Clinical value of metagenomic next-generation sequencing in complicated infectious diseases

Metagenomic next-generation sequencing assistance in identifying non-tuberculous mycobacterial infections

Introduction

The advent of metagenomics next-generation sequencing (mNGS) has garnered attention as a novel method for detecting pathogenic infections, including Non-Tuberculous Mycobacterial (NTM) and tuberculosis (TB).However, the robustness and specificity of mNGS in NTM diagnostics have not been fully explored.

Methods

In this retrospective study, we enrolled 27 patients with NTM genomic sequences via mNGS and conducted a comprehensive clinical evaluation.

Results

Pulmonary NTM disease was the most commonly observed presentation, with a subset of patients also presenting with extrapulmonary NTM infections.mNGS analysis identified six distinct NTM species, primarily Mycobacteriumavium complex (MAC), followed by Mycobacterium intracellulare andMycobacterium abscessus. Conventional routine culture methods encountered challenges, resulting in negative results for all available 22 samples. Among the 10 patients who underwent quantitative polymerase chain reaction (qPCR) testing, five tested positive for NTM.

Discussion

It is important to note that further species typing is necessary to determine the specific NTM type, as traditional pathogen detection methods serve as an initial step. In contrast, when supplemented with pathogen data, enables the identification of specific species, facilitating precise treatment decisions. In conclusion, mNGS demonstrates significant potential in aidingthe diagnosis of NTMdisease by rapidly detecting NTM pathogens and guiding treatment strategies. Its enhanced performance, faster turnaround time (TAT), and species identification capabilities make mNGS a promising tool for managing NTM infections.

Case report: A rare case of pulmonary mucormycosis caused by Lichtheimia ramosa in pediatric acute lymphoblastic leukemia and review of Lichtheimia infections in leukemia

Mucormycosis caused by Lichtheimia ramosa is an emerging and uncommon opportunistic infection in patients with hematological malignancies, with high mortality rates. Herein, we first report a case of pulmonary mucormycosis with Lichtheimia ramosa in a 3-year-old girl recently diagnosed with B-cell acute lymphoblastic leukemia. The diagnosis was made using computerized tomography of the lung, metagenomic next-generation sequencing (mNGS) of blood and sputum specimens, and microscopic examination to detect the development of Lichtheimia ramosa on the surgical specimen. She was effectively treated after receiving prompt treatment with amphotericin B and posaconazole, followed by aggressive surgical debridement. In our case, the fungal isolates were identified as Lichtheimia ramosa using mNGS, which assisted clinicians in quickly and accurately diagnosing and initiating early intensive treatment. This case also indicated the importance of strong clinical suspicion, as well as aggressive antifungal therapy combined with surgical debridement of affected tissues.

[Application value of metagenomic next-generation sequencing for pathogen detection in childhood agranulocytosis with fever]

OBJECTIVES

To study the application value of metagenomic next-generation sequencing (mNGS) for pathogen detection in childhood agranulocytosis with fever.

METHODS

A retrospective analysis was performed on the mNGS results of pathogen detection of 116 children with agranulocytosis with fever who were treated from January 2020 to December 2021. Among these children, 38 children with negative mNGS results were enrolled as the negative group, and 78 children with positive results were divided into a bacteria group (n=22), a fungal group (n=23), and a viral group (n=31). Clinical data were compared between groups.

RESULTS

For the 116 children with agranulocytosis and fever, the median age was 8 years at diagnosis, the median turnaround time of mNGS results was 2 days, and the positive rate of mNGS testing was 67.2% (78/116). Compared with the negative group, the bacterial group had a higher procalcitonin level (P<0.05), the fungal group had higher level of C-reactive protein and positive rate of (1,3)-β-D glucan test/galactomannan test (P<0.05), and the fungal group had a longer duration of fever (P<0.05). Among the 22 positive microbial culture specimens, 9 (41%) were consistent with the mNGS results. Among the 17 positive blood culture specimens, 8 (47%) were consistent with the mNGS results. Treatment was adjusted for 28 children (36%) with the mNGS results, among whom 26 were cured and discharged.

CONCLUSIONS

The mNGS technique has a shorter turnaround time and a higher sensitivity for pathogen detection and can provide evidence for the pathogenic diagnosis of children with agranulocytosis and fever.

Clinical Application and Influencing Factor Analysis of Metagenomic Next-Generation Sequencing (mNGS) in ICU Patients With Sepsis

Objective

To analyze the clinical application and related influencing factors of metagenomic next-generation sequencing (mNGS) in patients with sepsis in intensive care unit (ICU).

Methods

The study included 124 patients with severe sepsis admitted to the ICU in the First Affiliated Hospital of Zhengzhou University from June 2020 to September 2021. Two experienced clinicians took blood mNGS and routine blood cultures of patients meeting the sepsis diagnostic criteria within 24 hours after sepsis was considered, and collection the general clinical data.

Results

mNGS positive rate was higher than traditional blood culture (67.74% vs. 19.35%). APACHE II score [odds ratio (OR)=1.096], immune-related diseases (OR=6.544), and hypertension (OR=2.819) were considered as positive independent factors for mNGS or culture-positive. The sequence number of microorganisms and pathogen detection (mNGS) type had no effect on prognosis. Age (OR=1.016), female (OR=5.963), myoglobin (OR=1.005), and positive virus result (OR=8.531) were independent risk factors of sepsis mortality. Adjusting antibiotics according to mNGS results, there was no statistical difference in the prognosis of patients with sepsis.

Conclusion

mNGS has the advantages of rapid and high positive rate in the detection of pathogens in patients with severe sepsis. Patients with high APACHE II score, immune-related diseases, and hypertension are more likely to obtain positive mNGS results. The effect of adjusting antibiotics according to mNGS results on the prognosis of sepsis needs to be further evaluated.