired bacterial meningitis in adults]

Bacterial meningitis is a rare but severe disease with a high mortality. The most frequent pathogens in adults are pneumococcus, meningococcus and Listeria. The most important key symptoms are headache, meningism and fever; however, the absence of individual cardinal symptoms does not exclude the diagnosis. The empirical treatment consists of ceftriaxone and ampicillin, supplemented with dexamethasone as needed. It should be initiated without delay if bacterial meningitis is suspected. Before this, two pairs of blood cultures should be obtained followed by a lumbar puncture. An elevated intracranial pressure must be excluded via cerebral computed tomography before performing a lumbar puncture only in patients with confirmation of impaired consciousness, focal neurological deficits or epileptic seizures. In such cases treatment is initiated immediately after obtaining blood cultures but before the lumbar puncture. The identification and management of a focus are essential and should be conducted on the day of admission.

Listeria Meningitis as an Indication of Undiagnosed Primary Immune Deficiency, Activated Phosphoinositide 3-Kinase Delta Syndrome: A Case Report

INTRODUCTION

Listeria monocytogenes is a Gram-positive bacillus that causes severe infections mainly in newborns, pregnant women, immunocompromised individuals, and elderly. In this report, we present a case of immune dysregulation that presented with invasive Listeria infection despite the absence of these risk factors.

CASE

A previously healthy 5-year-old girl developed L. monocytogenes meningitis, which is unusual given her age and lack of typical risk factors. The patient initially presented with fever, diarrhea and altered mental status, unresponsive to empiric antibiotic treatment. Besides clinical diagnosis of meningitis, laboratory tests revealed pleocytosis and positive polymerase chain reaction test for L. monocytogenes in cerebrospinal fluid. Despite initial improvement, the patient developed proteinuria and hypertension and was later diagnosed with focal class 3 lupus nephritis following a renal biopsy. Given the atypical nature of her L. monocytogenes infection, persistent organomegaly, and lupus nephritis, further immunological evaluation was conducted. Genetic testing revealed a de-novo gain-of-function mutation in the PIK3CD gene, confirming the diagnosis of Activated Phosphoinositide 3-Kinase Delta Syndrome 1 (APDS1), a rare primary immunodeficiency characterized by lymphoproliferation and autoimmunity. The patient was started on immunoglobulin replacement therapy and prophylactic trimethoprim-sulfamethoxazole. No recurrence of severe infection occurred during 2 years of follow-up.

CONCLUSION

This case underscores the importance of considering underlying immune dysregulations in pediatric patients with atypical presentation of Listeria infections.

Airborne Staphylococcus aureus Exposure Induces Depression-like Behaviors in Mice via Abnormal Neural Oscillation and Mitochondrial Dysfunction

Airborne Staphylococcus aureus exists widely in the natural environment and is closely related to human health. Growing evidence indicates that environmental air pollution elevates the risk of depressive disorders. However, the potential role of airborne S. aureus in the development of depression remains unclear. This study aims to elucidate the neurotoxic effects and potential mechanisms associated with depression caused by airborne S. aureus. Mice were randomly divided into four groups, and the experimental groups with environmental S. aureus were at 4.89 × 102, 8.89 × 105, and 1.27 × 108 CFU/m3 during four consecutive weeks. Airborne S. aureus exposure contributed to depression-like behaviors in mice, especially in the high-concentration group. The electroencephalography signal analysis identified uncoupling of theta and gamma bands and a shift of the beta rhythm toward delta oscillation in the medial prefrontal cortex of mice. Neuropathological analysis showed uplifted neuroinflammation and elevated levels of oxidative stress in the brain. Neuroinflammation and oxidative stress resulted in mitochondrial dysfunction, which could lead to apoptosis. Together, this study provides a strong basis for understanding the adverse outcomes of airborne S. aureus on mental health disorders.

Monitoring cellular dynamics upon infection using a holotomography-based approach

Many intracellular bacteria interfere with mitochondrial dynamics or target other organelles, thereby inducing a specific cellular response that could emerge as a strategy of the pathogen to ensure its survival, or as a form of defense employed by the host cell to restrict dissemination. In this context, the concomitant monitoring of both pathogen migration and (intra)cellular dynamics in live cells emerges as a pivotal aspect for the comprehension of the infection sequence and to visualize the pathogen-mediated remodeling that could occur to the entire cellular system. Holotomographic microscopy can be used to achieve this goal, allowing the simultaneous analysis of both bacterial movement and intracellular alteration for extended periods of time, with high spatial resolution and avoiding side-effects due to phototoxicity. Here we provide a holotomography-based approach to detect Listeria monocytogenes dynamics and its effects on the entire cellular system at morphological level.

Experience and Perspectives on Antibacterial Therapy for Listeriosis in a Tertiary Teaching Hospital in China: A Retrospective Study and Health Care Provider Survey

Listeriosis is a rare, life-threatening bacterial infection. Prompt, appropriate antibiotic treatment is essential to save lives. We aimed to investigate antibiotic selection and listeriosis knowledge among health care providers. We first performed a retrospective study on patients with listeriosis who were treated in a hospital in China from January 2013 to March 2023. Patient characteristics and antibiotic selections were recorded. Antibiotics were classified as effective or ineffective based on the efficacy classifications listed in The Sanford Guide to Antimicrobial Therapy (50th edition). We then conducted a questionnaire survey of health care providers to investigate their listeriosis knowledge and practices between April 2023 to May 2023. Fifteen listeriosis patients were identified, with a case fatality rate of 26.7% (4/15). Empirical treatments assessed as effective antibiotics or ineffective antibiotics were given to 33.3% (5/15) and 66.7% (10/15) of the patients, respectively. After Listeria monocytogenes was identified, 40% (6/15) of the patients received an adjustment to their antibiotics, although 50% (3/6) patients still received ineffective antibiotics. The questionnaire survey of 77 participating health care providers showed that 32.9% (24/73) of the clinicians were unaware of the appropriate antibiotics for listeriosis. Most participants (83.1%, 64/77) would read the drug sensitivity report before selecting the antibiotics. The selection of effective antibiotics differed between the infectious diseases department and other departments (p < 0.001), but did not differ between junior title and other titles (p = 0.088). Most patients with listeriosis did not receive appropriate antibiotics, which might have accounted for the high fatality rate, and may have resulted from inadequate listeriosis knowledge. More education and correct reporting of drug sensitivity results are urgently needed.

