L. pneumophila Infection Diagnosed by tNGS in a Lady with Lymphadenopathy

Pathogen distribution and infection patterns in pediatric severe pneumonia: A targeted next-generation sequencing study

OBJECTIVE

Severe pneumonia in children represents a significant clinical challenge due to its high incidence and associated mortality. This study aimed to assess the distribution of pathogens and patterns of infection in pediatric patients with severe pneumonia.

METHODS

This study included 110 pediatric patients diagnosed with severe pneumonia, who were admitted to Guangxi Maternal and Child Health Hospital between July 2021 and November 2023. Pathogen-targeted next-generation sequencing (tNGS) was employed to identify respiratory pathogens in these cases.

RESULTS

Pathogens were detected in 109 out of 110 cases, yielding a positive detection rate of 99.09%. Among these cases, 25 (22.72%) involved single-pathogen infections, while 84 (76.36%) were characterized by mixed infections. The infection pattern in children with severe pneumonia was relatively common with bacterial-viral coinfection (28.2%, 31/110). A total of 39 pathogens were identified from the 110 children with severe pneumonia, with the top three pathogens being Mycoplasma pneumoniae (30.91%, 34/110), Human Respiratory Syncytial Virus Type A (26.36%, 29/110), and Human Herpesvirus (18.18%, 20/110). Notably, 38.2% (13/34) of the cases were found to have macrolide-resistant Mycoplasma pneumoniae (MRMP). Additionally, 40% (44/110) of the children required admission to the intensive care unit (ICU).

CONCLUSION

The application of tNGS demonstrates significant utility in the detection of pathogens in pediatric patients with severe pneumonia. The predominant pathogens identified in this study are Mycoplasma pneumoniae, Human Respiratory Syncytial Virus, and Human Herpesvirus. Furthermore, mixed infections involving multiple pathogens were observed in 76.36% of the cases, and a substantial proportion (40%) of these patients necessitated intensive care.

Significance of Combining Bronchoalveolar Lavage Fluid With Targeted Next-Generation Sequencing in the Pathogen Detection-Based Diagnosis of Pulmonary Infections

OBJECTIVE

In this study, we investigated the application value of bronchoalveolar lavage fluid (BALF) combined with targeted next-generation sequencing (tNGS) in the pathogen detection-based diagnosis of patients with lung infections.

METHOD

A retrospective analysis was conducted on patients who underwent tracheoscopy and conventional microbiological tests (CMTs) on BALF, coupled with metagenomic next-generation sequencing (mNGS) or tNGS. This investigation encompassed individuals with suspected lung infections at Tianjin First Central Hospital from March 2023 to July 2023. Diagnostic rates based on pathogens detected via tNGS were compared with CMTs within the tNGS group. Additionally, diagnostic rates obtained through tNGS were compared with mNGS between the two groups.

RESULTS

The data of a total of 169 patients (78 in the tNGS group and 91 in the mNGS group) were collected, and 145 patients (67 in the tNGS group and 78 in the mNGS group) were finally diagnosed with lung infections. The comprehensive positive pathogen detection-based diagnosis rate for tNGS was 86.6%, with a single-pathogen lung infection diagnosis rate of 85.7% and a mixed-pathogen pulmonary infection diagnosis rate of 88.0%. In contrast, the overall positive pathogen detection-based diagnosis rate for CMTs was 38.8%, comprising a single-pathogen pulmonary infection diagnosis rate of 28.6% and a mixed-pathogen pulmonary infection diagnosis rate of 20.0%. The difference in positive diagnosis rate was deemed statistically significant (p < 0.05). In the mNGS group, the overall pathogen detection-based diagnosis rate was 89.7%, with a single-pathogen pulmonary infection diagnosis rate of 84.9%, and a 100% diagnosis rate for mixed-pathogen pulmonary infections. There was no statistically significant difference in the positive diagnosis rate when compared with the tNGS group (p > 0.05).

CONCLUSION

In patients with pulmonary infections, the diagnosis rate based on BALF pathogen detection using tNGS exceeded that of CMTs, showing no statistically significant difference compared to mNGS.

Early and rapid diagnosis of Chlamydia psittaci pneumonia by tNGS in six patients: a case series

Background

Psittacosis is a zoonotic infectious disease caused by Chlamydia psittaci (C. psittaci) infection, which can be transmitted by birds, poultry and wild animals. The symptoms and imaging findings of C. psittaci pneumonia are atypical and primarily rely on etiological diagnosis. The incidence of C. psittaci infection has been significantly underestimated because of the low sensitivity and poor timeliness of traditional diagnostic methods. Therefore, early and accurate diagnosis of psittacosis remains a challenge.

Case presentation

A case series with six pneumonia patients who were admitted to our hospital in the period from January 2023 to June 2023 is presented. These patients exhibited acute onset and symptoms, including fever, cough, poor appetite, dry mouth, dizziness, chills, and chest tightness. Despite comprehensive laboratory and radiological examinations, the cause of the pneumonia remained unidentified. Therefore, a sample of bronchoalveolar lavage fluid (BALF) was tested via target next-generation sequencing (tNGS), which revealed a positive result for C. psittaci. Prompt adjustment of the treatment regimens upon identification of the pathogen led to favorable outcomes in all patients.

