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.

Phenotypic and genotypic antimicrobial resistance of Listeria monocytogenes: an observational study in France.

Background: Large-scale studies are needed to clarify antimicrobial resistance in the foodborne pathogen Listeria monocytogenes (Lm) and the effectiveness of listeriosis treatment options. Here we examined the antimicrobial resistance patterns in Lm over time and assessed genotype-phenotype concordances. Methods: We analyzed 5339 Lm isolates (2908 clinical and 2431 food isolates) collected in France and overseas territories, between 2012 and 2019. Whole genome sequencing was performed for all isolates and antimicrobial resistance profiles inferred from draft assemblies. Antimicrobial susceptibility towards 22 antimicrobials was determined for all clinical isolates, and in food isolates with acquired resistance genes. Findings: All tested isolates were resistant to at least 3 different classes of antimicrobials, consistent with Lm intrinsic traits. Acquired antimicrobial resistance in Lm was rare (2.23% isolates) and more prevalent in food (mainly lineage II) compared to clinical isolates (mainly lineage I) (3.74% vs 0.98%, p < 0.0001), and in isolates with disinfectants or stress resistance traits (e.g. bcrABC, 20.20% vs 7.20%, p < 0.0001), suggesting co-selection of resistance in food-production environments. Acquired antimicrobial resistance could be predicted from genomes with high accuracy (>99%), except for ciprofloxacin. Acquired antimicrobial phenotypes were towards tetracyclines (mostly due to tetM), trimethoprim (dfrD), lincosamides (lnuG), macrolides (ermB, mphB) and phenicols (fexA). Interpretation: The reference treatment for listeriosis (aminopenicillins/aminoglycosides) remains effective, with no acquired resistance observed. Continuous surveillance of antimicrobial resistance in clinical and food isolates is crucial to detect the emergence of novel resistance. Funding: Institut Pasteur, INSERM, Santé Publique France, Investissement d'Avenir program Laboratoire d'Excellence 'Integrative Biology of Emerging Infectious Diseases' (ANR-10-LABX-62-IBEID).

Clinical and genomic features of Listeria monocytogenes-associated mesenteric lymphadenitis in a cat.

BACKGROUND: Listeriosis is a severe foodborne infection caused by Listeria monocytogenes, an important foodborne pathogen of animals and humans. Listeriosis is a rare disease in cats. OBJECTIVE: To describe the clinical, diagnostic imaging, histological, and microbiological features of L. monocytogenes-associated mesenteric lymphadenitis in a cat. ANIMALS: Listeria monocytogenes-associated mesenteric lymphadenitis was confirmed in a cat by histology and microbiology. RESULTS: Two distinct isolates of L. monocytogenes were cultured from the affected mesenteric lymph node and whole genome sequencing was performed. CONCLUSION AND CLINICAL IMPORTANCE: This report should alert veterinary clinicians and microbiologists to the syndrome, which may have implications for health and food safety in animals and humans.

Genome-Based Characterization of Listeria monocytogenes, Costa Rica.

Genomic data on the foodborne pathogen Listeria monocytogenes from Central America are scarce. We analyzed 92 isolates collected during 2009-2019 from different regions in Costa Rica, compared those to publicly available genomes, and identified unrecognized outbreaks. Our findings suggest mandatory reporting of listeriosis in Costa Rica would improve pathogen surveillance.

Long-term neurological and neurodevelopmental outcome of neonatal listeriosis in France: a prospective, matched, observational cohort study.