A Binational Sample-Initiated Retrospective Outbreak Investigation of Listeria monocytogenes Infections in the United States and Canada Linked to Enoki Mushrooms Imported from China 2022-2023

In 2022, the U.S. Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), U.S. state and local partners, the Public Health Agency of Canada (PHAC), and the Canadian Food Inspection Agency (CFIA) conducted a binational sample-initiated retrospective outbreak investigation (SIROI) of Listeria monocytogenes illnesses linked to enoki mushrooms. The FDA and CDC investigated the first known L. monocytogenes outbreak linked to enoki mushrooms from 2016 to 2020, making the 2022 outbreak the second time this pathogen-commodity pair was investigated by FDA and CDC. The 2022 outbreak included six ill people, all of whom were hospitalized. Epidemiologic, laboratory, and traceback evidence led to multiple public health actions, including voluntary recalls by firms, public communications about the outbreak, and FDA's country-wide Import Alert for enoki mushrooms from China. This SIROI illustrates the importance of surveillance sampling, national and international coordination of efforts, and rapid information sharing to identify and stop foodborne outbreaks on a global scale. To reduce the risk of listeriosis illnesses linked to contaminated enoki mushrooms, public health and regulatory agencies in the United States and Canada remain committed to conducting comprehensive surveillance for Listeria in foods and in people, efficiently investigating identified outbreaks, and implementing control measures to potentially minimize the impact of future outbreaks.

Kinetic and proteomic studies in milk show distinct patterns among major Listeria monocytogenes clones

Listeria monocytogenes, a contaminant of raw milk, includes hypervirulent clonal complexes (CC) like CC1, CC4, and CC6, highly overrepresented in dairy products when compared to other food types. Whether their higher prevalence in dairy products is the consequence of a growth advantage in this food remains unknown. We examined growth kinetics of five L. monocytogenes isolates (CC1, CC4, CC6, CC9, and CC121) at 37 and 4 °C in ultra-high temperature (UHT) milk and raw milk. At 4 °C, hypovirulent CC9 and CC121 isolates exhibit better growth parameters in UHT milk compared to the hypervirulent CC1, CC4, and CC6 isolates. CC9 isolate in raw milk at 4 °C exhibited the fastest growth and the highest final concentrations. In contrast, hypervirulent isolates (CC1, CC4, and CC6) displayed better growth rates in UHT milk at 37 °C, the mammalian host temperature. Proteomic analysis of representative hyper- (CC1) and hypovirulent (CC9) isolates showed that they respond to milk cues differently with CC-specific traits. Proteins related to metabolism (such as LysA or different phosphotransferase systems), and stress response were upregulated in both isolates during growth in UHT milk. Our results show that there is a Listeria CC-specific and a Listeria CC-common response to the milk environment. These findings shed light on the overrepresentation of hypervirulent L. monocytogenes isolates in dairy products, suggesting that CC1 and CC4 overrepresentation in dairy products made of raw milk may arise from contamination during or after milking at the farm and discard an advantage of hypervirulent isolates in milk products when stored at refrigeration temperatures.

Differential stress responsiveness determines intraspecies virulence heterogeneity and host adaptation in Listeria monocytogenes

Microbial pathogenesis is mediated by the expression of virulence genes. However, as microbes with identical virulence gene content can differ in their pathogenic potential, other virulence determinants must be involved. Here, by combining comparative genomics and transcriptomics of a large collection of isolates of the model pathogen Listeria monocytogenes, time-lapse microscopy, in vitro evolution and in vivo experiments, we show that the individual stress responsiveness of L. monocytogenes isolates determines their respective levels of virulence in vivo and reflects their degree of host adaptation. The transcriptional signature that accounts for the heterogeneity in the virulence of L. monocytogenes species is mediated by the stress response regulator SigB and driven by differential stress responsiveness. The tuning of SigB pathway responsiveness is polygenic and influenced by multiple, individually rare gene variations. This study reveals an overarching determinant of microbial virulence, challenging the paradigm of accessory virulence gene content as the major determinant of intraspecies virulence heterogeneity.

Informative Value of a Sample Investigation with a Predefined Sample Size using the Example of Listeria monocytogenes in Food Safety

Foodborne diseases, especially those caused by zoonotic agents, pose a significant threat to human health. Food business operators are therefore responsible for producing safe food. To do this, they must regularly carry out appropriate sample investigations to detect zoonotic agents in their food before it leaves the factory. Depending on the issue investigated, there may be legal requirements for food business operators, usually specifying minimum sample sizes, such as Commission Regulation (EU) No 2073/2005. However, in most cases, there is no information on the precision, and therefore, on the significance of the results for these sample sizes. Regulatory veterinary authorities have a control function and, as a result, they are required to regularly evaluate the available investigations and their results. In addition, in certain crisis situations (e.g., foodborne outbreaks or suspected food contamination), authorities may guide food business operators in their investigations and conduct their own investigations to assess food safety measures. In such cases, as there are no legally defined sample sizes to be taken, the appropriate sample sizes must be determined by the authorities. This can lead to a conflict between the need for feasibility and the need for conclusiveness of the investigation potentially being a challenge for the regulatory authority in charge. This paper highlights the importance of thoughtful study design and the critical communication of available results by veterinary authorities on the background of a use case involving Listeria monocytogenes findings in a crisis situation. Using the minimum sample size, n = 5, required by Commission Regulation (EU) No 2073/2005 for the pathogen Listeria monocytogenes as a guide, the uncertainties associated with small sample sizes are highlighted. It also aims to facilitate the evaluation of studies performed and the assessment of further sample sizes.

