Bacteriology and Inflammation in Bronchiectasis (BISER)

Bronchiectasis is a chronic disease arises from progressive airway inflammation and infection. Pro-inflammatory mediators, the products of activated neutrophils recruited to the inflamed sites, are released in bronchiectatic airways and mediate cascades of neutrophil infiltration. This suggests that bacterial infection plays a pivotal role in the neutrophil-derived inflammation leading to the vicious cycle that perpetuates the development of airway destruction and might result in acute exacerbation. Treatments targeting at bacterial infection is therefore necessary, particularly for those with acute exacerbation of bronchiectasis.

Although short- and long-term administration of antibiotics have been evidenced to markedly suppress bacterial colonization and inflammatory indices, the roles that potent antibiotics play in patients with exacerbation of bronchiectasis are unclear. The assessment of bacterial infection and sputum and systemic inflammation during steady-state, acute exacerbation and recovery from exacerbation of bronchiectasis may clinically shed light on and indicate the efficacy of antibiotic treatments.

Furthermore, a subgroup of patients may experience the acute exacerbation that may stem from non-bacterial pathogens. There has been a dire need to compare the changes in sputum bacterial load and inflammatory indices based on sputum bacteriology. This may help uncover the mechanism of different responses to antibiotic treatment in patients who had varying bacteriologic profiles.

Unlike assessment of chronic obstructive pulmonary disease, few clinical indices for appraisal of onset of exacerbation and efficacy of treatments are available. Of these, the 24-hour sputum volume, microbial clearance, C-reactive protein (CRP) and St George's Respiratory Questionnaire have been validated. In the present study, we employed sputum bacteriology and inflammatory indices, including the aforementioned parameters, for assessment.