Conclusion

tNGS is a novel diagnostic technology that enables rapid, accurate and cost-effective detection of C. psittaci pneumonia. Early detection of C. psittaci can improve patient outcomes through timely adjustment of therapies.

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.

Epidemiology of Human Parainfluenza Virus Infections among Pediatric Patients in Hainan Island, China, 2021-2023

Human parainfluenza viruses (HPIVs) are the leading causes of acute respiratory tract infections (ARTIs), particularly in children. During the COVID-19 pandemic, non-pharmaceutical interventions (NPIs) significantly influenced the epidemiology of respiratory viruses. This study analyzed 19,339 respiratory specimens from pediatric patients with ARTIs to detect HPIVs using PCR or tNGS, focusing on the period from 2021 to 2023. HPIVs were identified in 1395 patients (7.21%, 1395/19,339), with annual detection rates of 6.86% (303/4419) in 2021, 6.38% (331/5188) in 2022, and 7.82% (761/9732) in 2023. Notably, both the total number of tests and HPIV-positive cases increased in 2023 compared to 2021 and 2022. Seasonal analysis revealed a shift in HPIV prevalence from winter and spring in 2021-2022 to spring and summer in 2023. Most HPIV-positive cases were in children aged 0-7 years, with fewer infections among those aged 7-18 years. Since June 2022, HPIV-3 has been the most prevalent serotype (59.55%, 524/880), whereas HPIV-2 had the lowest proportion (0.80%, 7/880). The proportions of HPIV-1 (24.89%, 219/880) and HPIV-4 (15.45%, 136/880) were similar. Additionally, the incidence of co-infections with other common respiratory pathogens has increased since 2021. This study highlights rising HPIV detection rates post-COVID-19 and underscores the need for continuous surveillance of HPIVs to inform public health strategies for future epidemic seasons.

Comparative analysis of metagenomic and targeted next-generation sequencing for pathogens diagnosis in bronchoalveolar lavage fluid specimens

Background

Although the emerging NGS-based assays, metagenomic next-generation sequencing (mNGS) and targeted next-generation sequencing (tNGS), have been extensively utilized for the identification of pathogens in pulmonary infections, there have been limited studies systematically evaluating differences in the efficacy of mNGS and multiplex PCR-based tNGS in bronchoalveolar lavage fluid (BALF) specimens.

Methods

In this study, 85 suspected infectious BALF specimens were collected. Parallel mNGS and tNGS workflows to each sample were performed; then, we comparatively compared their consistency in detecting pathogens. The differential results for clinically key pathogens were confirmed using PCR.

Results

The microbial detection rates of BALF specimens by the mNGS and tNGS workflows were 95.18% (79/83) and 92.77% (77/83), respectively, with no significant difference. mNGS identified 55 different microorganisms, whereas tNGS detected 49 pathogens. The comparative analysis of mNGS and tNGS revealed that 86.75% (72/83) of the specimens were complete or partial concordance. Particularly, mNGS and tNGS differed significantly in detection rates for some of the human herpesviruses only, including Human gammaherpesvirus 4 (P<0.001), Human betaherpesvirus 7 (P<0.001), Human betaherpesvirus 5 (P<0.05) and Human betaherpesvirus 6 (P<0.01), in which tNGS always had higher detection rates. Orthogonal testing of clinically critical pathogens showed a total coincidence rate of 50% for mNGS and PCR, as well as for tNGS and PCR.

Conclusions

Overall, the performance of mNGS and multiplex PCR-based tNGS assays was similar for bacteria and fungi, and tNGS may be superior to mNGS for the detection of DNA viruses. No significant differences were seen between the two NGS assays compared to PCR.

Causal relationship between air pollution and infections: a two-sample Mendelian randomization study

Background

Traditional observational studies exploring the association between air pollution and infections have been limited by small sample sizes and potential confounding factors. To address these limitations, we applied Mendelian randomization (MR) to investigate the potential causal relationships between particulate matter (PM2.5, PM2.5-10, and PM10), nitrogen dioxide, and nitrogen oxide and the risks of infections.

Methods

Single nucleotide polymorphisms (SNPs) related to air pollution were selected from the genome-wide association study (GWAS) of the UK Biobank. Publicly available summary data for infections were obtained from the FinnGen Biobank and the COVID-19 Host Genetics Initiative. The inverse variance weighted (IVW) meta-analysis was used as the primary method for obtaining the Mendelian randomization (MR) estimates. Complementary analyses were performed using the weighted median method, MR-Egger method, and MR Pleiotropy Residual Sum and Outlier (MR-PRESSO) test.