A Quick Sequential Organ Failure Assessment (qSOFA) Score Greater than 1 and Shortened Ampicillin Use Predict Death and One-Year Mortality in Hospitalized Patients with Non-Perinatal Invasive Listeriosis: A Retrospective Analysis of 118 Consecutive Cases

Listeria monocytogenes causes listeriosis, a serious foodborne illness with a high mortality rate, especially in vulnerable populations. It accounts for 19% of foodborne deaths, with invasive cases having a mortality rate of up to 44%, leading to conditions like meningitis, bacteremia, and meningoencephalitis. However, the prognostic factors remain unclear. This study examines the hospital outcomes of invasive listeriosis and identifies risk factors for in-hospital and one-year mortality. We analyzed the electronic medical records of 118 hospitalized patients with non-perinatal, culture-proven invasive listeriosis collected over a 21-year period. The in-hospital mortality rate was 36.4%, with only 33.1% surviving one year and 22.0% surviving two years. The key findings indicate that a quick Sequential Organ Failure Assessment (qSOFA) score of ≥2 (OR 106.59, p < 0.001), respiratory failure (OR 7.58, p = 0.031), and shorter ampicillin duration (OR 0.53, p = 0.012) independently predicted poorer in-hospital outcomes. Additionally, a qSOFA score of ≥2 (OR 8.46, p < 0.001) and shorter ampicillin duration (OR 0.65, p < 0.001) were linked to higher one-year mortality. This study is the first to identify a qSOFA score of ≥2 as a significant marker for high-risk invasive listeriosis patients, with poorer outcomes linked to a qSOFA score of ≥2, respiratory failure, and shorter ampicillin use.

Listeria monocytogenes in Fruits and Vegetables: Antimicrobial Resistance, Biofilm, and Genomic Insights

BACKGROUND/OBJECTIVES

Listeria monocytogenes is a foodborne pathogen that can infect both humans and animals and cause noninvasive gastrointestinal listeriosis or invasive listeriosis. The objectives of this study were to determine the genetic diversity of L. monocytogenes; the genes associated with its resistance to antibiotics, benzalkonium chloride (BC), and cadmium chloride (CdCl2); and its biofilm formation.

METHODS

A total of 132 fresh fruits (44 samples) and vegetables (88 samples) were selected for this study. The genetic diversity of the isolates and the genes associated with their antibiotic resistance were determined using PCR amplification; meanwhile, their levels of susceptibility to antibiotics were determined using the agar diffusion method. Their levels of resistance to BC and CdCl2 were determined using the minimum inhibitory concentration method, and their capacity for biofilm formation was evaluated using the crystal violet staining method.

RESULTS

A total of 17 L. monocytogenes strains were collected: 12.8% (17/132) from fresh fruits and vegetables in this study. The isolates of L. monocytogenes belonged to phylogenetic groups I.1 (29.4% (5/17); serotype 1/2a) and II.2 (70.5% (12/17); serotype 1/2b); strains containing Listeria pathogenicity islands (LIPIs) were also identified at prevalence rates of 100% for LIPI-1 and LIPI-2 (17/17), 29.4% for LIPI-3 (5/17), and 11.7% for LIPI-4 (2/17). The antibiotic susceptibility tests showed that the L. monocytogenes isolates exhibited six different multiresistant patterns, with multiple antibiotic resistance (MAR) index of ≥0.46 (70.5%; 12/17); additionally, the genes Ide, tetM, and msrA, associated with efflux pump Lde, tetracycline, and ciprofloxacin resistance, were detected at 52.9% (9/17), 29.4% (5/17), and 17.6% (3/17), respectively. The phenotypic tests showed that 58.8% (10/17) of cadmium-resistant L. monocytogenes isolates had a co-resistance of 23.5% (4/17) to BC. Finally, all strains of L. monocytogenes exhibited moderate biofilm production.

CONCLUSIONS

The results of this study contribute to our understanding of the persistence and genetic diversity of L. monocytogenes strains isolated from fresh fruits and vegetables; in addition, their resistance to CdCl2, which is correlated with co-resistance to BC disinfectant, is helpful for the food industry.

Neonatal Bacterial Meningitis: What Have We Learned From the Last Decade?

Bacterial meningitis is a devastating disease with significant morbidity and mortality, especially in neonates and young infants. The overall incidence of meningitis has decreased with focused screening, public health interventions, and vaccination, but the disease remains a significant concern in high-risk groups. In this review, we provide an update on bacterial meningitis in children younger than age 60 days, including epidemiology, clinical presentation, diagnostic approaches, treatment, and prognosis. [Pediatr Ann. 2024;53(11):e425-e432.].

Neurobrucellosis Presenting with Motor Damage or Hearing Loss, and Use of Steroids are Associated with a Higher Risk of Sequelae or Relapse: A Systematic Review of Individual Participant Data

BACKGROUND

Neurobrucellosis presents diverse clinical challenges and risks of long-term complications.

OBJECTIVE

We aimed to assess the relationship between the duration of antibiotic therapy, clinical factors, and the outcome of neurobrucellosis with a case report combined with a systematic review of the literature.

METHODS

We present a case of a 31 years-old man successfully treated at our Institution. We then searched Ovid MEDLINE, Embase and Scopus for articles that encompassed neurobrucellosis cases, duration of treatment, and outcome. The primary outcome was to assess an association between the duration of treatment and the risk of sequelae or relapses. Univariate, multivariate and sensitivity analysis were carried out to define which variables affect​ed​ the clinical outcome. Quality assessment was performed using a dedicated tool.

