Vibrio vulnificus meningoencephalitis in a patient with thalassemia and a splenectomy

Vibrio vulnificus-A Review with a Special Focus on Sepsis

Vibrio vulnificus (V. vulnificus) is a Gram-negative, halophilic bacillus known for causing severe infections such as gastroenteritis, necrotizing fasciitis, and septic shock, with mortality rates exceeding 50% in high-risk individuals. Transmission occurs primarily through the consumption of contaminated seafood, exposure of open wounds to infected water, or, in rare cases, insect bites. The bacterium thrives in warm, brackish waters with high salinity levels, and its prevalence is rising due to the effects of climate change, including warming ocean temperatures and expanding coastal habitats. High-risk populations include individuals with underlying conditions such as chronic liver disease, diabetes, or immunosuppression, which heighten susceptibility to severe outcomes. The pathogenicity of V. vulnificus is mediated by an array of virulence factors, including hemolysins, proteases, and capsular polysaccharides, as well as mechanisms facilitating iron acquisition and immune system evasion. Clinical manifestations range from localized gastrointestinal symptoms to life-threatening systemic infections such as septicemia. Rare but severe complications, including pneumonia and meningitis, have also been reported. Treatment typically involves the use of doxycycline in combination with third-generation cephalosporins, although the emergence of multidrug-resistant strains is an escalating concern. Alternative therapeutic approaches under investigation include natural compounds such as resveratrol and the application of antimicrobial blue light. For necrotizing infections, prompt and aggressive surgical intervention remains essential to improving patient outcomes. As global temperatures continue to rise, understanding the epidemiology of V. vulnificus and developing innovative therapeutic strategies are critical to mitigating its growing public health impact.

Application of metagenomic next-generation sequencing in the diagnosis of infectious diseases

Metagenomic next-generation sequencing (mNGS) is a transformative approach in the diagnosis of infectious diseases, utilizing unbiased high-throughput sequencing to directly detect and characterize microbial genomes from clinical samples. This review comprehensively outlines the fundamental principles, sequencing workflow, and platforms utilized in mNGS technology. The methodological backbone involves shotgun sequencing of total nucleic acids extracted from diverse sample types, enabling simultaneous detection of bacteria, viruses, fungi, and parasites without prior knowledge of the infectious agent. Key advantages of mNGS include its capability to identify rare, novel, or unculturable pathogens, providing a more comprehensive view of microbial communities compared to traditional culture-based methods. Despite these strengths, challenges such as data analysis complexity, high cost, and the need for optimized sample preparation protocols remain significant hurdles. The application of mNGS across various systemic infections highlights its clinical utility. Case studies discussed in this review illustrate its efficacy in diagnosing respiratory tract infections, bloodstream infections, central nervous system infections, gastrointestinal infections, and others. By rapidly identifying pathogens and their genomic characteristics, mNGS facilitates timely and targeted therapeutic interventions, thereby improving patient outcomes and infection control measures. Looking ahead, the future of mNGS in infectious disease diagnostics appears promising. Advances in bioinformatics tools and sequencing technologies are anticipated to streamline data analysis, enhance sensitivity and specificity, and reduce turnaround times. Integration with clinical decision support systems promises to further optimize mNGS utilization in routine clinical practice. In conclusion, mNGS represents a paradigm shift in the field of infectious disease diagnostics, offering unparalleled insights into microbial diversity and pathogenesis. While challenges persist, ongoing technological advancements hold immense potential to consolidate mNGS as a pivotal tool in the armamentarium of modern medicine, empowering clinicians with precise, rapid, and comprehensive pathogen detection capabilities.

Healthy adults with Streptococcus pneumoniae meningitis and Streptococcus pneumoniae subdural abscess: two case reports and a literature review

We present the cases of two otherwise healthy adults, one with meningitis and another with a subdural abscess, with both conditions attributable to Streptococcus pneumoniae. A 31-year-old man was admitted with a 3-day history of fever, headache, and vomiting. Physical examination revealed intermittent confusion, irritability, and neck stiffness. Cerebrospinal fluid (CSF) culture was positive for S. pneumoniae. Contrast-enhanced magnetic resonance imaging (C-MRI) revealed multiple small lesions on the bilateral frontal lobes. Intravenous ceftriaxone and vancomycin were administered, followed by intravenous moxifloxacin. His symptoms resolved within 3 months. Additionally, a 66-year-old man was admitted for acute fever with confusion, abnormal behavior, and a recent history of acute respiratory infection. Physical examination revealed confusion, neck stiffness, and a positive right Babinski sign. CSF metagenomic analysis detected S. pneumoniae. C-MRI disclosed left occipitotemporal meningoencephalitis with subdural abscesses. Intravenous ceftriaxone was administered for 3 weeks. His condition gradually improved, with resorbed lesions detected on repeat MRI. This study expanded the clinical and imaging spectra of S. pneumoniae meningitis. In healthy adults, S. pneumoniae can invade the brain, but subdural abscess is a rare neuroimaging manifestation. Early diagnosis of S. pneumoniae meningitis by high-throughput sequencing and flexible treatment strategies are necessary for satisfactory outcomes.

