Search Results (464)

Shiga toxin-producing Escherichia coli (STEC) has emerged globally as a critical enteric foodborne zoonotic pathogen with significant public health implications. This study aimed to isolate and characterize STEC strains from Rattus spp. and layer chickens, specifically evaluating their antimicrobial resistance (AMR) profiles and the prevalence of extended-spectrum β-lactamase (ESBL)-producing isolates. A total of 274 fecal samples were collected from Rattus spp. (n = 154) and layer chickens (n = 120). Isolates were characterized using standard microbiological techniques, PCR amplification of specific genes (including uidA and stx), and antimicrobial susceptibility testing via the disk diffusion method. Results: Of the 248 presumptive E. coli isolates, 237 (95.5%) were confirmed via uidA gene amplification. Fifty-eight isolates were confirmed as STEC, including key O-serogroups (O103, O111, O26, and O157). Resistance was most prevalent against colistin (39.6%) and streptomycin (20.6%), with 8.6% of isolates exhibiting multidrug resistance (MDR). Additionally, 19 isolates showed ESBL-producing phenotypes, and resistance genes for colistin, phenicols, aminoglycosides, and carbapenems were detected. The presence of STEC and MDR strains in both rodents and poultry highlights a high pathogenic potential and a serious zoonotic risk to public health, necessitating enhanced surveillance. Full article

Shigella spp., and Escherichia coli exhibit notable genomic and phenotypic similarities, including serologically and genetically related somatic antigens. For example, the relationship among pathogenic strains E. coli 64474, O179, O188, and S. boydii O16 suggests a shared clonal origin. To evaluate their genomic proximity, a comparative genomics study was conducted using whole-genome sequencing. Comparative genomics involved rfb gene cluster regions and whole-genome comparisons. Phylogenomic inferences were performed using the virtual genome fingerprint (VGF) method with bootstrap support. The results revealed a high degree of genomic similarity and a close evolutionary relationship among E. coli strains, which also demonstrated genetic associations with clinically relevant pathotypes through the presence of virulence genes. Furthermore, serogroups 64474, O188, and S. boydii O16 exhibited close genetic relationships, suggesting that serotype 64474 could represent a novel serogroup, although its similarity to O188 indicates the influence of divergent factors. These findings support the hypothesis that these E. coli strains originated from a common clonal lineage, enhancing our understanding of serogroup diversity and the evolutionary dynamics within enteric pathogens. Full article

Legionnaires’ disease is a rare cause of atypical pneumonia associated with a high mortality rate among untreated patients. In Romania, the disease has historically been underreported due to insufficient surveillance and limited diagnostic capacity. The aim of this study was to describe the characteristics of Legionnaires’ disease cases admitted to a specialized infectious disease hospital between 2023 and 2024, with a particular focus on a cluster associated with travel to a spa resort. Most cases included in our study (31/36) were confirmed by urinary antigen testing, while one case was confirmed by a significant increase in the level of specific antibodies against Legionella pneumophila serogroup 1 in paired serum samples. The most frequently reported symptom was fever (28/32), followed by chills (24/32). Among the 32 confirmed cases, 3 patients died. Two cases were identified as part of a family cluster involving a father and son who had undergone physiotherapy at a balneary resort. Both patients presented with fever and gastrointestinal symptoms, and radiological investigations confirmed mixed pneumonia associated with an intense inflammatory syndrome. In the father’s case, hepatic involvement and interstitial nephritis were also identified. Early diagnosis based on epidemiological data, clinical predictive scores, and laboratory investigations would allow timely administration of targeted antibiotic therapy and may contribute to reduced mortality. Full article

