Small molecule biomarkers in infectious disease

Infectious disease disrupts host metabolism in profound ways, producing distinct small molecule signatures that reflect the underlying biological responses to infection. These metabolite changes offer valuable opportunities for biomarker discovery that may lead to new methods of diagnosis, therapeutic response monitoring, and treatment outcome prediction. In this chapter, we explore the generation of small molecule biomarkers during infection, highlighting how host-pathogen interaction gives rise to metabolic signatures and address key considerations with sample choice and preparation. We examine common instrumental platforms and analytical strategies for small molecule detection and data processing, and present case studies of established and emerging biomarkers. Lastly, we discuss recent advances and future directions which position small molecule biomarkers as a rapidly evolving and promising area in infectious disease diagnosis. Unfortunately, the vast majority of candidate biomarkers have yet to be translated into routine clinical use. Key barriers include the expense and complexity of advanced analytical technologies, lack of reproducibility across studies, regulatory hurdles, and the need for extensive clinical validation in diverse patient populations. Bridging this gap between discovery and clinical implementation will require technologic innovation as well as coordinated regulatory approval, cost reduction, and improved laboratory infrastructure. Importantly, the field is moving toward overcoming these barriers, with interdisciplinary collaboration and technological progress paving the way for more accessible, robust, and clinically relevant small molecule biomarker applications.