Mortality risk factors related to listeriosis - A meta-analysis

ListPred: A predictive ML tool for virulence potential and disinfectant tolerance in Listeria monocytogenes

Despite current surveillance and sanitation strategies, foodborne pathogens continue to threaten the food industry and public health. Whole genome sequencing (WGS) has reached an unprecedented resolution to analyse and compare pathogenic bacterial isolates. The increased resolution significantly enhances the possibility of tracing transmission routes and contamination sources of foodborne pathogens. In addition, machine learning (ML) on WGS data has shown promising applications for predicting important microbial traits such as virulence, growth potential, and resistance to antimicrobials. Many regulatory agencies have already adapted WGS and ML methods. However, the food industry hasn't followed a similarly enthusiastic implementation. Some possible reasons for this might be the lack of computational resources and limited expertise to analyse WGS and ML data and interpret the results. Here, we present ListPred, a ML tool to analyse WGS data of Listeria monocytogenes, a very concerning foodborne pathogen. ListPred relies on genomic markers and pre-trained ML models from two previous studies, and it is able to predict two important bacterial traits, namely virulence potential and disinfectant tolerance. ListPred only requires limited computational resources and practically no bioinformatic expertise, which is essential for a broad application in the food industry.

Large-scale phenotypic and genomic analysis of Listeria monocytogenes reveals diversity in the sensitivity to quaternary ammonium compounds but not to peracetic acid

Listeria monocytogenes presents a significant concern for the food industry due to its ability to persist in the food processing environment. One of the factors contributing to its persistence is decreased sensitivity to disinfectants. Our objective was to assess the diversity of L. monocytogenes sensitivity to food industry disinfectants by testing the response of 1,671 L. monocytogenes isolates to quaternary ammonium compounds (QACs) and 414 isolates to peracetic acid (PAA) using broth microdilution and growth curve analysis assays, respectively, and to categorize the isolates into sensitive and tolerant. A high phenotype-genotype concordance (95%) regarding tolerance to QACs was obtained by screening the genomes for the presence of QAC tolerance-associated genes bcrABC, emrE, emrC, and qacH. Based on this high concordance, we assessed the QAC genes' dissemination among publicly available L. monocytogenes genomes (n = 39,196). Overall, QAC genes were found in 23% and 28% of the L. monocytogenes collection in this study and in the global data set, respectively. bcrABC and qacH were the most prevalent genes, with bcrABC being the most detected QAC gene in the USA, while qacH dominated in Europe. No significant differences (P > 0.05) in the PAA tolerance were detected among isolates belonging to different lineages, serogroups, clonal complexes, or isolation sources, highlighting limited variation in the L. monocytogenes sensitivity to this disinfectant. The present work represents the largest testing of L. monocytogenes sensitivity to important food industry disinfectants at the phenotypic and genomic level, revealing diversity in the tolerance to QACs while all isolates showed similar sensitivity to PAA.

IMPORTANCE

Contamination of Listeria monocytogenes within food processing environments is of great concern to the food industry due to challenges in eradicating the isolates once they become established and persistent in the environment. Genetic markers associated with increased tolerance to certain disinfectants have been identified, which alongside other biotic and abiotic factors can favor the persistence of L. monocytogenes in the food production environment. By employing a comprehensive large-scale phenotypic testing and genomic analysis, this study significantly enhances the understanding of the L. monocytogenes tolerance to quaternary ammonium compounds (QACs) and the genetic determinants associated with the increased tolerance. We provide a global overview of the QAC genes prevalence among public L. monocytogenes sequences and their distribution among clonal complexes, isolation sources, and geographical locations. Additionally, our comprehensive screening of the peracetic acid (PAA) sensitivity shows that this disinfectant can be used in the food industry as the lack of variation in sensitivity indicates reliable effect and no apparent possibility for the emergence of tolerance.

Quantitative prediction of disinfectant tolerance in Listeria monocytogenes using whole genome sequencing and machine learning