Pasteurella multocida (P. multocida) is a significant pathogenic bacterium that causes serious disease and death in the yaks of the Tibetan Plateau, and the existing inactivated vaccines are limited by low protection and reactogenicity. Outer membrane vesicles (OMVs) derived from a yak-origin serogroup B P. multocida isolate were evaluated as a potential vaccine candidate in the present study. The purified OMVs were characterized by transmission electron microscopy and nanoparticle tracking analysis, which demonstrated the presence of typical bilayer vesicles ranging from 20 to 300 nm in diameter. Proteomic profiling revealed 1213 proteins, with many of them being immunologically relevant outer membrane-associated proteins like OmpA, OmpH, Omp16, OmpW, TbpA and PlpP. The functional enrichment analysis showed that these proteins were linked to translation, membrane structure, transport, metabolism, and pathways of adaptation of bacteria. In vitro OMVs were effectively taken up by RAW264.7 macrophages and stimulated robust expression of inflammatory mediators, such as TNF-α, IL-1β, IL-6, iNOS and IL-10, which is indicative of strong innate immunostimulatory capacity. OMV immunization induced significant antigen specific humoral responses in mice and yaks in vivo. In mice, intramuscular immunization was effective in giving full protection against P. multocida challenge but not intranasal immunization. Histopathology also indicated less tissue damage in vaccinated animals, especially in the lung and liver. These findings, taken together, prove that yak-derived P. multocida OMVs have high immunogenicity and protection capabilities, which show their potential as a next-generation vaccine platform to tackle P. multocida infection. Full article

Listeria monocytogenes remains a major foodborne pathogen associated with ready-to-eat (RTE) products, including smoked fish. This study investigated the occurrence, molecular characteristics, virulence gene profiles, and antimicrobial susceptibility of L. monocytogenes isolated from retail smoked fish in Poland. A total of 46 samples (cold- and hot-smoked products) collected from 15 producers and five retail chains were analyzed using ISO 11290-1:2017 for qualitative detection and ISO 11290-2:2017 for enumeration. Listeria spp. were detected in 5/46 samples (10.9%), including 4 isolates confirmed as L. monocytogenes (8.7%). All positive samples originated from cold-smoked salmon, with a prevalence of 4/13 (30.8%) in this product category. The quantitative analysis indicated that contamination levels in all positive samples were below 100 CFU/g. Molecular serogrouping and multiplex PCR demonstrated the presence of key virulence-associated genes, including hlyA, prfA, plcB, and actA, consistent with potentially pathogenic profiles. Pulsed-field gel electrophoresis (PFGE) revealed clustering of isolates, indicating genetic relatedness among strains obtained from different retail sources. Antimicrobial susceptibility testing using the MICRONAUT system showed that all L. monocytogenes isolates were susceptible to first-line therapeutic agents, including ampicillin and penicillin, according to EUCAST/CLSI criteria. Although contamination levels were low and isolates remained susceptible to clinically relevant antimicrobials, the detection of virulence-associated strains in RTE smoked fish highlights the need for continuous monitoring and strict hygienic control in the production and retail chain. These findings contribute to regional surveillance data on L. monocytogenes in smoked fish products in Poland. Full article

This study evaluated the performance of Fourier-transform infrared (FTIR) spectroscopy for identifying spectral signatures associated with two key traits of Listeria monocytogenes: serogroup classification and biofilm-forming capacity. A total of 100 strains, previously serogrouped by PCR and categorized as high, intermediate, or low biofilm producers, were analyzed. Whole-genome sequencing was performed, and comparative genomics was conducted at core-genome, pangenome, and whole-genome (k-mer) levels to determine which genomic representation best reflected the phenotypes. Strains were typed using Fourier-Transform Infrared (FTIR Biotyper^® system from Bruker Daltonics GmbH and Co., Bremen, Germany) with five technical replicates. Spectral data from the polysaccharide region (1300–800 cm⁻¹) were extracted and used to train twelve statistical models within a machine learning pipeline combined with cross-validation to predict four serogroups and three biofilm clusters from 501 spectral variables. Genomic analyses showed strong concordance between population structure and serogroup, whereas biofilm formation displayed only weak genomic association, explaining less than 0.1% of genomic variance (PERMANOVA R² ≤ 0.001). Penalized discriminant analysis achieved the highest performance for serogroup prediction (overall accuracy 97.2%), while the k-nearest neighbor model performed best for biofilm prediction (74.8%). Two dedicated R Shiny applications were developed to facilitate model use. Overall, FTIR spectroscopy coupled with machine learning can provide a rapid and cost-effective alternative to PCR, genomic analyses, and in vitro assays for phenotypic trait prediction. Full article

