Search Results (254)

Background: Rapid etiological diagnosis of bacterial meningitis is crucial in children, as delays can lead to neurological sequelae. The BioFire FilmArray Meningitis/Encephalitis (ME) panel is widely used on cerebrospinal fluid (CSF), but its target spectrum may miss healthcare-associated or multidrug-resistant pathogens. We evaluated the diagnostic performance and stewardship-oriented clinical impact of off-label BioFire FilmArray Blood Culture Identification 2 (BCID2) testing on CSF from pediatric patients with suspected bacterial CNS infection and negative ME results. Methods: We retrospectively analyzed CSF samples collected between January 2023 and March 2025 at a tertiary pediatric hospital. In ME-negative cases with persistent suspicion and abnormal CSF parameters, BCID2 was performed off-label on residual CSF aliquots after routine testing, without additional sampling. We assessed pathogen detection, agreement with culture, resistance-gene identification, and documented stewardship actions. Results: Among 76 ME-negative CSF samples tested with BCID2, 23 (30.3%) were positive, all involving organisms not included in the ME panel. BCID2 was concordant with culture in 19/23 cases (82.6%); 4/23 (17.4%) were BCID2-positive/culture-negative, consistent with reduced culture sensitivity in frequently pretreated cases. Resistance genes (VIM, vanA/B, CTX-M) were detected in 30.4% of BCID2-positive samples. Overall agreement with culture was 94.7% (PPA 100%, NPA 93.0%). Escalation was documented in 13/23 episodes (56.5%), discontinuation in 2/23 (8.7%), and confirmation in 9/23 (39.1%), with no de-escalation events; clinical outcomes were not systematically available. Conclusions: In selected ME-negative pediatric cases with abnormal CSF profiles, BCID2 testing on residual CSF provided rapid, clinically meaningful microbiological information that may support antimicrobial optimization. Full article

Background/Objectives: Extraintestinal pathogenic Escherichia coli (ExPEC) is a major pathogen that causes septicemia, meningitis, and polyserositis in pigs. The increasing prevalence of antimicrobial resistance and the diverse serotypes of ExPEC highlight the urgent need for broadly protective vaccines. Methods and Results: In this study, an OmpC epitope vaccine based on the T4 phage display system was developed and evaluated. Two B-cell epitopes (OmpC-1 and OmpC-2) were identified by bioinformatic analysis and displayed on recombinant T4 phages. Immunization induced strong antigen-specific IgG responses, with the OmpC-1-T4 group showing significantly higher antibody titers than the OmpC protein group. In the O11 serotype PCN033 challenge model, survival rates reached 100% in the OmpC-1-T4 group, 60% in the OmpC-2-T4 group, and approximately 80% in the OmpC protein group. In the O18 serotype 2103 challenge model, both recombinant phage groups had survival rates of approximately 60%, whereas all the mice in the OmpC protein group died within three days. OmpC-1-T4 immunization also significantly reduced bacterial loads in lung and brain tissues after PCN033 infection and decreased TNF-α and IL-6 expression in lung tissues, accompanied by reduced inflammatory infiltration and tissue damage. Conclusions: Overall, the T4 phage-displayed OmpC epitope vaccine induced strong humoral immunity and provided protection against different ExPEC serotypes. Among the candidates, OmpC-1-T4 showed superior immune protection, bacterial clearance, and inflammation control, supporting its potential as a vaccine candidate against porcine ExPEC infection. Full article

Neonatal meningitis-associated Escherichia coli (NMEC) is a formidable pathogen in veterinary medicine. The emergence of atypical, multidrug-resistant (MDR) variants complicates disease control. An Escherichia coli (E. coli) strain was isolated from the brain tissue of a deceased calf with acute meningitis. Comprehensive characterizations were performed, including whole-genome sequencing (WGS), multi-locus sequence typing (MLST), antimicrobial susceptibility testing (AST), murine pathogenicity assays, and RT-qPCR evaluation of neuroinflammatory cytokines. Results: The isolate (O18ab:H14) was identified as a capsule-deficient NMEC strain belonging to phylogroup A and sequence type ST1434. WGS showed that the genome size of this strain is 5.1 Mb, containing 73 strictly defined antimicrobial resistance genes and 202 virulence factors. These may be involved in the compensatory mechanism for capsule deficiency, and further functional verification is required. Phenotypically, it exhibited a robust MDR profile. In the murine model, the strain demonstrated high lethality, and induced severe multi-organ lesions characteristic of both meningitis and systemic sepsis. While intraperitoneal injection bypasses natural colonization routes, the brain-specific bacterial persistence and neuronal pathology imply neurotropic potential. Furthermore, RT-qPCR confirmed a severe neuroinflammatory response, marked by the significant upregulation of IL-1β, IL-6, and TNF-α in the infected brains. This study characterizes a novel, highly virulent, and MDR capsule-deficient NMEC/SEPEC hybrid strain. The findings emphasize the urgent need for continuous genomic surveillance of atypical E. coli pathotypes in livestock. Full article