BACKGROUND: Maternal-neonatal listeriosis is a rare and serious infection. The long-term outcome of surviving infants with early-onset or late-onset listeriosis remains unknown. We aimed to determine the long-term neurological and neurodevelopmental outcome of neonatal listeriosis. METHODS: In this prospective, matched, observational cohort study, we evaluated children born with microbiologically confirmed maternal-neonatal listeriosis in the French MONALISA cohort. At age 5 years, children underwent neurological and neurodevelopmental assessments of sensory deficits, executive function, adaptive behaviour, and cognitive and motor coordination function. The cognitive domain was assessed using the French version of the Wechsler Preschool and Primary Scale of Intelligence, fourth edition, and scored by Full Scale Intelligence Quotient (FSIQ). The motor domain was assessed by physical examination designed to screen for cerebral palsy and developmental coordination disorder. Executive functioning was assessed using the statue and inhibition subtests of Neuropsychological Assessment, second version. The sensory domain was assessed by parental interview, medical report, and clinical assessment. Adaptive behaviour was measured using the Vineland-II behaviour scale from parent-reported assessments of functional communication, socialisation, daily living, and motor skills. Results were compared with gestational age-matched children from two national prospective cohorts: EPIPAGE-2 (preterm infants) and ELFE (term infants from a general population of infants >32 weeks gestation). This study is registered with ClinicalTrials.gov (NCT02580812). FINDINGS: Of 59 children who were alive and eligible to participate in the study, 53 (median age 5 years, IQR 5-6) were enrolled for neurodevelopmental assessments between Oct 26, 2016, and Oct 29, 2019. Of 53 children, 31 (58%) had been born preterm, 22 (42%) had early-onset systemic infection, 18 (34%) had early-onset non-systemic infection, and six (11%) had late-onset systemic infection, all with meningitis. 29 (66%) of 44 children, in whom neurodevelopmental disabilities scores were available, developed at least one disability; eight (18%) children had severe neurodevelopmental disabilities. Of four children with late-onset infection and in whom neurodevelopmental disabilities scores were available, three developed at least one neurodevelopmental disability. Neurological and neurodevelopmental outcomes of children with neonatal listeriosis did not differ from those of gestational age-matched control children without infection (relative risk [RR] of at least one disability 0·99 [95% CI 0·65-1·51; p=0·97]; RR of FSIQ less than -1 SD 0·92 [0·54-1·54; p=0·74]). INTERPRETATION: These results highlight the burden of persistent disability and dominant contribution of prematurity to long-term outcomes in children born with neonatal listeriosis. The findings support the implementation of systematic long-term screening and provision of tailored education and special needs support. FUNDING: Institut Pasteur, Inserm, French Public Health Agency, Contrat de Recherche Clinique, and Assistance Publique-Hôpitaux de Paris.

Assessment of the relationship between the MLST genetic diversity of Listeria monocytogenes and growth under selective and non-selective conditions.

Listeria monocytogenes can grow under stressful conditions and contaminate various food categories. Progresss in DNA sequencing-based identification methods, such as multi-locus sequence typing (MLST) now allow for more accurate characterization of pathogens. L. monocytogenes MLST genetic diversity is reflected by the different prevalence of the "clonal complexes" (CCs) in foods or infections. Better understanding of the growth potentials of L. monocytogenes is essential for quantitative risk assessment and efficient detection across CCs genetic diversity. Using optical density measurements taken with an automated spectrophotometer, we compared the maximal growth rate and lag phase of 39 strains from 13 different CCs and various food origins, in 3 broths mimicking stresful food conditions (8 °C, aw 0.95 and pH5) and in ISO Standard enrichment broths (Half Fraser and Fraser). This is important as growth could influence risk through pathogen multiplication in food. Besides, enrichment problems could lead to a lack of detection of some CCs. Despite small differences highlighting natural intraspecific variability, our results show that growth performances of L. monocytogenes strains under the conditions tested in selective and non-selective broth do not appear to be strongly correlated to CCs and cannot explain higher CC "virulence" or prevalence.

Fatal neonatal listeriosis following L. monocytogenes horizontal transmission highlights neonatal susceptibility to orally acquired listeriosis.

We report a case of fulminant fatal neonatal listeriosis due to horizontal transmission of Listeria monocytogenes (Lm) in a neonatal double room. Genomic analyses reveal a close genetic relationship between clinical isolates, supporting cross-contamination. Oral inoculation experiments in adult and neonatal mice show that neonates are susceptible to a low Lm inoculum and that this susceptibility results from the immaturity of the neonatal gut microbiota. Infected neonates should therefore be isolated for as long as they shed Lm in their feces to avoid horizontal transmission and its dire consequences.

Multinational Outbreak of Listeria monocytogenes Infections Linked to Enoki Mushrooms Imported from the Republic of Korea 2016-2020.

Keeping the global food supply safe necessitates international collaborations between countries. Health and regulatory agencies routinely communicate during foodborne illness outbreaks, allowing partners to share investigational evidence. A 2016-2020 outbreak of Listeria monocytogenes infections linked to imported enoki mushrooms required a multinational collaborative investigation among the United States, Canada, Australia, and France. Ultimately, this outbreak included 48 ill people, 36 in the United States and 12 in Canada, and was linked to enoki mushrooms sourced from one manufacturer located in the Republic of Korea. Epidemiologic, laboratory, and traceback evidence led to multiple regulatory actions, including extensive voluntary recalls by three firms in the United States and one firm in Canada. In the United States and Canada, the Korean manufacturer was placed on import alert while other international partners provided information about their respective investigations and advised the public not to eat the recalled enoki mushrooms. The breadth of the geographic distribution of this outbreak emphasizes the global reach of the food industry. This investigation provides a powerful example of the impact of national and international coordination of efforts to respond to foodborne illness outbreaks and protect consumers. It also demonstrates the importance of fast international data sharing and collaboration in identifying and stopping foodborne outbreaks in the global community. Additionally, it is a meaningful example of the importance of food sampling, testing, and integration of sequencing results into surveillance databases.