Listeria monocytogenes is a potentially severe disease-causing bacteria mainly transmitted through food. This pathogen is of great concern for public health and the food industry in particular. Many countries have implemented thorough regulations, and some have even set 'zero-tolerance' thresholds for particular food products to minimise the risk of L. monocytogenes outbreaks. This emphasises that proper sanitation of food processing plants is of utmost importance. Consequently, in recent years, there has been an increased interest in L. monocytogenes tolerance to disinfectants used in the food industry. Even though many studies are focusing on laboratory quantification of L. monocytogenes tolerance, the possibility of predictive models remains poorly studied. Within this study, we explore the prediction of tolerance and minimum inhibitory concentrations (MIC) using whole genome sequencing (WGS) and machine learning (ML). We used WGS data and MIC values to quaternary ammonium compound (QAC) disinfectants from 1649 L. monocytogenes isolates to train different ML predictors. Our study shows promising results for predicting tolerance to QAC disinfectants using WGS and machine learning. We were able to train high-performing ML classifiers to predict tolerance with balanced accuracy scores up to 0.97 ± 0.02. For the prediction of MIC values, we were able to train ML regressors with mean squared error as low as 0.07 ± 0.02. We also identified several new genes related to cell wall anchor domains, plasmids, and phages, putatively associated with disinfectant tolerance in L. monocytogenes. The findings of this study are a first step towards prediction of L. monocytogenes tolerance to QAC disinfectants used in the food industry. In the future, predictive models might be used to monitor disinfectant tolerance in food production and might support the conceptualisation of more nuanced sanitation programs.

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.

Listeria monocytogenes and Staphylococcus aureus coinfection in a patient with multiple myeloma: Case report

Introduction

Listeria monocytogenes is a formidable pathogen that poses a significant threat to immunocompromised and might cause rare atypical forms of the disease especially complicated with Staphylococcus aureus coinfection.

Case

We present a case of a patient with L. monocytogenes meningoencephalitis, endocarditis, sepsis, and S. aureus osteomyelitis, highlighting the complexities of managing disseminated polymicrobial infection. A 64-year-old female with multiple myeloma treated with chemotherapy presented with fever, altered mental status, nausea, and diarrhea to the emergency department. During the physical examination, the patient was feverish, had a hemorrhagic rash and an abscess on the right thumb. Neurologically - nuchal rigidity was seen and the finger-nose test was abnormal. Blood tests and cerebrospinal fluid analysis were consistent with bacterial meningitis. The roentgenogram revealed osteomyelitis involving the right thumb. Later L. monocytogenes was identified in blood and cerebrospinal fluid cultures. The abscess was drained, and pus culture identified S. aureus. Echocardiography revealed vegetation on the aortic valve. The patient was initially treated with ceftriaxone, ampicillin, gentamicin, with clindamycin and ciprofloxacin for osteomyelitis and later with ampicillin/sulbactam and ciprofloxacin to cover both pathogens and pathologies. Due to an allergic reaction to ampicillin, treatment was changed to vancomycin. After 4 weeks of antibiotic therapy patient fully recovered and continued chemotherapy for multiple myeloma.

Conclusion

In conclusion, this case emphasizes the intersection of hematological malignancy, chemotherapy-related immunosuppression, and subsequent severe disseminated bacterial infections and coinfections. Prompt diagnosis and adequate treatment of the disease and its complications is key to the successful recovery.

Morbidity, Mortality, and Epidemiological Features of Clinical Invasive Listeriosis Isolates from Sentinel Surveillance in Beijing, China, 2013-2022

Listeriosis is a relatively rare but severe foodborne disease, which has significant public health concern of persons with underlying conditions and pregnant women. This study aimed to estimate the morbidity, mortality, and fatality rates of listeriosis over a 10-year period and clarify the epidemiological features of the pathogen in Beijing, China, based on voluntary reporting of sentinel surveillance. A total of 228 listeriosis cases were reported with annual morbidity rate of 1.054 per million inhabitants, including 113 maternal-neonatal cases with mean annual morbidity rate of 63.401 per million live births in Beijing from 2013 to 2022.The morbidity rate increased from 0.094 to 0.868 per million inhabitants from 2013 to 2019 (p for trend = 0.003). The overall and maternal-neonatal fatality rate were 31.82% and 42.86%, respectively. Four serogroups were identified in this study, and 1/2b predominated (89 strains). We observed the morbidity rate of listeriosis increased in Beijing over the past 10 years. Maternal-neonatal cases accounted for a higher proportion than that described in other countries, considering population base and fertility policy in China, official recommendations targeting pregnant women should be actively promoted.

