Using the Electronic Nose to Identify Airway Infection during COPD Exacerbations

Abstract

BackgroundThe electronic nose (e-nose) detects volatile organic compounds (VOCs) in exhaled air. We hypothesized that the exhaled VOCs print is different in stable vs. exacerbated patients with chronic obstructive pulmonary disease (COPD), particularly if the latter is associated with airway bacterial infection, and that the e-nose can distinguish them.MethodsSmell-prints of the bacteria most commonly involved in exacerbations of COPD (ECOPD) were identified in vitro. Subsequently, we tested our hypothesis in 93 patients with ECOPD, 19 of them with pneumonia, 50 with stable COPD and 30 healthy controls in a cross-sectional case-controlled study. Secondly, ECOPD patients were re-studied after 2 months if clinically stable. Exhaled air was collected within a Tedlar bag and processed by a Cynarose 320 e-nose. Breath-prints were analyzed by Linear Discriminant Analysis (LDA) with “One Out” technique and Sensor logic Relations (SLR). Sputum samples were collected for culture.ResultsECOPD with evidence of infection were significantly distinguishable from non-infected ECOPD (p = 0.018), with better accuracy when ECOPD was associated to pneumonia. The same patients with ECOPD were significantly distinguishable from stable COPD during follow-up (p = 0.018), unless the patient was colonized. Additionally, breath-prints from COPD patients were significantly distinguished from healthy controls. Various bacteria species were identified in culture but the e-nose was unable to identify accurately the bacteria smell-print in infected patients.ConclusionE-nose can identify ECOPD, especially if associated with airway bacterial infection or pneumonia.

Identification and Antibiotic‐Susceptibility Profiling of Infectious Bacterial Agents: A Review of Current and Future Trends

“…[118] It also discriminated the VOCs from patients with pneumonia, from the VOCs of healthy controls, with 100% accuracy. [119] Finally, the same device allowed to identify the bacterial species in 72% of patients affected with sinusitis. [120] A prospective cross sectional proof-of-concept study was performed for the GC-IMS E-nose in the analysis of VOCs from exhaled breath from patients and to distinguish bacterial from viral respiratory tract infections.…”

“…Selected examples of future technologies for pathogen identification (ID) and antimicrobial susceptibility testing (AST). No CA A [114,119,[121][122][123][124] Flow cytometry Follow the viability of microorganisms, after exposure to antibiotics using dyes that do not permeate the cell walls of healthy bacteria 2-3 h No Yes POP A [140,141] IMC (isothermal microcalorimetry)…”

Identification of Pseudomonas aeruginosa and airway bacterial colonization by an electronic nose in bronchiectasis

“…Exclusions were: patients with age less than 18 years; unable to give informed consent or with other respiratory diseases such as CF, active allergic bronchopulmonary aspergillosis, active non-tuberculous mycobacterial infection or pulmonary fibrosis with traction bronchiectasis, as well as patients receiving immunoglobulin replacement therapy or chronic systemic corticosteroid treatment. Sample size was calculated as described in previous studies [17,18].…”

“…Furthermore, several studies have shown that the e-nose is also able to detect respiratory infections. In COPD, the e-nose has successfully distinguished patients with and without airway bacterial infection during clinical stability [17] and acute exacerbations [18]. Some studies have suggested that specific bacteria such as P. aeruginosa, may produce distinguishable VOC [19][20][21].…”

Volatile organic compound detection as a potential means of diagnosing cutaneous wound infections

“…The Cyranose 320 and E50835 electronic nose devices have been utilized to differentiate between P. aeruginosa, S. aureus, and E. coli isolates based on VOC patterns from the headspace. 81,[111][112][113] However, it does not provide details regarding the individual volatile compounds emitted by the bacteria.…”