RESULTS

A total of 123 studies were included, totaling 221 patients. Median duration of treatment was 4 months (IQR 3 - 6), 69% patients recovered without sequelae, 27% had sequelae. Additionally, five patients had a relapse, and 4 patients died. Multivariate analysis found that the duration of treatment, age, and the use of ceftriaxone were not associated with a higher risk of sequelae or relapses. A significant association was found for corticosteroids use (OR 0.39, 95% IC 0.16 - 0.96, p = 0.038), motor impairment (OR 0.29, 95% IC 0.14 - 0.62, p = 0.002), and hearing loss (OR 0.037, 95% IC 0.01 - 0.11, p < 0.001).

CONCLUSIONS

This study highlights the variability in clinical presentations and treatment approaches for neurobrucellosis. Patients with factors indicating higher sequelae risk require meticulous follow-up.

High density genomic surveillance and risk profiling of clinical Listeria monocytogenes subtypes in Germany

BACKGROUND

Foodborne infections such as listeriosis caused by the bacterium Listeria monocytogenes represent a significant public health concern, particularly when outbreaks affect many individuals over prolonged time. Systematic collection of pathogen isolates from infected patients, whole genome sequencing (WGS) and phylogenetic analyses allow recognition and termination of outbreaks after source identification and risk profiling of abundant lineages.

METHODS

We here present a multi-dimensional analysis of > 1800 genome sequences from clinical L. monocytogenes isolates collected in Germany between 2018 and 2021. Different WGS-based subtyping methods were used to determine the population structure with its main phylogenetic sublineages as well as for identification of disease clusters. Clinical frequencies of materno-foetal and brain infections and in vitro infection experiments were used for risk profiling of the most abundant sublineages. These sublineages and large disease clusters were further characterised in terms of their genetic and epidemiological properties.

RESULTS

The collected isolates covered 62% of all notified cases and belonged to 188 infection clusters. Forty-two percent of these clusters were active for > 12 months, 60% generated cases cross-regionally, including 11 multinational clusters. Thirty-seven percent of the clusters were caused by sequence type (ST) ST6, ST8 and ST1 clones. ST1 was identified as hyper- and ST8, ST14, ST29 as well as ST155 as hypovirulent, while ST6 had average virulence potential. Inactivating mutations were found in several virulence and house-keeping genes, particularly in hypovirulent STs.

CONCLUSIONS

Our work presents an in-depth analysis of the genomic characteristics of L. monocytogenes isolates that cause disease in Germany. It supports prioritisation of disease clusters for epidemiological investigations and reinforces the need to analyse the mechanisms underlying hyper- and hypovirulence.

The Deceptive Reassurance of a "Negative" Test - A Difficult Case Highlighting the BioFire© Meningitis/Encephalitis Panel and Medical Heuristics

Purpose: Neurolisteriosis is a difficult neurologic infectious disease to diagnose. Here, we present a case in which the diagnosis was suspected, but repeated testing for the pathogen was negative. Ultimately the diagnosis was made after the patient iatrogenically worsened. Results: This prompted an investigation into the widely used diagnostic test, the BioFire© Meningitis/Encephalitis Panel. Although the company reports high sensitivities and specificities for the panel, real world studies have demonstrated insufficient evidence that all 14 pathogens tested on the panel have similar results. Conclusion: This case is a reminder of the heuristics involved in medicine and how with every medical advancement, clinicians should always go back to the fundamentals of history-taking and physical examinations to ensure no steps have been overlooked in the diagnosis and management of challenging cases.

Relevance of microbiological cultures of cord blood and placental swabs in the rapid diagnosis of preterm newborn infection due to Listeria monocytogenes: A case report

Listeria monocytogenes (Lm) is a Gram-positive bacterium causing listeriosis, a rare but severe foodborne infection, particularly impactful during pregnancy. Maternal-fetal transmission can lead to adverse fetal outcomes, yet symptoms in mothers may be nonspecific, delaying intervention. Despite the severity, the mechanisms of vertical transmission remain unclear. This report describes a case of rapid Lm diagnosis in a preterm newborn using cord blood and placental swabs. A 31-week pregnant woman presented with abdominal pain, diarrhea, and reduced fetal movements after consuming raw sushi. Laboratory findings indicated infection, and she vaginally delivered a live infant with placental and fetal abscesses. Cultures confirmed Lm, with swift diagnosis aided by molecular syndromic testing. The neonate received appropriate antibiotics and was asymptomatic by the end of treatment. This case underscores the need for the rapid diagnosis of maternal-fetal listeriosis, as it poses significant risks during pregnancy, including preterm birth and neonatal complications. Current diagnostic methods often delay treatment. This report emphasizes the use of innovative molecular techniques for early diagnosis, which is crucial in managing neonatal infections, especially in preterm newborns.

Clinical and Bacterial Characteristics of Bloodstream Infections Caused by Listeria monocytogenes in Western China

Objective

Bloodstream infections (BSIs) caused by Listeria monocytogenes are linked to high mortality of the patients. Case-specific details related to this disease and causative strains in different districts remain to be characterized.

Methods

In this study, medical data of BSIs admitted to West China Hospital from October 2017 to March 2023 were retrieved from the hospital information system. The in vitro antimicrobial susceptibility testing and whole-genome sequencing were performed for L. monocytogenes strains isolated from blood specimens. The genetic relationship of these strains with those in public databases was also analyzed.

Result

The in-hospital mortality of L. monocytogenes BSIs was 25.7% (9/35). The changes in consciousness and elevated serum C-reactive protein (CRP) level were found to be the differential factors of L. monocytogenes BSIs (P < 0.05). All the 27 strains studied were susceptible to ampicillin, meropenem, and erythromycin. Only 22.2% of them were susceptible to trimethoprim-sulfamethoxazole. The Listeria pathogenicity islands 1 (LIPI-1), truncated LIPI-2, and multiple virulence-related genes outside the LIPIs were determined from these strains. Also, 12 sequence types (STs) and 12 clonal complexes (CCs) were identified and classified into clonal lineages I (9/27, 33.3%) and lineages II (18/27, 66.7%), demonstrating genetic differences with the strains in the database. ST451/CC11 (5/27, 18.5%) and ST8/CC8 (4/27, 14.8%) were the common genotypes.