Produce Safety Behaviors, Motivators, Barriers, and Beliefs in Pediatric Cancer Patient Caretakers

Cancer patients, who face increased foodborne illness susceptibility and severity, are often placed on neutropenic diets (NDs), which eliminate the consumption of fresh produce, among other foods perceived as high-risk. Such diets are clinically disputed because they have never been proven effective in reducing foodborne illness, leading to unstandardized dietary guideline content, format, and delivery methods. To inform a strategic communication approach, this study explored the produce safety handling behavior, barriers, motivators, and beliefs of pediatric cancer patient caretakers using a mixed methods convergent parallel design. A quantitative survey revealed high frequencies (>60%) for generally recommended produce safety behaviors, such as rinsing produce and washing cutting boards, and more mixed responses for restrictive produce safety behaviors, such as peeling produce and avoiding precut, self-serve, and school cafeteria produce. Total produce safety frequency scores were not significantly affected by demographic factors or Child Vulnerability Scale (CVS) scores. Qualitative interviews established a wide domain of caretaker produce safety experiences and beliefs, finding that eight of seventeen interview participants from different hospitals received produce restrictions typical of the ND. Ultimately, five caretaker archetypes were identified, with common motivators and barriers linked to materials received, child's health and perceived susceptibility, and self-efficacy beliefs. Finally, response-driven communication strategy improvements were recommended. Although sample sizes in this work were small, and further validation is advised, this work highlights the inconsistent use of the restrictive ND, advances understanding of the drivers of produce safety behaviors in cancer patient caretakers, and supports future endeavors to streamline communication strategy interventions.

Anti-biofilm effect of enzymatic hydrolysates of ovomucin in Listeria monocytogenes and Staphylococcus aureus

Despite modern advances in food hygiene, food poisoning due to microbial contamination remains a global problem, and poses a great threat to human health. Especially, Listeria monocytogenes and Staphylococcus aureus are gram-positive bacteria found on food-contact surfaces with biofilms. These foodborne pathogens cause a considerable number of food poisoning and infections annually. Ovomucin (OM) is a water-insoluble gel-type glycoprotein in egg whites. Enzymatic hydrolysis can be used to improve the bioactive properties of OM. This study aimed to investigate whether ovomucin hydrolysates (OMHs) produced using five commercial enzymes (Alcalase®, Bromelain, α-Chymotrypsin, Papain, and Pancreatin) can inhibit the biofilm formation of L. monocytogenes ATCC 15313, L. monocytogenes H7962, S. aureus KCCM 11593, and S. aureus 7. Particularly, OMH prepared with papain (OMPP; 500 μg/mL) significantly inhibited biofilm formation in L. monocytogenes ATCC 15313, L. monocytogenes H7962, S. aureus KCCM 11593, and S. aureus 7 by 85.56 %, 80.28 %, 91.70 %, and 79.00 %, respectively. In addition, OMPP reduced the metabolic activity, exopolysaccharide production (EPS), adhesion ability, and gene expression associated with the biofilm formation of these bacterial strains. These results suggest that OMH, especially OMPP, exerts anti-biofilm effects against L. monocytogenes and S. aureus. Therefore, OMPP can be used as a natural anti-biofilm agent to control food poisoning in the food industry.

Subinhibitory concentrations of glabridin from Glycyrrhiza glabra L. reduce Listeria monocytogenes motility and hemolytic activity but do not exhibit antimicrobial activity

Increases in the virulence and survival of some pathogens in the presence of subinhibitory concentrations of antibiotics have been reported. However, research on the effects of subinhibitory concentrations of antimicrobial substances derived from traditional Chinese medicine on pathogens is still insufficient. Glabridin is a well-known active isoflavone found in licorice roots that possesses a wide range of biological activities. Therefore, in this study, Listeria monocytogenes (L. monocytogenes) exposed to subinhibitory concentrations of glabridin was used as the research object. The minimum inhibitory concentration (MIC) was determined for L. monocytogenes. We investigated the impacts of subinhibitory concentrations of glabridin on the morphology, motility, biofilm formation, adherence, and survival of L. monocytogenes. The results indicated that the MIC of glabridin for L. monocytogenes was 31.25 μg/mL. At 1/8, 1/4, or 1/2 of the MIC, glabridin did not affect the growth, morphology, flagellar production, or biofilm formation of L. monocytogenes. However, subinhibitory concentrations of glabridin inhibited bacterial swimming and swarming motility and decreased the hemolytic activity of L. monocytogenes. Glabridin reduced the hemolytic activity of L. monocytogenes culture supernatants. The results also showed that subinhibitory concentrations of glabridin had no toxic effect on RAW264.7 cells but decreased the intracellular growth of L. monocytogenes in RAW264.7 cells. Furthermore, subinhibitory concentrations of glabridin triggered ROS production but did not induce MET formation in macrophages. In addition, glabridin did not enhance the capacity of L. monocytogenes to trigger METs or the extracellular killing of macrophages by METs. Thus, we conclude that subinhibitory concentrations of glabridin reduce L. monocytogenes motility and hemolytic activity but do not exhibit antimicrobial activity. Glabridin could be an interesting food additive as a bacteriostatic agent with anti-Listeria activity.

