Unlocking the diagnostic and therapeutic potential of metagenomics

During the past decade, rapid advancements in sequencing technologies have enabled the study of human-associated microbiomes at an unprecedented scale. Metagenomics, specifically, is emerging as a clinical tool to identify the agents of infection, track the spread of diseases, and surveil potential pathogens. Yet, despite advances in high-throughput sequencing technologies and bioinformatics algorithms, metagenomics still has limitations barring mass clinical acceptance and broad implementation. Algorithms currently struggle to balance sensitivity and specificity of discovered biomarkers, genomic reference databases are incomplete, and studies are frequently not reproducible beyond the original environmental settings. Once these hurdles are overcome, clinical metagenomics will be able to inform doctors of the best, targeted treatment for their patients and provide early detection of disease. Here we present an overview of metagenomics methods with a discussion of computational challenges and limitations. Our review covers clinical applications and presents applications for strain identification of Mycobacterium tuberculosis (TB), identification of infectious agents in cases of encephalitis, biomarkers for Inflammatory Bowel Disease, and explores the challenges of sampling the microbiome in various tissues. Our review also summarizes 11 of the most recent clinical metagenomics studies and discusses their commonalities and unique features.