Background/Objectives: Meningococcal disease is primarily caused by serogroups A, B, C, W, and Y. Current US vaccination recommendations include routine serogroup A/C/W/Y (MenACWY) vaccination (ages 11–12 and 16 years) and a two-dose, 0-, 6-month MenB vaccination series (age 16–23 years) based on shared clinical decision-making. Administration of the first-in-class Pfizer pentavalent MenABCWY vaccine (Penbraya^TM), which received US licensure in 2023 as a two-dose, 0-, 6-month series, is endorsed when the MenACWY and MenB vaccines are recommended at the same visit. This study evaluated the immunogenicity and safety of two extended two-dose schedules of MenABCWY in healthy adolescents. Methods: In this observer-blinded, phase 2b study (ClinicalTrials.gov, NCT04440176; 19 June 2020), 309 healthy 11- to 14-year-olds were randomized 1:1 to receive a 0-, 36-month or 0-, 12-month Pfizer MenABCWY schedule, which more closely aligns with current US MenACWY vaccination recommendations. Endpoints included serum bactericidal assay using human complement seroprotection rates (titers ≥ 1:8 or ≥1:16, depending on strain), seroresponse rates (≥4-fold increase from baseline titer), and geometric mean titers (GMTs). Safety was also assessed. Results: One month after the second Pfizer MenABCWY dose, serogroup A/B/C/W/Y seroprotection rates were 100% for the 0-, 36-month schedule and 96.6–100% for the 0-, 12-month schedule; seroresponse rates were 100% and 92.9–100%, respectively. GMTs generally trended higher with the 0-, 36-month schedule. Seroprotection rates through 24 months after the second dose of the 0-, 12-month schedule were 44.0–75.0% for serogroup B and 88.9–100% for serogroup A/C/W/Y). No safety issues were identified. Conclusions: These data support Pfizer MenABCWY dosing flexibility and utility within the current or possible future US meningococcal vaccination framework. Full article

Phage-encoded Shiga toxin (Stx) released by Shiga toxin-producing E. coli (STEC) can kill multiple eukaryotic bacterial predators, including Acanthamoeba castellanii, Tetrahymena thermophila and Caenorhabditis elegans. However, the impact of Stx type, Stx amount, and the serogroup of the E. coli on the effectiveness of this exotoxin are poorly understood. These factors impact the severity of Stx-mediated disease in humans and therefore, by studying their role in modulating predator–prey interactions, we may gain insight into how these virulence factors evolved to contribute to human pathogenicity. Herein, we investigated the effects of these factors on predator killing by measuring the efficiency with which five different hemolytic uremic syndrome (HUS)-causing STEC strains consume and/or kill A. castellanii and C. elegans. These strains express various combinations of Stx types and amounts and O-antigens. We found that variations in Stx types and amounts significantly affect the ability of a given bacterial strain to kill predator A. castellanii and C. elegans, with higher Stx1 titers (HUSEC 31 vs. 19) and the presence of Stx2 alone (HUSEC 20) correlating with significantly greater predator killing. These attributes also affect STEC pathogenicity in humans, suggesting that ecological selective pressures for anti-predator defense inadvertently drive the evolution of strains with higher virulence potential in humans. Full article