Genomic characterization of Listeria spp. isolated from tonsils, udder and feces of domestic dairy ruminants in Spain.

Two species of Listeria are pathogenic, Listeria monocytogenes and Listeria ivanovii. Although studies have shown that dairy ruminants shed Listeria spp. in feces, there is little information about ruminants that do not shed Listeria spp. in their feces but asymptomatically carry them in organs. We evidence that ruminants can asymptomatically carry L. ivanovii in udders and L. monocytogenes and L. ivanovii in tonsils without fecal shedding. Whole-genome sequence of L. monocytogenes and L. ivanovii contained known core genes involved in virulence and antibiotic resistance. This work highlights tonsils and udders as a Listeria intra-host site of colonization.

Genomic Surveillance of Listeria monocytogenes in Taiwan, 2014 to 2019.

Listeria monocytogenes is a life-threatening foodborne pathogen. Here, we report the genomic characterization of a nationwide dataset of 411 clinical and 82 food isolates collected in Taiwan between 2014 and 2019. The observed incidence of listeriosis increased from 0.83 to 7 cases per million population upon implementation of mandatory notification in 2018. Pregnancy-associated cases accounted for 2.8% of human listeriosis and all-cause 7-day mortality was of 11.9% in nonmaternal-neonatal listeriosis. L. monocytogenes was isolated from 90% of raw pork and 34% of chicken products collected in supermarkets. Sublineages SL87, SL5, and SL378 accounted for the majority (65%) of clinical cases. SL87 and SL378 were also predominant (57%) in food products. Five cgMLST clusters accounted for 57% clinical cases, suggesting unnoticed outbreaks spanning up to 6 years. Mandatory notification allowed identifying the magnitude of listeriosis in Taiwan. Continuous real-time genomic surveillance will allow reducing contaminating sources and disease burden. IMPORTANCE Understanding the phylogenetic relationship between clinical and food isolates is important to identify the transmission routes of foodborne diseases. Here, we performed a nationwide study between 2014 and 2019 of both clinical and food Listeria monocytogenes isolates and sequenced their genomes. We show a 9-fold increase in listeriosis reporting upon implementation of mandatory notification. We found that sublineages SL87 and SL378 predominated among both clinical (50%) and food (57%) isolates, and identified five cgMLST clusters accounting for 57% of clinical cases, suggestive of potential protracted sources of contamination over up to 6 years in Taiwan. These findings highlight that mandatory declaration is critical in identifying the burden of listeriosis, and the importance of genome sequencing for a detailed characterization of the pathogenic L. monocytogenes genotypes circulating in Asia.

Listeria ilorinensis sp. nov., isolated from cow milk cheese in Nigeria.

During microbial assessment of cow milk cheese products in the city of Ilorin, Nigeria, a Listeria-like isolate was detected that could not be assigned to any known species. Whole-genome sequence analyses against all currently known 26 Listeria species confirmed that this isolate constitutes a new taxon within the genus Listeria, with highest similarity to Listeria costaricensis (average nucleotide identity blast of 82.66%, in silico DNA-DNA hybridization of 28.3%). Phenotypically, it differs from L. costaricensis by the inability to ferment sucrose, l-fucose and starch. The absence of haemolysis and Listeria pathogenic islands suggest that this novel species is not pathogenic for humans and animals. The name Listeria ilorinensis sp. nov. is proposed, with the type strain CLIP 2019/01311T (=CIP 111875T=DSM 111566T).

Listeria-Associated Lymphadenitis: A Series of 11 Consecutive Cases and Review of the Literature.

We studied 11 cases of culture-proven Listeria-associated lymphadenitis reported to the French National Reference Center for Listeria from 1994 to 2019 and 8 additional published cases. Listeria-associated lymphadenitis is rare, but it is associated with a mortality as high as for invasive listeriosis, and it is frequently diagnosed with concomitant neoplasia.

Neonatal Listeriosis Presentation and Outcome: A Prospective Study of 189 Cases.

