Exhaled human breath analysis in active pulmonary tuberculosis diagnostics by comprehensive gas chromatography-mass spectrometry and chemometric techniques

Abstract

Tuberculosis (TB) is the deadliest infectious disease, and yet accurate diagnostics for the disease are unavailable for many subpopulations. In this study, we investigate the possibility of using human breath for the diagnosis of active TB among TB suspect patients, considering also several risk factors for TB for smokers and those with human immunodeficiency virus (HIV). The analysis of exhaled breath, as an alternative to sputum-dependent tests, has the potential to provide a simple, fast, non-invasive, and readily available diagnostic service that could positively change TB detection. A total of 50 individuals from a clinic in South Africa were included in this pilot study. Human breath has been investigated in the setting of active TB using the thermal desorption-comprehensive two-dimensional gas chromatography-time of flight mass spectrometry methodology and chemometric techniques. From the entire spectrum of volatile metabolites in breath, three machine learning algorithms (support vector machines, partial least squares discriminant analysis, and random forest) to select discriminatory volatile molecules that could potentially be useful for active TB diagnosis were employed. Random forest showed the best overall performance, with sensitivities of 0.82 and 1.00 and specificities of 0.92 and 0.60 in the training and test data respectively. Unsupervised analysis of the compounds implicated by these algorithms suggests that they provide important information to cluster active TB from other patients. These results suggest that developing a non-invasive diagnostic for active TB using patient breath is a potentially rich avenue of research, including among patients with HIV comorbidities.

Rapid breath analysis for acute respiratory distress syndrome diagnostics using a portable 2-dimensional gas chromatography device

“…The 2 nd -dimensional module consisted of two identical channels, each of which had a 3 m long polar SUPELCOWAX ® 10 column (250 µm x 0.25 µm, Sigma Aldrich). Note that while polar columns have been used in the 2 nd -dimensional column in 2D GC analysis of breath 28,29 , mid-polar columns can also be used 30 .…”

“…A 2D chromatogram can be constructed that consists of the 1 st -and 2 nd -dimensional retention times. Breath analysis with a commercial 2D GC instrument has been used for detection of diseases such as cancer, tuberculosis and human volatome [28][29][30] . Unfortunately, the existing commercial 2D GC systems are very bulky and expensive and require trained personnel.…”

Rapid breath analysis for acute respiratory distress syndrome diagnostics using a portable two-dimensional gas chromatography device

“…VOC analytes are subject to two independent separation processes, first by their vapor pressures in the 1st-dimensional column and then by their polarities in the 2nd-dimensional column. It has also been used for detection of diseases such as cancer, tuberculosis, and human volatome [39][40][41]. Due to the bulky size and the long turn-around times, GC-MS and comprehensive 2D GC are not suitable for POC applications and cannot be used to continuously monitor the subject to detect dynamic changes.…”

PSEUDOMONAS AERUGINOSAVOLATILOME CHARACTERISTICS AND ADAPTATIONS IN CHRONIC CYSTIC FIBROSIS LUNG INFECTIONS

“…For the development of a breath test for tracking infections in situ, it will be necessary to utilize culture models that are more reflective of the lung (94)(95)(96)(97) and to collect ex vivo and in vivo infection volatilomes (25,75,98). The utility of breath for tracking chronic lung infections is being demonstrated in tuberculosis lung infection models (26), and therefore we anticipate that the development of a breath-based diagnostic for tracking P. aeruginosa chronic lung infections is feasible. It will also be important to ensure that the P. aeruginosa volatiles we have identified are detectable in breath.…”

“…First, breath provides a non-invasive way of sampling the entire ventilated lung, a limitation of both sputum and bronchoalveolar lavage fluid that leads to delayed diagnosis of new infections, or the detection of infection phenotype changes (16,(21)(22)(23)(24). Second, breath sampling captures metabolic information about the pathogens in situ, eliminating the need for microbial enrichment steps and speeding the time-todiagnosis by days to weeks (25,26). Additionally, in situ metabolic measurements provide information on the physiology of the pathogens in the context of disease versus the context of the lab.…”