Legionella species are ubiquitous bacteria found worldwide in water, moist environments, soils, and compost. Infection occurs through the inhalation of aerosols, leading to either Pontiac fever or Legionnaires’ disease (LD). Current routine diagnostics typically combine culture-based isolation with Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) for species identification and the Latex Agglutination Test (LAT) for serotyping. However, this workflow is fragmented: MALDI-TOF MS lacks serogroup-specific resolution, while LAT relies on subjective visual interpretation. Therefore, this study evaluated Fourier-transform infrared spectroscopy (FT-IR) as a rapid, high-resolution typing method for Legionella isolates to assess its potential as a single-step diagnostic tool. A total of 200 clinical and environmental Legionella isolates were analyzed using FT-IR, including L. pneumophila serogroups (SG) 1–15 and various non-pneumophila species. Spectral data were analyzed using Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA). While MALDI-TOF MS provided accurate species identification, FT-IR spectroscopy demonstrated superior typing capabilities by successfully distinguishing L. pneumophila SG 1 distinct from the SG 2–15 complex and allowing for clear discrimination of most non-pneumophila species. Additionally, FT-IR resolved isolates that showed ambiguous or non-reactive results in LAT. These findings demonstrate that FT-IR overcomes the serotyping limitations of MALDI-TOF MS and offers a more objective, cost-efficient extension to the current multi-step routine, potentially closing the diagnostic gap between simple species identification and deep strain characterization. Full article

Background: Climate change represents a major global health challenge, with rising temperatures and altered precipitation patterns influencing the spread of infectious diseases. This study investigated the association between climatic factors (average temperature and precipitation) and the monthly proportion of laboratory-confirmed Legionella pneumophila serogroup 1 and West Nile Virus infections among clinically suspected patients in a large teaching hospital in Northern Italy. Methods: We retrospectively analyzed data from 2021 to 2024. The primary outcome was the monthly proportion of positive tests (standardized per 1000 clinically suspected patients) for Legionella pneumophila serogroup 1 (urinary antigen) and West Nile Virus (serology). Associations with climatic variables were assessed using linear and multivariate regression models, as well as Generalized Additive Models (GAMs). Seasonal effects were evaluated through ANOVA. Results: For Legionella pneumophila, precipitation was not significantly associated with the proportion of positive tests (p = 0.1438; R² = 0.049). In contrast, average temperature was a significant predictor: each 1 °C increase was associated with +0.52 positive cases per 1000 tested patients (p = 0.000283; R² = 0.267). Multivariate models confirmed temperature as the dominant factor. For West Nile Virus, precipitation showed no meaningful effect (p = 0.914). However, average temperature demonstrated a significant positive association with the proportion of positive cases (p = 0.00293; coefficient = 9.33), with seasonal analysis highlighting a marked summer peak (mean = 399.68 positive cases per 1000 tested; p = 0.00653). Conclusions: Our findings underline the predominant role of temperature over precipitation in driving the burden of both Legionella pneumophila and West Nile Virus infections among hospitalized patients. These results strengthen the evidence that the life cycles of these pathogens are tightly climate-dependent. Developing effective adaptation strategies is essential to mitigate climate-related health risks. Full article

Background: Invasive meningococcal disease (IMD) caused by Neisseria meningitidis remains a major public health concern due to its severity, lethality, and long-term sequelae. To address the rise in serogroups W and Y in Spain, the Community of Madrid implemented a catch-up campaign in 2019–2021, targeting adolescents (ages 13–18) alongside routine tetravalent meningococcus vaccine (MenACWY) at age 12. This study evaluated MenACWY catch-up vaccination uptake in routine practice by describing vaccine coverage, temporal trends, and associated factors in adolescents born between 2001 and 2006. Methods: A population-based cross-sectional study was conducted using data from the Community of Madrid’s vaccination registry (SISPAL Vacunas). Vaccination coverage was calculated for adolescents with at least one recorded MenACWY dose from age 10 onwards. Temporal trends were analyzed by birth cohort and calendar time, and multivariable logistic regression models were used to identify factors associated with vaccination uptake. Results: Among 424,059 adolescents, overall vaccination coverage by December 2021 was 63.8%, ranging from 54.4% to 78.2% across birth cohorts. Coverage was highest in the 2006 cohort, likely due to co-administration with the tetanus and diphtheria (Td) booster. A slightly higher uptake was observed among females and adolescents with chronic conditions, while foreign-born adolescents consistently showed lower coverage. COVID-19 disruptions led to temporal variability, with sharp declines during lockdowns and partial recoveries thereafter, with persistent sociodemographic differences in uptake. Conclusions: By December 2021, coverage was incomplete, with marked variability across birth cohorts. Higher uptake was observed when vaccination was integrated into routine visits, while persistent sociodemographic disparities remained evident. These observational findings are consistent with the programmatic value of combined catch-up and routine strategies and the need for targeted actions to ensure equitable MenACWY coverage. Full article