BACKGROUND: Listeriosis is caused by the foodborne pathogen Listeria monocytogenes. It can present as a maternal-neonatal infection. We implemented a nationwide prospective cohort and analyzed the features of neonatal listeriosis. METHODS: We studied all neonates born alive from mothers with microbiologically proven maternal-neonatal listeriosis enrolled from November 2009 to December 2017. We analyzed presentation, neonatal outcome at discharge, and predictors of severe presentation and outcome. RESULTS: We studied 189 infants; 133 of 189 (70%) had abnormal clinical status at birth, including acute respiratory distress in 106 of 189 (56%). There were 132 of 189 (70%) infants who developed early-onset listeriosis and 12 of 189 (6%) who developed late-onset listeriosis; all presented with acute meningitis. There were 17 of 189 (9%) infants who had major adverse outcomes: 3%, (5 of 189) death; 6% (12 of 189), severe brain injury; and 2% (3 of 189), severe bronchopulmonary dysplasia. Fifteen of 17 infants were born <34 weeks of gestation (P < .0001 vs infants born ≥34 weeks of gestation). Maternal antimicrobial treatment ≥1 day before delivery was associated with a significant decrease in presentation severity for the infant, resulting in significantly fewer inotropic drugs, fluid resuscitation, and mechanical ventilation requirement (odds ratio, 0.23; 95% confidence interval, 0.09-0.51; P < .0001). CONCLUSIONS: Antenatal maternal antimicrobial treatment is associated with reduced neonatal listeriosis severity, justifying the prescription of preemptive maternal antimicrobial therapy when maternal-fetal listeriosis is suspected. Neonatal outcome is better than reported earlier, and its major determinant is gestational age at birth. CLINICAL TRIALS REGISTRATION: NCT01520597.

Emergence and global spread of Listeria monocytogenes main clinical clonal complex.

The bacterial foodborne pathogen Listeria monocytogenes clonal complex 1 (Lm-CC1) is the most prevalent clonal group associated with human listeriosis and is strongly associated with cattle and dairy products. Here, we analyze 2021 isolates collected from 40 countries, covering Lm-CC1 first isolation to present days, to define its evolutionary history and population dynamics. We show that Lm-CC1 spread worldwide from North America following the Industrial Revolution through two waves of expansion, coinciding with the transatlantic livestock trade in the second half of the 19th century and the rapid growth of cattle farming and food industrialization in the 20th century. In sharp contrast to its global spread over the past century, transmission chains are now mostly local, with limited inter- and intra-country spread. This study provides an unprecedented insight into L. monocytogenes phylogeography and population dynamics and highlights the importance of genome analyses for a better control of pathogen transmission.

Ruminant-associated Listeria monocytogenes isolates belong preferentially to dairy-associated hypervirulent clones: a longitudinal study in 19 farms.

Studies have shown that ruminants constitute reservoirs of Listeria monocytogenes, but little is known about the epidemiology and genetic diversity of this pathogen within farms. Here we conducted a large-scale longitudinal study to monitor Listeria spp. in 19 dairy farms during three consecutive seasons (N = 3251 samples). L. innocua was the most prevalent species, followed by L. monocytogenes. Listeria monocytogenes was detected in 52.6% of farms and more frequently in cattle (4.1%) and sheep (4.5%) than in goat farms (0.2%). Lineage I accounted for 69% of L. monocytogenes isolates. Among animal samples, the most prevalent sublineages (SL) and clonal complexes (CC) were SL1/CC1, SL219/CC4, SL26/CC26 and SL87/CC87, whereas SL666/CC666 was most prevalent in environmental samples. Sixty-one different L. monocytogenes cgMLST types were found, 28% common to different animals and/or surfaces within the same farm and 21% previously reported elsewhere in the context of food and human surveillance. Listeria monocytogenes prevalence was not affected by farm hygiene but by season: higher prevalence was observed during winter in cattle, and during winter and spring in sheep farms. Cows in their second lactation had a higher probability of L. monocytogenes faecal shedding. This study highlights dairy farms as a reservoir for hypervirulent L. monocytogenes.

Listeria spp. Isolated from Tonsils of Wild Deer and Boars: Genomic Characterization.