Background/Objectives: Healthcare-associated ventriculitis and meningitis (HAVM) is a life-threatening complication of neurosurgical procedures. Conventional cerebrospinal fluid (CSF) indices cannot reliably distinguish bacterial infection from sterile postoperative inflammation, and cultures are frequently delayed or negative. We conducted the first systematic review and meta-analysis to determine the pooled diagnostic accuracy of CSF heparin-binding protein (HBP) for HAVM and to establish clinically actionable decision thresholds. Methods: PubMed, Embase, the Cochrane Library, and China National Knowledge Infrastructure were searched from inception to 15 February 2026. Risk of bias was assessed using QUADAS-3. Sensitivity and specificity were pooled with a bivariate random-effects model, and heterogeneity was explored through subgroup analyses and metaregression. Thresholds were derived using likelihood ratio (LR)-based and diagmeta cutoff modeling. Results: Twelve studies (n = 1761) were included. Pooled sensitivity was 0.861 (95% confidence interval [CI]: 0.777–0.917) and specificity was 0.848 (95% CI: 0.781–0.897), with a positive LR (LR+) of 5.65 and a negative LR (LR−) of 0.164. At a 50% pretest probability, post-test probability was increased to 85% by a positive result and reduced to 14% by a negative result. Intracerebral hemorrhage cohorts showed lower accuracy (sensitivity: 0.675, specificity: 0.755), whereas brain tumor-predominant cohorts demonstrated the highest performance (sensitivity: 0.935, specificity: 0.922; p = 0.017). Thresholds of ≥41.3 (rule-in; LR+ ≥10) and ≤30.1 ng/mL (rule-out; LR− ≤0.1) defined clinically actionable decision zones. Conclusions: CSF HBP provides quantitatively defined rule-in and rule-out thresholds that meaningfully shift the post-test probability and may support antimicrobial decision-making in suspected HAVM. Prospective multicenter validation is warranted. Full article

The Citrobacter freundii (C. freundii) complex represents an increasingly significant group of opportunistic pathogens within healthcare settings. This bacterial complex demonstrates remarkable genomic plasticity, characterized by extensive horizontal gene transfer capabilities that facilitate rapid acquisition of resistance determinants and virulence factors. Although originally considered environmental organisms with limited pathogenic potential, members of the C. freundii complex have emerged as important nosocomial pathogens responsible for urinary tract infections, bacteremia, wound infections, and neonatal meningitis. Importantly, their clinical significance lies less in unique disease manifestations and more in the moderate risk of resistance emergence during therapy with third-generation cephalosporins, driven by inducible chromosomal AmpC β-lactamase production. Beyond this intrinsic mechanism, the genomic adaptability of the C. freundii complex also enables acquisition of additional resistance determinants, including extended-spectrum β-lactamases (ESBLs) and carbapenemases, further limiting therapeutic options and complicating clinical management. Understanding the molecular mechanisms underlying genomic plasticity, virulence expression, and resistance development in the C. freundii complex is crucial for developing effective diagnostic strategies, infection control measures, and novel therapeutic approaches. This pathogen exemplifies the challenge of emerging multidrug-resistant bacteria in contemporary healthcare and underscores the need for continued surveillance and research. This narrative review provides current insights into the taxonomy, genomic plasticity, virulence, and mechanisms of antibiotic resistance. Full article

