Bronchoscopic detection of aspiration in patients with bronchiectasis and Mycobacterium avium complex pulmonary infection

Rationale

To investigate whether gastroesophageal reflux with laryngopharyngeal reflux and aspiration play a role in the pathogenesis of bronchiectasis and Mycobacterium avium complex (MAC) pulmonary infection.

Methods

In this prospective case-control study, subjects included 31 patients with bronchiectasis undergoing bronchoscopy to investigate suspected MAC infection and 9 control subjects undergoing bronchoscopy for alternative reasons. Patients drank 45 mL of FD&C Blue #1 mixed with 200 mL of tap water the night prior to bronchoscopy. During bronchoscopy, the bronchial mucosa was inspected for the presence of blue dye staining. Bronchoalveolar lavage (BAL) samples were obtained from the most affected segments on CT scan and were cultured for mycobacteria and assayed for pepsin and bile acids. Gastric aspirate samples were obtained for mycobacterial culture.

Results

93.8% of patients with confirmed pulmonary MAC infection and 91.7% of patients with evidence of bronchiectasis by CT scan, but negative mycobacterial cultures, had blue dye staining of the bronchial mucosa vs. 11.3% of control patients (p < 0.001). Areas of abnormality on CT correlated with airways demonstrating blue staining by bronchoscopy in 100% of MAC patients and 90.9% of patients with bronchiectasis and negative mycobacterial cultures. MAC patients had higher median BAL pepsin levels compared to combined MAC negative patients (subjects with bronchiectasis and negative mycobacterial cultures and true controls), 5.4 ng/mL vs. 3.4 ng/mL (p = 0.019). 78.6% of MAC patients vs. 26.3% of combined MAC negative patients had BAL bile acid concentrations of >/= 0.493 uM (p = 0.005). There was no significant difference in age, supraglottic index, reflux symptoms, gastric pH, or proton pump inhibitor use between the MAC positive vs. MAC negative patients. 42.8% of patients with growth of MAC on BAL also had growth of MAC in the gastric aspirate.

Conclusions

Reflux and aspiration of gastric contents into the airways show a strong association with bronchiectasis and may be associated with MAC pulmonary disease. The novel method introduced in this study of drinking blue dye the evening prior to bronchoscopy should be utilized in the evaluation of infectious and inflammatory lung diseases in which aspiration may play a role.