Listeria monocytogenes is a major human and animal foodborne pathogen. However, data from environmental reservoirs remain scarce. Here, we used whole-genome sequencing to characterize Listeria species isolates recovered over 1 year from wild animals in their natural habitats in Spain. Three different Listeria spp. (L. monocytogenes [n = 19], Listeria ivanovii subsp. londoniensis [n = 4], and Listeria innocua [n = 3]) were detected in 23 animal tonsils (9 deer, 14 wild boars) and 2 feeding troughs. No Listeria species was detected in feces. L. monocytogenes was detected in tonsils of 44.4% (8 out of 18) of deer and 40.7% (11 out of 27) of wild boars. L. monocytogenes isolates belonged to 3 different core genome multilocus sequence typing (cgMLST) types (CTs) of 3 distinct sublineages (SL1, SL387, and SL155) from lineages I and II. While cgMLST type L1-SL1-ST1-CT5279 (IVb; clonal complex 1 [CC1]) occurred only in one animal, types L1-SL387-ST388-CT5239 (IVb; CC388) and L2-SL155-ST155-CT1170 (IIa; CC155) were retrieved from multiple animals. In addition, L1-SL387-ST388-CT5239 (IVb; CC388) isolates were collected 1 year apart, revealing their long-term occurrence within the animal population and/or environmental reservoir. The presence of identical L. monocytogenes strains in deer and wild boars suggests contamination from a common food or environmental source, although interhost transmission cannot be excluded. Pathogenicity islands LIPI-1, LIPI-3, and LIPI-4 were present in 100%, 5%, and 79% of the L. monocytogenes isolates, respectively, and all L. monocytogenes lineage II isolates (n = 3) carried SSI-1 stress islands. This study highlights the need for monitoring L. monocytogenes environmental contamination and the importance of tonsils as a possible L. monocytogenes intrahost reservoir.IMPORTANCEListeria monocytogenes is a foodborne bacterial pathogen responsible for listeriosis. Whole-genome sequencing has been extensively used in public health and food industries to characterize circulating Listeria isolates, but genomic data on isolates occurring in natural environments and wild animals are still scarce. Here, we show that wild animals carry pathogenic Listeria and that the same genotypes can be found at different time points in different host species. This work highlights the need of Listeria species monitoring of environmental contamination and the importance of tonsils as a possible L. monocytogenes intrahost reservoir.

Listeria valentina sp. nov., isolated from a water trough and the faeces of healthy sheep.

In the context of a study on the occurrence of Listeria species in an animal farm environment in Valencia, Spain, six Listeria-like isolates could not be assigned to any known species. Phylogenetic analysis based on the 16S rRNA gene and on 231 Listeria core genes grouped these isolates in a monophyletic clade within the genus Listeria, with highest similarity to Listeria thailandensis. Whole-genome sequence analyses based on in silico DNA-DNA hybridization, the average nucleotide blast and the pairwise amino acid identities against all currently known Listeria species confirmed that these isolates constituted a new taxon within the genus Listeria. Phenotypically, these isolates differed from other Listeria species mainly by the production of acid from inositol, the absence of acidification in presence of methyl α-d-glucoside, and the absence of α-mannosidase and nitrate reductase activities. The name Listeria valentina sp. nov. is proposed for this novel species, and the type strain is CLIP 2019/00642T (=CIP 111799T=DSM 110544T).

Genomic Characterization of Listeria monocytogenes Isolated From Ready-to-Eat Meat and Meat Processing Environments in Poland.

Listeria monocytogenes is one of the major foodborne pathogens. Isolates of PCR-serogroups IIb (n = 17) and IVb (n = 31) recovered from food (n = 33) and food processing environment (n = 15) in Poland were characterized using whole genome sequencing. Most isolates belonged to Multi-Locus Sequence Type (MLST) ST2 (31.3%) and ST5 (22.9%). Core genome MLST (cgMLST) analysis classified isolates into seven sublineages (SL) and 25 different cgMLST types (CT). Consistent with the MLST results, most sublineages were SL2 and SL5. Eleven isolates harbored aacA4 encoding resistance to aminoglycosides, three isolates harbored emrC (n = 3) and one brcABC (n = 1) encoding tolerance to benzalkonium chloride. Isolates belonging to SL5 CT2323 carried a so far unreported inlB allele with a deletion of 141 nucleotides encoding the ß-repeat sheet and partially the GW1 domain of InlB. Comparison with publicly available genome sequences from L. monocytogenes isolated from human listeriosis cases in Poland from 2004 to 2013 revealed five common CTs, suggesting a possible epidemiological link with these strains. The present study contributes to characterize the diversity of L. monocytogenes in ready-to-eat (RTE) meat and meat processing environments in Poland and unravels previously unnoticed links with clinical cases in Europe.