Background/Objectives: Bacterial meningitis is a severe disease with a fatality rate of 5–50%. It is mainly caused by Streptococcus pneumoniae or Neisseria meningitidis, which can also cause simultaneous infections outside the central nervous system. Toll-like receptors (TLRs) have an important role in the innate immune system. The TLR2 subfamily comprises the four highly homologous members TLR1, TLR2, TLR6, and TLR10, which also have an important immunomodulatory role in infectious diseases. Methods: The study cohort consists of 190 bacterial meningitis patients aged 1 to 147 months from randomized clinical trials and 268 controls from Luanda, Angola. Polymorphisms of TLR2 (rs111200466) and TLR10 (rs10856837 and rs11096956) were determined using PCR-based methods and Sanger sequencing. The genotyping results were analyzed together with clinical data to determine whether gene polymorphisms of TLR2 and TLR10 are associated with susceptibility and outcome of bacterial meningitis in Angolan children. Results: At admission and during hospitalization, patients with pneumococcal meningitis carrying a variant (ins/del or del/del) of TLR2 rs111200466 had a significantly lower risk of coexisting infections (OR 0.27; 95% CI 0.11–0.65; p = 0.004), particularly pneumonia (OR 0.18; 95% CI 0.06–0.49; p = 0.001). In addition, haplotype analysis demonstrated that a variant genotype of TLR2 rs111200466 together with a wildtype of TLR10 SNPs (rs10856837 and rs11096956) may protect against coexisting pneumonia (OR 0.2; 95% CI 0.06–0.6; p = 0.007). Conclusions: This study suggests an association between coexisting infection and genetic variation in TLR2 and TLR10 of bacterial meningitis in Angolan children. Full article

Background and Objectives: Viral meningitis presents significant diagnostic challenges. The aim of this study was to identify predictive factors for meningitis etiology and clinical outcomes. Methods: This prospective, single center, comparative study enrolled patients meeting clinical, biological, and microbiological criteria for bacterial (BM) or viral (VM) meningitis. Serum inflammatory markers, namely the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII), were quantified. In addition, the concentrations of oxidative stress biomarkers, glutathione peroxidase 3 (GPx3) and copper/zinc superoxide dismutase (Cu/Zn SOD), were also determined. Spearman correlation and logistic regression were used to evaluate associations between biomarkers and etiology, while receiver operating characteristic (ROC) curves assessed outcome correlations. Results: VM patients showed a significantly lower NLR (p = 0.007), PLR (p = 0.010), and SII (p = 0.016), with higher GPx3 (p < 0.0001) levels compared with BM patients. Cu/Zn SOD showed no significant difference (p = 0.442) between groups. Multivariate logistic regression identified the SII (OR = 1.015; 95% CI = 1.004–1.026) and GPx3 (OR = 0.847; 95% CI = 0.740–0.970) as etiology predictors. The SII was the strongest predictor of mortality in VM (AUC = 0.833). Conclusions: Serum markers of inflammation, including the systemic immune–inflammation index, along with antioxidant indicators such as GPx3, may serve as valuable additional tools for predicting meningitis etiology and forecasting patient outcomes. Full article

Background: Meningoencephalitis is a complex inflammatory condition of the CNS that can result in significant morbidity and mortality in critically ill adults. Accurate and timely neuromonitoring is essential for guiding management and improving outcomes. This study aimed to descriptively evaluate the prognostic value of early TCCD monitoring, particularly the pulsatility index, and its integration with conventional and perfusion MRI in patients with meningoencephalitis. Methods: We present an observational, retrospective, cohort study involving ten adult patients (median age 56 years, IQR 45.5–68.5; mean 55.9, range 35–76) with neurological syndromes caused by suspected or confirmed infectious meningoencephalitis. Etiologies included bacterial meningitis/meningoencephalitis (50%), viral meningoencephalitis (10%), neurotoxoplasmosis (10%), progressive multifocal leukoencephalopathy (10%), and undetermined origin (20%). Patients underwent TCCD and MRI within 24 h. In five cases, standard MRI sequences were acquired, while in the remaining five, perfusion imaging was performed using Arterial Spin Labelling (ASL). A favorable outcome was defined as survival with neurological recovery (Glasgow Outcome Scale > 5) at ICU discharge. Results: TCCD-derived PI provided valuable information on cerebral hemodynamics. PI values ≤ 1.25 were associated with favorable clinical outcomes and symmetrical MRI findings. Conversely, PI > 1.25 correlated with poor prognosis and often preceded MRI-detectable structural damage. When combined with ASL, PI mirrored the detected perfusion asymmetries and was associated with poor prognosis in fatal cases. Conclusions: Bedside TCCD can offer real-time assessment of cerebrovascular dynamics and, when integrated with conventional and ASL MRI, could enhance the understanding of pathophysiological processes in meningoencephalitis, supporting timely and informed decisions in neurocritical care. Full article

