Identification of airway bacterial colonization by an electronic nose in Chronic Obstructive Pulmonary Disease

Abstract

Airway bacterial colonization by potentially pathogenic microorganisms occurs in a proportion of patients with Chronic Obstructive Pulmonary Disease (COPD). It increases airway inflammation and influences outcomes negatively. Yet, its diagnosis in clinical practice is not straightforward. The electronic nose is a new non-invasive technology capable of distinguishing volatile organic compound (VOC) breath-prints in exhaled breath. We aim to explore if an electronic nose can reliably discriminate COPD patients with and without airway bacterial colonization. We studied 37 clinically stable COPD patients (67.8 ± 5.2 yrs, FEV1 41 ± 10% ref.) and 13 healthy controls (62.8 ± 5.2 yrs, FEV1 99 ± 10% ref.). The presence of potentially pathogenic microorganisms in the airways of COPD patients (n = 10, 27%) was determined using quantitative bacterial cultures of protected specimen brush. VOCs breath-prints were analyzed by discriminant analysis on principal component reduction, resulting in cross-validated accuracy values. Area Under Receiver Operating Characteristics (AUROC) was calculated using multiple logistic regression. Demographic, functional and clinical characteristics were similar in colonized and non-colonized COPD patients but their VOC breath-prints were different (accuracy 89%, AUROC 0.92, p > 0.0001). Likewise, VOCs breath-prints from colonized (accuracy 88%, AUROC 0.98, p < 0.0001) and non-colonized COPD patients (accuracy 83%, AUROC 0.93, p < 0.0001) were also different from controls. An electronic nose can identify the presence of airway bacterial colonization in clinically stable patients with COPD.