Pathogenic Detection by Metagenomic Next-generation Sequencing in Skin and Soft Tissue Infection.

Background/aim: Skin and soft tissue infections (SSTIs) can be life-threatening, but the conventional bacterial cultures have low sensitivity and are time-consuming. Metagenomic next-generation sequencing (mNGS) is widely used as a diagnostic tool for detecting pathogens from infection sites. However, the use of mNGS for pathogen detection in SSTIs and related research is still relatively limited.

Patients and methods: From January 2020 to October 2021, 19 SSTI samples from 16 patients were collected in a single center (Taichung Veterans General Hospital, Taichung, Taiwan). The clinical samples were simultaneously subjected to mNGS and conventional bacterial culture methods to detect pathogens. Clinical characteristics were prospectively collected through electronic chart review. The microbiological findings from conventional bacterial culture and mNGS were analyzed and compared.

Results: The mNGS method detected a higher proportion of multiple pathogens in SSTIs compared to conventional bacterial culture methods. Pseudomonas spp. was among the most commonly identified Gram-negative bacilli using mNGS. Additionally, the mNGS method identified several rare pathogens in patients with SSTIs, including Granulicatella adiacens, Bacillus thuringiensis, and Bacteroides fragilis. Antimicrobial resistance genes were detected in 10 samples (52.6%) using the mNGS method, including genes for extended-spectrum beta-lactamase, Ambler class C β-lactamases, and carbapenemase.

Conclusion: mNGS not only plays an important role in the detection of pathogens in soft tissue infections, but also informs clinical professionals about the presence of additional microbes that may be important for treatment decisions. Further studies comparing conventional pathogen culture with the mNGS method in SSTIs are required.