Background/Objectives: Rapid pathogen identification is essential to optimize antimicrobial therapy and improve patient outcomes, particularly in severe infections. Syndromic molecular diagnostics have been introduced to overcome the limitations of conventional culture-based methods. This study evaluated the diagnostic performance and real-life implementation of BioFire^® FilmArray^® syndromic panels compared with routine microbiological diagnostics. Methods: A total of 955 clinical specimens collected between 2022 and June 2025 were retrospectively analyzed, including positive blood cultures (n = 400), lower respiratory tract samples (n = 309), cerebrospinal fluid (n = 158) and stool specimens (n = 88). FilmArray^® BCID2, Pneumonia Plus, Meningitis/Encephalitis and Gastrointestinal panels were performed on the Biofire Fimarray^® instrument according to clinical indication and compared with conventional culture-based identification and phenotypic antimicrobial susceptibility testing. Results: Overall diagnostic concordance between BioFire^® FilmArray^® syndromic panels and conventional methods was high across all specimen types, with the highest positive percent agreement (PPA) observed for bloodstream infections (97.7%) and gastrointestinal pathogens (100%). In respiratory samples, the Pneumonia Plus panel detected a considerable number of microorganisms that could not be identified by culture, including viral pathogens and fastidious bacteria. Molecular detection of antimicrobial resistance markers showed excellent concordance with phenotypic profiles, with 100% agreement for CTX-M, carbapenemases (KPC, NDM, OXA-48-like, IMP), and vanA/B, while lower concordance was observed for mecA/C in staphylococci. In parallel, semi-quantitative bacterial loads provided by the Pneumonia Plus panel showed a strong essential agreement with culture-based quantification (97.4%, ±1 log₁₀). Across all panels, syndromic testing significantly reduced diagnostic turnaround time. Conclusions: Syndromic molecular panels provide rapid and reliable simultaneous detection of pathogens, as well as early resistance marker detection, thereby supporting timely antimicrobial optimization and stewardship when integrated with conventional microbiological diagnostics. Full article

Background/Objective: To identify the risks and outcomes of extensively drug-resistant Gram-negative bacilli (XDR-GNB) in neonates. Methods: This retrospective case–control study (1995–2024) included neonates with late-onset sepsis (n = 132) and XDR-GNB bacteremia (n = 26) compared with those without XDR-GNB (n = 106). Results: Median gestational age was 31 weeks and birth weight 1540 g. The prevalence of XDR-GNB was 19.7%. The most common XDR-GNB and non-XDR-GNB pathogens were Acinetobacter baumannii and Klebsiella pneumoniae. Sepsis onset occurred earlier in the XDR-GNB group than in the non-XDR-GNB group (7.0 vs. 12.5 days, p = 0.005). In multivariable analysis using Firth’s penalized likelihood method, the XDR-GNB group was more likely to have gastrointestinal anomalies (adjusted odds ratio 3.81, 95% confidence interval 1.24–12.01, p = 0.02) and history of umbilical arterial catheterization (adjusted odds ratio 3.04, 95% confidence interval 1.21–7.95, p = 0.02) compared to the non-XDR-GNB group. The XDR-GNB group had higher rates of septic shock (50.0% vs. 18.9%, p = 0.002) and inadequate empiric antimicrobial therapy (34.6% vs. 13.2%, p = 0.02). The non-susceptibility rates to third-generation cephalosporins, gentamicin, carbapenems, amikacin, and colistin were 83.3%, 58.3%, 48.1%, 30.4%, and 4.4%, respectively. Conclusions: Empirical colistin treatment is warranted for neonates in high-XDR environments who exhibit septic shock and have specific risk factors, such as gastrointestinal anomalies or the presence of an umbilical arterial catheter. Multimodal interventions, including antimicrobial stewardship programs, have been used to prevent or reduce the incidence of neonatal XDR-GNB sepsis. Full article

