Real-Time Mass Spectrometry Breath Analysis for the Investigation of Respiratory Tract Infections

Lower respiratory tract infections (LRTIs) remain a major global health burden, with diagnosis often challenged by clinical heterogeneity, overlapping symptoms, difficulty in obtaining quality biological specimens and limitations of conventional microbiological testing. Exhaled breath contains thousands of volatile organic compounds (VOCs), arising from both host metabolism and microbial activity, and provides a non-invasive window into the metabolic landscape of infection. Emerging evidence from in vitro studies, animal models, and clinical investigations supports the existence of pathogen-specific VOC signatures. However, most published studies have relied on offline methods, such as gas chromatography-mass spectrometry (GC-MS), and robust proof-of-concept for real-time, bedside analysis in diverse, real-world populations is lacking. Proton transfer reaction-mass spectrometry (PTR-MS) offers rapid, quantitative, and non-invasive assessment of breath VOCs in both spontaneously breathing and mechanically ventilated patients.