An Assay Combining Droplet Digital PCR With Propidium Monoazide Treatment for the Accurate Detection of Live Cells of Vibrio vulnificus in Plasma Samples

Vibrio vulnificus (V. vulnificus) is one of the most common pathogenic Vibrio species to humans; therefore, the establishment of timely and credible detection methods has become an urgent requirement for V. vulnificus illness surveillance. In this study, an assay combining droplet digital PCR (ddPCR) with propidium monoazide (PMA) treatment was developed for detecting V. vulnificus. The primers/probes targeting the V. vulnificus hemolysin A (vvhA) gene, amplification procedures, and PMA processing conditions involved in the assay were optimized. Then, we analyzed the specificity, sensitivity, and ability to detect live cell DNA while testing the performance of PMA-ddPCR in clinical samples. The optimal concentrations of primers and probes were 1.0 and 0.3 μM, respectively. The annealing temperature achieving the highest accuracy in ddPCR assay was 60°C. With an initial V. vulnificus cell concentration of 10⁸ CFU/mL (colony-forming units per milliliter), the optimal strategy to distinguish live cells from dead cells was to treat samples with 100 μM PMA for 15 min in the dark and expose them to LED light with an output wavelength of 465 nm for 10 min. The specificity of the PMA-ddPCR assay was tested on 27 strains, including seven V. vulnificus strains and 20 other bacterial strains. Only the seven V. vulnificus strains were observed with positive signals in specificity analysis. Comparative experiments on the detection ability of PMA-ddPCR and PMA-qPCR in pure cultures and plasma samples were performed. The limit of detection (LOD) and the limit of quantitation (LOQ) in pure culture solutions of V. vulnificus were 29.33 and 53.64 CFU/mL in PMA-ddPCR, respectively. For artificially clinical sample tests in PMA-ddPCR, V. vulnificus could be detected at concentrations as low as 65.20 CFU/mL. The sensitivity of the PMA-ddPCR assay was 15- to 40-fold more sensitive than the PMA-qPCR in this study. The PMA-ddPCR assay we developed provides a new insight to accurately detect live cells of V. vulnificus in clinical samples, which is of great significance to enhance public health safety and security capability and improve the emergency response level for V. vulnificus infection.

High-Throughput Metagenomics for Identification of Pathogens in the Clinical Settings

The application of sequencing technology is shifting from research to clinical laboratories owing to rapid technological developments and substantially reduced costs. However, although thousands of microorganisms are known to infect humans, identification of the etiological agents for many diseases remains challenging as only a small proportion of pathogens are identifiable by the current diagnostic methods. These challenges are compounded by the emergence of new pathogens. Hence, metagenomic next-generation sequencing (mNGS), an agnostic, unbiased, and comprehensive method for detection, and taxonomic characterization of microorganisms, has become an attractive strategy. Although many studies, and cases reports, have confirmed the success of mNGS in improving the diagnosis, treatment, and tracking of infectious diseases, several hurdles must still be overcome. It is, therefore, imperative that practitioners and clinicians understand both the benefits and limitations of mNGS when applying it to clinical practice. Interestingly, the emerging third-generation sequencing technologies may partially offset the disadvantages of mNGS. In this review, mainly: a) the history of sequencing technology; b) various NGS technologies, common platforms, and workflows for clinical applications; c) the application of NGS in pathogen identification; d) the global expert consensus on NGS-related methods in clinical applications; and e) challenges associated with diagnostic metagenomics are described.

In hot water: effects of climate change on Vibrio-human interactions

Sea level rise and the anthropogenic warming of the world's oceans is not only an environmental tragedy, but these changes also result in a significant threat to public health. Along with coastal flooding and the encroachment of saltwater farther inland comes an increased risk of human interaction with pathogenic Vibrio species, such as Vibrio cholerae, V. vulnificus and V. parahaemolyticus. This minireview examines the current literature for updates on the climatic changes and practices that impact the location and duration of the presence of Vibrio spp., as well as the infection routes, trends and virulence factors of these highly successful pathogens. Finally, an overview of current treatments and methods for the mitigation of both oral and cutaneous exposures are presented.

The Feasibility of Metagenomic Next-Generation Sequencing to Identify Pathogens Causing Tuberculous Meningitis in Cerebrospinal Fluid

Purpose

The application of metagenomic next-generation sequencing (mNGS) in the diagnosis of tuberculous meningitis (TBM) remains poorly characterized. Here, we retrospectively analyzed data from patients with TBM who had taken both mNGS and conventional tests including culture of Mycobacterium tuberculosis (MTB), polymerase chain reaction (PCR) and acid-fast bacillus (AFB) stain, and the sensitivity and specificity of these methods were compared.

Methods

We retrospectively recruited TBM patients admitted to the hospital between December 2015 and October 2018. The first collection of cerebrospinal fluid (CSF) samples underwent both mNGS and conventional tests. In addition, patients with bacterial/cryptococcal meningitis or viral meningoencephalitis were mNGS positive controls, and a patient with auto-immune encephalitis was an mNGS negative control.

Results

Twenty three TBM patients were classified as 12 definite and 11 clinical diagnoses, which were based on clinical manifestations, pathogen evidence, CSF parameters, brain imaging, and treatment response. The mNGS method identified sequences of Mycobacterium tuberculosis complex (MBTC) from 18 samples (18/23, 78.26%). In patients with definite TBM, the sensitivity of mNGS, AFB, PCR, and culture to detect MTB in the first CSF samples were 66.67, 33.33, 25, and 8.33%, respectively. The specificity of each method was 100%. Among the four negative mNGS cases (4/23, 17.39%), three turned out positive by repeated AFB stain. The agreement of mNGS with the total of conventional methods was 44.44% (8/18). Combination of mNGS and conventional methods increased the detection rate to 95.65%. One patient was diagnosed as complex of TBM and cryptococcal meningitis, in which AFB stain and cryptococcal antigen enzyme immunoassay were positive and the DNA of Cryptococcus neoformans was detected by mNGS.

Conclusion

Our study indicates that mNGS is an alternative method to detect the presence of mycobacterial DNA in CSF samples from patients with TBM and deserves to be applied as a front-line CSF test.