Invasive meningococcal disease (IMD) is classically associated with meningitis and septic shock, but an increasing proportion of cases present with atypical, extra-meningeal manifestations. Following the COVID-19 pandemic, major epidemiological shifts have occurred in France, including a rebound in IMD incidence and changes in circulating serogroups and clonal complexes. We conducted a nationwide retrospective study including all laboratory-confirmed IMD cases analysed by the French National Reference Centre between July 2014 and June 2025. Clinical presentations were coded as non-exclusive entities. Associations with age, serogroup, clonal complex, antimicrobial susceptibility and early mortality (≤72 h) were assessed using descriptive analyses and multivariable logistic regression models. Among 4328 IMD cases, sepsis/shock (61.1%) and meningeal involvement (54.9%) predominated, while atypical forms were frequent, including bacteraemic pneumonia (7.7%), abdominal presentations (8.0%) and arthritis (6.0%). Bacteraemic pneumonia was strongly associated with older age and serogroups W and Y, whereas abdominal forms predominated in adolescents and young adults and were independently associated with serogroups W and Y and clonal complex (cc) cc11. Abdominal presentations were independently associated with early mortality (adjusted odds ratio [aOR] 2.40) but not meningococcal pneumonia. Abdominal presentations were associated with serogroup W (aOR 2.27; 95% CI 1.35–3.83) and serogroup Y (aOR 2.92; 95% CI 1.79–4.75) and with cc11 (aOR 1.77; 95% CI 1.07–2.94). In contrast, cc23 was associated with lower odds of abdominal involvement (aOR 0.42; 95% CI 0.25–0.70). Overall, atypical presentations now represent a substantial proportion of IMD in France and are strongly shaped by age and meningococcal lineage. These findings highlight diagnostic challenges, prognostic heterogeneity and the need for continued integrated clinical, microbiological and genomic surveillance in the context of evolving vaccination strategies. Full article

Leptospirosis is an important zoonosis that can present as a self-limited influenza-like illness or progress to severe, including life-threatening multiorgan dysfunction. We report the epidemiology, clinical profile, and correlates of severity among adults hospitalized patients with leptospirosis diagnosed in central Romania over a period of 17 years. We conducted a retrospective, single-center cohort study of adults admitted between 1 January 2008 and 1 December 2025 with laboratory-confirmed leptospirosis. Confirmation was based on positive anti-Leptospira IgM serology, with repeat testing when the initial result was equivocal and confirmation with a microscopic agglutination test. We extracted demographic, exposure, clinical, laboratory, treatment, and outcome data from medical records. The modified Faine score was also calculated using admission data. Sixty-four patients were included in this analysis, of which 53 (82.8%) were male patients. Admissions peaked in 2023–2025 (34/64, 53.1%) and in the August–September months. Reported exposures were predominantly peri-domestic (46.9%), followed by rural/animal-related occupations (20.3%) and freshwater contact (17.2%). Severe disease occurred in 26/64 (40.6%), was more frequent in men (p = 0.021), and was more common pre-pandemic than during/after the pandemic (p < 0.001). Severe cases were associated with oliguria/anuria, hematuria, and jaundice, alongside higher urea/creatinine and bilirubin, lower hemoglobin and lymphocyte percentages, and a longer hospitalization period. One in-hospital death occurred (1.6%). Serogroup identification was available for 10 patients (15.6%) (pre-pandemic only). The mean modified Faine score was 27.5 ± 6.0. In this temperate-region cohort study, hospitalized leptospirosis showed a marked male predominance, a late-summer peak, and a substantial burden of severe disease. Early renal and hepatobiliary manifestations with concordant laboratory abnormalities may support timely risk stratification and escalation of care, while expanded molecular diagnostics and systematic typing are needed to clarify temporal trends and guide prevention. Full article