Conclusions

The consciousness change and elevated serum CRP level were found to be the differential factors of L. monocytogenes BSIs. Considering the high virulence of the strains, it is needed to pay more attention to the dissemination of the predominant genotype.

Clinical and microbiological characteristics and follow-up of invasive Listeria monocytogenes infection among hospitalized patients: real-world experience of 16 years from Hungary

PURPOSE

Invasive Listeria monocytogenes infection is rare, but can lead to life-threatening complications among high-risk patients. Our aim was to assess characteristics and follow-up of adults hospitalized with invasive L. monocytogenes infection.

METHODS

A retrospective observational cohort study was conducted at a national referral center between 2004 and 2019. Patients with proven invasive listeriosis, defined by the European Centre for Disease Prevention and Control criteria, were included. Data collection and follow-up were performed using the hospital electronic system, up until the last documented visit. The primary outcome was in-hospital all-cause mortality, secondary outcomes included residual neurological symptoms, brain abscess occurrence, and requirement for intensive care unit (ICU) admission.

RESULTS

Altogether, 63 cases were identified (57.1% male, median age 58.8 ± 21.7 years), and 28/63 developed a complicated disease course (44.4%). At diagnosis, 38/63 (60.3%) presented with sepsis, 54/63 (85.7%) had central nervous system involvement, while 9/63 (14.3%) presented with isolated bacteremia. Frequent clinical symptoms included fever (53/63, 84.1%), altered mental state (49/63, 77.8%), with immunocompromised conditions apparent in 56/63 (88.9%). L. monocytogenes was isolated from blood (37/54, 68.5%) and cerebrospinal fluid (48/55, 87.3%), showing in vitro full susceptibility to ampicillin and meropenem (100% each), gentamicin (86.0%) and trimethoprim/sulfamethoxazole (97.7%). In-hospital all-cause mortality was 17/63 (27.0%), and ICU admission was required in 28/63 (44.4%). At discharge, residual neurological deficits (11/46, 23.9%) and brain abscess formation (6/46, 13.0%) were common.

CONCLUSION

Among hospitalized adult patients with comorbidities, invasive L. monocytogenes infections are associated with high mortality and neurological complications during follow-up.

Inhibitory effect and mechanism of oregano essential oil on Listeria monocytogenes cells, toxins and biofilms

Listeria monocytogenes (L. monocytogenes) is a prevalent foodborne pathogen with a remarkable capacity to form biofilms on utensil surfaces. The Listeriolysin O (LLO) exhibits hemolytic activity, which is responsible for causing human infections. In this study, we investigated the inhibitory effect and mechanism of oregano essential oil (OEO) on L. monocytogenes, evaluated the effects on its biofilm removal and hemolytic activity. The minimum inhibitory concentration (MIC) of OEO against L. monocytogenes was 0.03 % (v/v). L. monocytogenes was treated with OEO at 3/2 MIC for 30 min the bacteria was decreased below the detection limit (10 CFU/mL) in PBS and TSB (the initial bacterial load was about 6.5 log CFU/mL). The level of L. monocytogenes in minced pork co-cultured with OEO (15 MIC) about 2.5 log CFU/g lower than that in the untreated group. The inhibitory mechanisms of OEO against planktonic L. monocytogenes encompassed perturbation of cellular morphology, elevation in reactive oxygen species levels, augmentation of lipid oxidation extent, hyperpolarization of membrane potential, and reduction in intracellular ATP concentration. In addition, OEO reduced biofilm coverage on the surface of glass slides by 62.03 % compared with the untreated group. Meanwhile, OEO (1/8 MIC) treatment reduced the hemolytic activity of L. monocytogenes to 24.6 % compared with the positive control. Molecular docking suggested carvacrol and thymol might reduce the hemolytic activity of L. monocytogenes. The results of this study demonstrate that OEO exhibits inhibitory effects against L. monocytogenes, biofilms and LLO, which had potential as natural antimicrobial for the inhibition of L. monocytogenes.

A 48-year-old man with fever, nauseous, vomiting, and dizzy: A CARE case report

RATIONALE

Listeria monocytogenes (LM) is an important foodborne bacterium, and LM meningoencephalitis is rare in clinical practice, with poor prognosis in severe patients. It is prone to misdiagnosis in clinical practice. We first reported a case of severe LM meningoencephalitis with muscle lesions and evaluated the comprehensive condition.

PATIENT CONCERNS

A 48-year-old man had a fever and was admitted to the neurology department due to dizziness, nausea, and vomiting for 20 days.

DIAGNOSES

LM meningoencephalitis complicated with muscle lesions.

INTERVENTIONS

We used moxifloxacin 0.4 g, qd, meropenem 2 g, q8h, and dexamethasone 10 mg, qd to reduce exudation and adhesion. Then due to consideration of side effects, we increased the dose of ampicillin by 2 g, q4h, stopped using meropenem and moxifloxacin, and turned to maintenance treatment with dexamethasone and ampicillin. We comprehensively managed his vital signs and physical organ functions, we also controlled some comorbidities. During the hospitalization period thereafter, we used intravenous anti-infection treatment with moxifloxacin 0.4 g, qd, ampicillin 0.5 g, q4h.

OUTCOMES

Half a year later, the reexamination showed only protein elevation in cerebrospinal fluid and hydrocephalus in MRI. Afterward, the symptoms did not recur again. The patient recovered well after discharge.

LESSONS

LM meningoencephalitis complicated with lower limb muscle lesions is clinically rare. This report focuses on relevant treatment plans, which provide value for the examination and comprehensive management of patients with LM infection in the future.