Results

The fixed-effect IVW estimate showed that PM2.5, PM2.5-10 and Nitrogen oxides were suggestively associated with COVID-19 [for PM2.5: IVW (fe): OR 3.573(1.218,5.288), PIVW(fe) = 0.021; for PM2.5-10: IVW (fe): OR 2.940(1.385,6.239), PIVW(fe) = 0.005; for Nitrogen oxides, IVW (fe): OR 1.898(1.318,2.472), PIVW(fe) = 0.010]. PM2.5, PM2.5-10, PM10, and Nitrogen oxides were suggestively associated with bacterial pneumonia [for PM2.5: IVW(fe): OR 1.720 (1.007, 2.937), PIVW(fe) = 0.047; for PM2.5-10: IVW(fe): OR 1.752 (1.111, 2.767), P IVW(fe) = 0.016; for PM10: IVW(fe): OR 2.097 (1.045, 4.208), PIVW(fe) = 0.037; for Nitrogen oxides, IVW(fe): OR 3.907 (1.209, 5.987), PIVW(fe) = 0.023]. Furthermore, Nitrogen dioxide was suggestively associated with the risk of acute upper respiratory infections, while all air pollution were not associated with intestinal infections.

Conclusions

Our results support a role of related air pollution in the Corona Virus Disease 2019, bacterial pneumonia and acute upper respiratory infections. More work is need for policy formulation to reduce the air pollution and the emission of toxic and of harmful gas.

Circulation pattern and genetic variation of rhinovirus infection among hospitalized children on Hainan Island, before and after the dynamic zero-COVID policy, from 2021 to 2023

Throughout the COVID-19 pandemic, rhinovirus (RV) remained notable persistence, maintaining its presence while other seasonal respiratory viruses were largely suppressed by pandemic restrictions during national lockdowns. This research explores the epidemiological dynamics of RV infections among pediatric populations on Hainan Island, China, specifically focusing on the impact before and after the zero-COVID policy was lifted. From January 2021 to December 2023, 19 680 samples were collected from pediatric patients hospitalized with acute lower respiratory tract infections (ARTIs) at the Hainan Maternal and Child Health Hospital. The infection of RV was detected by tNGS. RV species and subtypes were identified in 32 RV-positive samples representing diverse time points by analyzing the VP4/VP2 partial regions. Among the 19 680 pediatric inpatients with ARTIs analyzed, 21.55% were found to be positive for RV infection, with notable peaks observed in April 2021 and November 2022. A gradual annual decline in RV infections was observed, alongside a seasonal pattern of higher prevalence during the colder months. The highest proportion of RV infections was observed in the 0-1-year age group. Phylogenetic analysis on 32 samples indicated a trend from RV-A to RV-C in 2022. This observation suggests potential evolving dynamics within the RV species although further studies are needed due to the limited sample size. The research emphasizes the necessity for ongoing surveillance and targeted management, particularly for populations highly susceptible to severe illnesses caused by RV infections.

Post-COVID-19 Pandemic Rebound of Macrolide-Resistant Mycoplasma pneumoniae Infection: A Descriptive Study

The rebound characteristics of respiratory infections after lifting pandemic control measures were uncertain. From January to November 2023, patients presenting at a teaching hospital were tested for common respiratory viruses and Mycoplasma pneumoniae using a combination of antigen, nucleic acid amplification, and targeted next-generation sequencing (tNGS) tests. The number and rate of positive tests per month, clinical and microbiological characteristics were analyzed. A rapid rebound of SARS-CoV-2 was followed by a slower rebound of M. pneumoniae, with an interval of 5 months between their peaks. The hospitalization rate was higher, with infections caused by respiratory viruses compared to M. pneumoniae. Though the pediatric hospitalization rate of respiratory viruses (66.1%) was higher than that of M. pneumoniae (34.0%), the 4094 cases of M. pneumoniae within 6 months posed a huge burden on healthcare services. Multivariate analysis revealed that M. pneumoniae-infected adults had more fatigue, comorbidities, and higher serum C-reactive protein, whereas children had a higher incidence of other respiratory pathogens detected by tNGS or pathogen-specific PCR, fever, and were more likely to be female. A total of 85% of M. pneumoniae-positive specimens had mutations detected at the 23rRNA gene, with 99.7% showing A2063G mutation. Days to defervescence were longer in those not treated by effective antibiotics and those requiring a change in antibiotic treatment. A delayed but significant rebound of M. pneumoniae was observed after the complete relaxation of pandemic control measures. No unusual, unexplained, or unresponsive cases of respiratory infections which warrant further investigation were identified.

Multiple pulmonary cavities in an immunocompetent patient: a case report and literature review

Legionella pneumonia (LP) is a relatively uncommon yet well-known type of atypical community-acquired pneumonia (CAP). It is characterized by a rapid progression to severe pneumonia and can be easily misdiagnosed. In most patients, chest computed tomography (CT) showed patchy infiltration, which may progress to lobar infiltration or even lobar consolidation. While pulmonary cavities are commonly observed in immunocompromised patients with LP, they are considered rare in immunocompetent individuals. Herein, we present a case of LP in an immunocompetent patient with multiple cavities in both lungs. Pathogen detection was performed using metagenomic next-generation sequencing (mNGS). This case highlights the unusual radiographic presentation of LP in an immunocompetent patient and emphasizes the importance of considering LP as a possible diagnosis in patients with pulmonary cavities, regardless of their immune status. Furthermore, the timely utilization of mNGS is crucial for early pathogen identification, as it provides multiple benefits in enhancing the diagnosis and prognosis of LP patients.