Background: Streptococcus pneumoniae is currently the leading cause of acute bacterial meningitis. This study assessed the impact of pneumococcal conjugate vaccines (PCVs) on pneumococcal meningitis in Gipuzkoa, north of Spain, between 1993 and 2023. Methods: All cases were serotyped and tested for antimicrobial susceptibility, with medical records reviewed since 2013. Overall, 193 patients were diagnosed (178 patients), averaging 6.2 cases annually. Results: Pneumococcal meningitis annual incidence decreased significantly after PCVs introduction, from 1.99 cases per 100,000 inhabitants in 1993–2001 (before PCV7) to 1.64 in 2002–2010 (PCV7 period) and further to 1.13 in 2011–2023 (PCV13 period). This decline was observed in all age groups except for adults aged ≥65 years, in whom the reduction was observed only after PCV13 introduction. The greatest reduction was observed in children under five. The incidence of meningitis caused by vaccine serotypes decreased following the progressive introduction of PCVs, but non-PCV serotypes increased from 0.70 to 0.95 cases per 100,000 between 1993–2001 and 2011–2023. Otitis media was the most common source of infection, followed by CSF fistula. Most cases (85%) required ICU admission; 67.5% showed sequels at discharge, mainly sensorineural hearing loss, and the 30-day mortality rate was 11.1%. Recurrent pneumococcal meningitis represented 7.8% of cases, associated with head trauma, with favorable outcomes and no mortality. Between 1993–2001 and 2002–2010, penicillin and cefotaxime resistance decreased from 25.4% to 13.3% (47.6% reduction) and from 19.7% to 5% (74.6% reduction), respectively. In 2011–2023, cefotaxime resistance stabilized, but penicillin resistance rose to 32.3%, mainly due to non-PCV13 serotypes. Conclusions: The use of PCV reduced the incidence of pneumococcal meningitis in the region, but penicillin resistance has increased in recent years, due to the rise in non-PCV13 serotypes. Full article

Background: Streptococcus pneumoniae (Spn) is a leading bacterial pathogen responsible for severe invasive diseases, including meningitis, sepsis, and pneumonia. Current pneumococcal vaccines, which are all based on capsular polysaccharide antigens, provide limited protection and are further compromised by post-vaccination serotype replacement. Pneumococcal surface protein A (PspA), a highly conserved virulence factor expressed across diverse serotypes, has emerged as a promising candidate antigen for novel protein-based vaccines. However, progress in this field has been hindered by the absence of standardized in vitro functional antibody assays. Methods: This study established a robust functional antibody detection method for PspA-based protein vaccines by modifying the conventional multiplex opsonophagocytic killing assay (MOPA), originally designed for polysaccharide-based vaccines. Using polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) typing, a target strain panel was selected and developed to include representative strains from PspA Family 1-Clade 2 and Family 2-Clades 3 and 4. The MOPA protocol was optimized by extending the phagocytic reaction time to enhance sensitivity. Specificity was confirmed through recombinant PspA competitive inhibition assays. Results: The assay demonstrated high linearity (R² ≥ 0.98) between opsonophagocytic index (OI) and serum dilution, along with acceptable repeatability (CV ≤ 30%) and intermediate precision (CV ≤ 50%). Both preclinical and clinical serum samples exhibited potent bactericidal activity against diverse PspA families, independent of capsule type. Conclusions: This study provided a standardized framework to support the development and regulatory assessment of protein-based pneumococcal vaccines. Full article

Among many metal ions in biological systems, iron plays a fundamental role. Transferrins are iron-binding glycoproteins responsible for transporting Fe³⁺ in vertebrate blood. Neisseria meningitidis, a Gram-negative pathogen causing meningitis, relies on iron for survival and acquires it from human transferrin (hTf) using two surface proteins, TbpA and TbpB. These proteins interact with hTf to form a ternary TbpA–TbpB–hTf complex, enabling iron capture from the host. The absence of an experimental crystal structure for this complex has hindered computational studies, a detailed understanding of Fe³⁺ dissociation, and designing efficient therapeutics. This study presents the first computational model of the ternary complex, its validation, and molecular dynamics simulations. Structural analyses revealed key electrostatic interactions regulating Fe³⁺ coordination and essential contact regions between proteins. The role of Lys359 from TbpA was investigated via QM/MM calculations by evaluating Fe³⁺ binding energies of isolated hTf, the ternary complex, and Lys359Ala, Lys359Arg, Lys359Asp mutant models. Results revealed that the proton transfer from Lys359 leads to disruption of Tyr517–Fe³⁺ coordination, facilitating iron transfer to the bacterial system. Natural bond orbital analysis confirmed this mechanism. The findings provide new molecular insight into N. meningitidis iron acquisition and identify Lys359 as a potential target for covalent inhibitor design, guiding the development of novel therapeutics against meningococcal infection. Full article