Increased incidence and mortality from Listeria monocytogenes infection in Spain

OBJECTIVES

Listeria monocytogenes (LM) is a health threat worldwide given its high mortality and the growing of high-risk susceptible populations.

METHODS

All hospitalizations with a diagnosis of LM in the National Registry of Hospital Discharges were examined in Spain from 2000 to 2021.

RESULTS

A total of 8152 hospital admissions with LM were identified. The mean age was 59.5 years and 48% were immunosuppressed (IS). The rate of LM hospitalizations increased from 5 per 1 million population in 2000 to 8.9 in 2021 (p < 0.001). A foodborne outbreak in Andalusia determined a sharp increase in admissions with LM during 2019. The COVID-19 pandemic and lockdowns were associated with a decrease in LM admissions. The overall in-hospital mortality was 16.7%. The number of deaths in patients hospitalized with LM rose from 7.8 per 100,000 deceased in 2000 to 18 in 2021 (p < 0.001). After adjustment, age >65 years (odds ratio [OR] = 2.16), sepsis (OR = 2.60), meningoencephalitis (OR = 1.72), endocarditis (OR = 2.0), neonatal listeriosis (OR = 2.10) and IS (OR = 2.09) were associated with mortality.

CONCLUSIONS

The number of patients hospitalized with LM in Spain has increased significantly from 2000 to 2021. The increase in the rate of admissions and deaths was largely driven by the growing proportion of elderly and IS patients.

Acute infections of the central nervous system in children and adults: diagnosis and management

Central nervous system infections are due to different microorganisms such as viruses, bacteria, mycobacteria, fungi, amoebas, and other parasites. The etiology depends on multiple risk factors, and it defines the infection location because some microorganisms prefer meninges, brain tissue, cerebellum, brain stem or spinal cord. The microorganisms induce diseases in the nervous system through direct invasion, neurotoxin production, and the triggered immune response. To determine the infection etiology, there are several diagnostic tests which may be conducted with cerebrospinal fluid, blood, respiratory and stool samples. These tests include but are not limited to direct microscopic examination of the sample, stains, cultures, antigenic tests, nucleic acid amplification tests, metagenomic next-generation sequencing, immunologic biomarker and neuroimaging, especially contrast-enhanced magnetic resonance imaging. The treatment may consist of specific antimicrobial treatment and supportive standard care. Since viruses have no specific antiviral treatment, antimicrobial treatment is mainly targeted at non-viral infections. This article will focus on diagnosis and treatment of acute acquired infections of the central nervous system beyond the neonatal period. The discussion defines the disease, provides the clinical presentation, explains the etiology and risk factors, and briefly mentions potential complications. This updated review aims to provide the reader with all the elements needed to adequately approach a patient with a central nervous system infection. Mycobacterium tuberculosis infection, Cryptococcus spp. infection and vaccines are not within the scope of this article.

Granulocytes in cerebrospinal fluid of adults suspected of a central nervous system infection: a prospective study of diagnostic accuracy

PURPOSE

Cerebrospinal fluid (CSF) granulocytes are associated with bacterial meningitis, but information on its diagnostic value is limited and primarily based on retrospective studies. Therefore, we assessed the diagnostic accuracy of CSF granulocytes.

METHODS

We analyzed CSF granulocytes (index test) from all consecutive patients in two prospective cohort studies in the Netherlands. Both studies included patients ≥ 16 years, suspected of a central nervous system (CNS) infection, who underwent a diagnostic lumbar puncture. All episodes with elevated CSF leukocytes (≥ 5 cells per mm3) were selected and categorized by clinical diagnosis (reference standard).

RESULTS

Of 1261 episodes, 625 (50%) had elevated CSF leukocytes and 541 (87%) were included. 117 of 541 (22%) were diagnosed with bacterial meningitis, 144 (27%) with viral meningoencephalitis, 49 (9%) with other CNS infections, 76 (14%) with CNS autoimmune disorders, 93 (17%) with other neurological diseases and 62 (11%) with systemic diseases. The area under the curve to discriminate bacterial meningitis from other diagnoses was 0.97 (95% confidence interval [CI] 0.95-0.98) for CSF granulocyte count and 0.93 (95% CI 0.91-0.96) for CSF granulocyte percentage. CSF granulocyte predominance occurred in all diagnostic categories. A cutoff at 50% CSF granulocytes gave a sensitivity of 94% (95% CI 90-98), specificity of 80% (95% CI 76-84), negative predictive value of 98% (95% CI 97-99) and positive predictive value of 57% (95% CI 52-62).

CONCLUSION

CSF granulocytes have a high diagnostic accuracy for bacterial meningitis in patients suspected of a CNS infection. CSF granulocyte predominance occurred in all diagnostic categories, limiting its value in clinical practice.

[Community-Acquired Bacterial Meningoencephalitis: The New Guideline]

Updating the vaccination recommendations against meningococci and pneumococci, in particular the introduction of the B vaccine as the standard vaccination for infants from January 2024 and the adaptation of the pneumococcal vaccination strategy for infants and adults aged 60 and over with the latest conjugate vaccines (PCV13, PCV15, PCV20).Emphasis on the need for rapid diagnostic lumbar puncture and simultaneous serum and cerebrospinal fluid analysis to increase diagnostic precision. The introduction of procalcitonin (PCT) in serum as an additional biomarker to differentiate between bacterial and viral meningitis.The use of multiplex PCR as a supplement, not a replacement, for standard diagnostics to speed up pathogen identification.Adaptation of antibiotic recommendations based on the current resistance situation, in particular for meningococcal meningitis, consideration of penicillin G only after resistance testing.Clarification of the areas and duration of use of dexamethasone in bacterial meningitis, particularly in pneumococcal meningitis and the controversial data situation in Listeria meningitis.New findings on the safe use of heparin in septic sinus thrombosis without increased risk of hemorrhage.