Complete genome of the Listeria monocytogenes strain AUF, used as a live listeriosis veterinary vaccine

Listeria monocytogenes (Lm) is a highly pathogenic bacterium that can cause listeriosis, a relatively rare food-borne infectious disease that affects farm, domestic, wild animals and humans as well. The infected livestock is the frequent sources of Lm. Vaccination is one of the methods of controlling listeriosis in target farm animals to prevent Lm-associated food contamination. Here we report the complete sequence of the Lm strain AUF attenuated from a fully-virulent Lm strain by ultraviolet irradiation, successfully used since the 1960s as a live whole-cell veterinary vaccine. The de novo assembled genome consists of a circular chromosome of 2,942,932 bp length, including more than 2,800 CDSs, 17 pseudogenes, 5 antibiotic resistance genes, and 56/92 virulence genes. Two wild Lm strains, the EGD and the 10403S that is also used in cancer Immunotherapy, were the closest homologs for the Lm strain AUF. Although all three strains belonged to different sequence types (ST), namely ST12, ST85, and ST1538, they were placed in the same genetic lineage II, CC7.

Case Report: A case of disseminated cutaneous listeriosis following appendicitis from Lao PDR

Background

Listeria monocytogenes is a food-borne pathogen that is a rare cause of bacteraemia and meningitis in immunosuppressed patients, and carries a high mortality rate. Cutaneous manifestations of listeriosis are rare, and are usually associated with direct inoculation of the skin.

Case

A 41-year-old woman who initially presented to a hospital in Laos with appendicitis was diagnosed with disseminated listeriosis with cutaneous involvement. Intra-abdominal pathology probably contributed to bacterial bloodstream invasion. Initial treatment with meropenem was switched to ampicillin based on best practice, however our patient died 5 days after diagnosis.

Conclusions

This case highlights listeriosis as an important cause of mortality in low- and middle-income countries, exacerbated by poor availability of laboratory diagnostics and ineffective empiric antibiotic regimens. Improvements in food hygiene, surveillance, and increased laboratory capacity are important strategies to reduce rates of infection and clinical outcomes.

PoreGlow: A split green fluorescent protein-based system for rapid detection of Listeria monocytogenes

Listeria monocytogenes, a severe foodborne pathogen causing severe diseases underscores the necessity for the development of a detection system with high specificity, sensitivity and utility. Herein, the PoreGlow system, based on split green fluorescent protein (GFP), was developed and assessed for the fast and accurate detection of L. monocytogenes. Split GFP-encapsulated liposomes were optimized for targeted analysis. The system utilizes listeriolysin O (LLO), a toxin produced by L. monocytogenes that enlarges the pores split GFP-encapsulated liposomes, to detect L. monocytogenes by measuring the fluorescent signal generated when the encapsulated GFP is released and reacted with the externally added fragment of the split GFP. The system exhibited a limit of detection of 0.17 μg/ml for LLO toxin and 10 CFU/mL for L. monocytogenes with high sensitivity and specificity and no cross-reactivity with other bacteria. The PoreGlow system is practical, rapid, and does not require sample pre-treatment, making it a promising tool for the early detection of L. monocytogenes in food products, which is crucial for preventing outbreaks and protecting public health.

Brain Abscess Caused by Listeria monocytogenes: A Rare Case of Supratentorial Neurolisteriosis

Listeria monocytogenes is a Gram-positive bacillus that presents a tropism for the central nervous system (CNS). In fact, CNS involvement occurs in over two-thirds of infections caused by this agent. Meningitis is the most common manifestation, while brain abscess is rare. We present the case of a 77-year-old male patient on corticosteroid treatment for bronchiolitis obliterans organizing pneumonia with a history of unpasteurized cheese consumption, who presented with fever and altered mental status. Brain computerized tomography scan revealed left frontal cortico-subcortical hypodensity mimicking an ischemic stroke. Subsequent magnetic resonance imaging revealed a brain abscess, and blood cultures yielded Listeria monocytogenes. A good clinical outcome was achieved after appropriate antimicrobial therapy and abscess drainage. This case underscores the importance of considering Listeria monocytogenes in CNS infections, especially in immunocompromised individuals over 65 years of age. The atypical supratentorial involvement challenges the more common rhombencephalitis presentation. Maintaining a high level of suspicion in relevant populations is crucial for timely diagnosis and intervention, especially in patients with comorbidities, who present particularly high mortality rates.

Listeria monocytogenes bacteremia developed during treatment of COVID-19

Listeria monocytogenes is an important pathogen in older patients and immunosuppressed patients, often causing bacteremia. Complications resulting from infections other than COVID-19 must also be considered during COVID-19 treatment.