African swine fever (ASF) continues to spread, threatening the global swine industry and endangered swine species. Sri Lanka is a tropical island situated south of India in the Indian Ocean. Here, we report the first detection of ASF in Sri Lanka. In September 2024, increased pig mortality was reported across the country, with initial confirmation of porcine reproductive and respiratory syndrome (PRRS). Despite vaccination for PRRS, the mortalities continued to increase and therefore, tissue samples collected from dead pigs were subjected to ASF real-time PCR. ASFV genomic material was detected in most of the samples. The real-time PCR-positive samples were then subjected to genotyping by partial genome sequencing. All p72 and p54 sequences were found to be aligned with ASFV genotype II viruses, and CD2v sequences were found to be aligned with ASFV serogroup 8 viruses. The real-time PCR-positive samples were inoculated onto primary porcine leukocytes for virus isolation, and a selected number of tissues collected from dead pigs were subjected to histopathology. Histopathological studies revealed widespread loss of lymphocytes together with inflammation and extensive staining of ASFV antigens in tissue samples. Hemadsorption (HAD)-positive isolates were obtained from seven clinical samples, and three of them were subjected to whole-genome sequencing. Phylogeographic analysis of the whole-genome sequences showed that the virus is closely related to ASFV strains circulating in China and Hong Kong. Full article

Listeria monocytogenes is a high-risk pathogenic bacterium associated with ready-to-eat foods and poses a potential threat to consumer health. This study aimed to investigate the prevalence, characterization and genetic diversity of L. monocytogenes in ready-to-eat raw salmon and trout products obtained from physical stores and online stores in China. Out of 150 samples analyzed, 23 (15.3%) were positive for L. monocytogenes. Among these positive samples, three (12%) were from Japanese restaurants, four (16%) from farmers markets, one (2.9%) from large supermarkets and fifteen (30%) from e-commerce platforms, and only one sample showed a contamination level exceeding 100 most probable number (MPN)/g. The isolates from positive samples demonstrated a concrete public health risk through several findings: twenty-three L. monocytogenes exhibited varying degrees of cytotoxicity, ranging from 7.6% to 71.8%. Compared with the reference strain ATCC 19115, five of these isolates were highly cytotoxic, a result that was validated by mouse survival rate experiment, which also confirmed their high virulence at tested dose. All isolates were resistant to cefuroxime sodium, ceftriaxone, cefepime and nalidixic acid, and 13% showed resistance to sulphamethoxazole-trimethoprim. Three serogroups were identified, with serogroup Ⅰ.1 (1/2a, 3a) being the most prevalent (65.2%). These isolates were grouped into eight sequence types, with ST8 (34.8%) and ST87 (30.4%) dominating. All isolates carried virulence genes associated with LIPI-1 andmultiple internalin genes (inlA, inlB, inlJ and inlK), confirming their potential pathogenicity. Additionally, the isolates harbored antimicrobial resistance genes lin and FosX. The five highly virulent isolates exhibited the highest genetic similarity to J2-031 (GCA_000438645.1) and C1-387 (GCA_000438605.1). The results provided valuable information for Chinese regulatory authorities to strengthen the risk monitoring of L. monocytogenes in ready-to-eat raw salmon and trout products. Full article