Challenging boundaries: Organ transplants from donors with Listeria central nervous system infections

Pretransplant mortality rates in the US remain high and are connected to effective organ donation and utilization. Thus, there is a need to maximize the utilization of available donors. In some cases, this has been safely achieved using organs from donors with infectious complications. For example, several studies describe the use of organs from donors with bacterial meningitis due to pathogens such as Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenza, and Escherichia coli, with good outcomes. Listeria is an aerobic and facultatively anaerobic, nonspore-forming, Gram-positive rod that can affect the central nervous system, causing meningitis and meningoencephalitis. Due to its virulence, ability to cause intracellular infection, and lack of clinical data, people dying with listeria may not be evaluated for organ donation, may not have organs recovered, or may have their organs recovered but not transplanted. Herein, we describe the outcomes of 7 solid organ transplant recipients who received organs from 2 donors with Listeria monocytogenes central nervous system infection.

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

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

[Molecular characterization of Listeria monocytogenes isolates from human and food sources in Argentina, 2018-2023]

Human listeriosis is an infectious disease caused by Listeria monocytogenes. The invasive form of this disease leads to a high rate of hospitalizations and fatality. The main mode of transmission is through contaminated ready-to-eat foods such as dairy, vegetables and meat products. The knowledge of the diversity and population dynamics of isolates collected from human and food sources is essential for the detection of clusters and the identification of common sites of infection. The aim of this study was the molecular characterization of L. monocytogenes isolates in Argentina. We sequenced a total of 63 isolates, 35 from human and 28 from food sources, collected between 2018 and 2023. Our genomic study divided the isolates into two lineages, four serogroups, 17 sequence types and 15 clonal complexes (CCs). The hypervirulent clone CC1 (lineage I; serogroup IVb) predominated in human and food samples. The phylogenomic analysis showed a high and possible epidemiological relationship between isolates from human and/or food sources, suggesting the presence of transmission chains in our country. These findings highlight the need to strengthen genomic surveillance of L. monocytogenes in Argentina. The identification of geographic distribution and characteristics of predominant and emerging clones from human and food sources might help to focus action plans and public health policies better directed at the control and prevention of listeriosis.

Characteristics of Clinical Isolates of Listeria monocytogenes in Sichuan, China, in 2022 Based on Whole Genome Sequencing Analysis

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 Infections in Hematopoietic Cell Transplantation Recipients: Clinical Manifestations and Risk Factors. A Multinational Retrospective Case-Control Study from the Infectious Diseases Working Party of the European Society for Blood and Marrow Transplantation

Listeriosis is rare after hematopoietic stem cell transplantation (HCT). Little is known about listeriosis in this population. In this retrospective international case-control study, we evaluated 41 listeriosis episodes occurring between 2000 and 2021 in HCT recipients (111 transplant centers in 30 countries) and assessed risk factors for listeriosis by comparisons with matched controls. The 41 listeriosis episodes (all due to Listeria monocytogenes [LM]) occurred in 30 allogeneic (allo)-HCT recipients and 11 autologous (auto)-HCT recipients at a median of 6.2 months (interquartile range [IQR], 1.6 to 19.3 months) post-HCT. The estimated incidence was 49.8/100,000 allo-HCT recipients and 13.7/100,000 auto-HCT recipients. The most common manifestations in our cohort were fever (n = 39; 95%), headache (n = 9; 22%), diarrhea, and impaired consciousness (n = 8 each; 20%). Four patients (10%) presented with septic shock, and 19 of 38 (50%) were severely lymphocytopenic. Thirty-seven patients (90%) had LM bacteremia. Eleven patients (27%) had neurolisteriosis, of whom 4 presented with nonspecific signs and 5 had normal brain imaging findings. Cerebrospinal fluid analysis revealed high protein and pleocytosis (mainly neutrophilic). Three-month mortality was 17% overall (n = 7), including 27% (n = 3 of 11) in patients with neurolisteriosis and 13% (n = 4 of 30) in those without neurolisteriosis. In the multivariate analysis comparing cases with 74 controls, non-first HCT (odds ratio [OR], 5.84; 95% confidence interval [CI], 1.10 to 30.82; P = .038); and lymphocytopenia <500 cells/mm3 (OR, 7.54; 95% CI, 1.50 to 37.83; P = .014) were significantly associated with listeriosis. There were no statistically significant differences in background characteristics, immunosuppression, and cotrimoxazole prophylaxis between cases and controls. HCT recipients are at increased risk for listeriosis compared to the general population. Listeriosis cause severe disease with septic shock and mortality. Neurolisteriosis can present with nonspecific signs and normal imaging. Lymphocytopenia and non-first HCT are associated with an increased risk of listeriosis, and cotrimoxazole was not protective.

Listeria monocytogenes-associated spontaneous bacterial peritonitis in France: a nationwide observational study of 208 cases

BACKGROUND

Listeriosis is a foodborne infection caused by Listeria monocytogenes. Three main forms of listeriosis are well characterised, but little is known about L monocytogenes-associated spontaneous bacterial peritonitis. We used data from the French national surveillance of listeriosis to perform a nationwide retrospective study.

METHODS

All patients with L monocytogenes isolated by culture from a peritoneal fluid sample in France between April 1, 1993, and Dec 31, 2022, were included. Individuals for whom bacterial peritonitis was not confirmed and those who also had another type of invasive listeriosis were excluded. A standardised checklist was used to collect demographic, clinical, and biological data as well as antibiotic treatment and follow-up data. The primary outcome was to determine the characteristics of L monocytogenes-associated spontaneous bacterial peritonitis. We did descriptive analyses and assessed risk factors for 1-month mortality using an exploratory multivariable Cox model analysis.

