The Use of Microbial Metabolites for the Diagnosis of Infectious Diseases

Abstract

Volatile organic compounds (VOCs) produced by microbes through their primary and secondary metabolism can be used to identify infections caused by these organisms. The detection of microbial VOCs in human breath allows noninvasive, rapid, species-specific diagnosis of these infections. However, the detection and identification of these microbe-specific breath VOC signatures are still quite challenging due to the very low abundance of microbial VOCs in human breath. Pre-concentration of these VOCs, which are highly diluted in human breath, is important for the evaluation of these metabolites. In this chapter, we discuss methods for pre-concentration of VOCs using sorbent materials, solid-phase microextraction, and headspace sorptive extraction, and review common analytical techniques used to analyze breath VOCs, such as gas chromatography-mass spectrometry, soft ionization mass spectrometry techniques, ion mobility spectrometry, differential mobility spectrometry, and electronic nose sensors.