FINDINGS

Among the 8768 L monocytogenes cases reported, 208 (2%) were patients with L monocytogenes-associated spontaneous bacterial peritonitis. Mean age was 65 years (SD 13), 50 (24%) of 208 patients were female, and 158 (76%) were male (no data on race or ethnicity were available). 200 (98%) of 205 patients with L monocytogenes-associated spontaneous bacterial peritonitis with available data had immunosuppressive comorbidities, including cirrhosis (148 [74%] of 201 with available data), ongoing alcoholism (58 [62%] of 94), and ongoing neoplasia (60 [31%] of 195). Causes of ascites included cirrhosis (146 [70%] of 208), ongoing neoplasia (26 [13%]), end-stage heart failure (13 [6%]), and peritoneal dialysis (11 [5%]). Among those with available data, presentation was pauci-symptomatic and non-specific; only 67 (50%) of 135 patients presented with fever, 49 (37%) of 132 with abdominal pain, and 27 (21%) of 129 with diarrhoea. 61 (29%) of 208 patients were dead at 1 month, 92 (44%) were dead at 3 months, and 109 (52%) were dead at 6 months after diagnosis. Ongoing neoplasia (hazard ratio 2·42 [95% CI 1·05-5·56]; p=0·039), septic shock (8·03 [2·66-24·02]; p=0·0021), and high blood leukocyte count (1·05 [1·00-1·09]; p=0·045) were independently associated with 1-month mortality.

INTERPRETATION

Despite the non-specific and mild presentation of L monocytogenes-associated spontaneous bacterial peritonitis, the outcome is poor and similar to that of neurolisteriosis, and so identification of L monocytogenes in ascitic fluid samples requires urgent parenteral amoxicillin-based treatment to avoid a fatal outcome.

FUNDING

Institut Pasteur, Inserm, and French Public Health Agency.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Clinical and genomic features of a Listeria monocytogenes fatal case of meningitis in Madagascar

Listeriosis constitutes a significant public health threat due to its high mortality rate. This study investigates the microbiological and genomic characteristics of Listeria monocytogenes isolates in Madagascar, where listeriosis is a notifiable disease. The analysis focuses on a fatal case of meningeal listeriosis in a 12-year-old child. Genomic analysis revealed a novel cgMLST type (L2-SL8-ST8-CT11697; CC8, serogroup Iia) with typical virulence and antibiotic resistance profiles. These isolates, unique to Madagascar, formed an independent clade in the phylogenetic tree. This study presents the first genomic characterization of Listeria isolates in Madagascar, highlighting the necessity of ongoing genomic surveillance to strengthen listeriosis prevention and control strategies in the region.

Endocytosis at the maternal-fetal interface: balancing nutrient transport and pathogen defense

Endocytosis represents a category of regulated active transport mechanisms. These encompass clathrin-dependent and -independent mechanisms, as well as fluid phase micropinocytosis and macropinocytosis, each demonstrating varying degrees of specificity and capacity. Collectively, these mechanisms facilitate the internalization of cargo into cellular vesicles. Pregnancy is one such physiological state during which endocytosis may play critical roles. A successful pregnancy necessitates ongoing communication between maternal and fetal cells at the maternal-fetal interface to ensure immunologic tolerance for the semi-allogenic fetus whilst providing adequate protection against infection from pathogens, such as viruses and bacteria. It also requires transport of nutrients across the maternal-fetal interface, but restriction of potentially harmful chemicals and drugs to allow fetal development. In this context, trogocytosis, a specific form of endocytosis, plays a crucial role in immunological tolerance and infection prevention. Endocytosis is also thought to play a significant role in nutrient and toxin handling at the maternal-fetal interface, though its mechanisms remain less understood. A comprehensive understanding of endocytosis and its mechanisms not only enhances our knowledge of maternal-fetal interactions but is also essential for identifying the pathogenesis of pregnancy pathologies and providing new avenues for therapeutic intervention.

Clinical Characteristics and Fatality Risk Factors for Patients with Listeria monocytogenes Infection: A 12-Year Hospital-Based Study in Xi'an, China

INTRODUCTION

Listeriosis is a severe food-borne disease caused by Listeria monocytogenes infection. The data of listeriosis in Xi'an population are limited. The aim of this study is to evaluate the clinical features and fatality risk factors for listeriosis in three tertiary-care hospitals in Xi'an, China METHODS: The characteristics of demographic data, underlying diseases, clinical manifestations, laboratory indicators, cranial imaging examination, antibiotics therapeutic schemes, and clinical outcomes were collected between 2011 and 2023. Logistic regression analysis was performed.

RESULTS

Seventy-one etiologically confirmed listeriosis patients were enrolled, including 12 neonatal and 59 non-neonatal cases. The majority of neonatal listeriosis presented as preterm (50%) and fetal distress (75%). The main clinical manifestations of non-neonatal listeriosis included fever (88%), headache (32%), disorder of consciousness (25%), vomiting (17%), abdominal pain (12%), and convulsions (8%). The fatality rate in neonatal cases was higher than in non-neonatal listeriosis (42 vs. 17%). Although no deaths were reported in maternal listeriosis, only two of 23 patients had an uneventful obstetrical outcome. Five maternal listeriosis delivered culture-positive neonates, three of whom decreased within 1 week post-gestation due to severe complications. Twenty-eight cases were neurolisteriosis and 43 cases were bacteremia. Neurolisteriosis had a higher fatality rate compared with bacteremia listeriosis (36 vs. 12%). The main neuroradiological images were cerebral edema/hydrocephalus, intracranial infection, and cerebral hernia. Listeria monocytogenes showed extremely low resistance to ampicillin (two isolates) and penicillin (one isolate). The fatality risk factors were the involvement of the central nervous system, hyperbilirubinemia, and hyponatremia for all enrolled subjects. Hyperuricemia contributed to the elevation of fatality risk in non-neonatal listeriosis.

CONCLUSIONS

When the patients suffered with symptoms of fever and central nervous system infection, they should be alert to the possibility of listeriosis. Early administration of ampicillin- or penicillin-based therapy might be beneficial for recovery of listeriosis.