[Respiratory pathogen spectrum in pulmonary exacerbation of bronchiectasis in adults and its association with disease...

Objective: To determine the pattern of respiratory pathogens at bronchiectasis exacerbation and its associations with disease severity. Methods: A total of 119 steady-state bronchiectasis patients [42 males, 77 females, age range 19 to 74 years, mean age (45±14)years], diagnosed by a compatible history combined with evidence of bronchial dilatation on high-resolution computed tomography (HRCT), were recruited prospectively from out-patient clinics in the First Affiliated Hospital of Guangzhou Medical University between September 2012 and March 2013. A comprehensive history taking, radiologic appearance, spirometry, sputum bacterial culture and 16 respiratory viruses in nasopharyngeal swabs and sputum samples by PCR assays were collected at steady-state bronchiectasis. All bronchiectasis patients were followed up one year and assessed for bacteriology, virology and systemic inflammatory indices [including white blood cell, C-reactive protein (CRP), interleukin-6, 8 and tumor necrosis factor-α] during bronchiectasis exacerbation. Results: Fifty-eight bronchiectasis patients [20 males, 38 females, age range 19 to 74 years, mean age (44±14) years] reported 100 exacerbations (1 to 5 exacerbation events per patient) during one year follow-up. Respiratory viruses were found more frequently in sputum and nasal swab during exacerbation [35.0% (35/100) and 39% (39/100)] than those during steady-state in bronchiectasis [sputum: 13.8% (8/58), nasal swab: 8.6% (5/58)] (χ(2)=8.33,χ(2)=13.51; respectively, all P<0.05). The rate of bacterial detection during exacerbation in sputum was 56% (56/100), which was not significantly different compared with those at steady-state (35/58, 60.3%;χ(2)=0.284, P=0.59). Of these respiratory infections, viral-bacterial co-infection accounted for 30% exacerbation events. The most common bacteria and viruses during exacerbation in mild bronchiectasis (n=18, with 25 exacerbation events) were Haemophilus parainfluenzae (4 cases) in sputum and influenza A in nasal swab or sputum (4 cases), respectively. In patients with moderate (n=17, with 29 exacerbation events)-severe bronchiectasis (n=23, with 46 exacerbation events), pseudomonas aeruginosa was the most common bacteria in sputum (35 cases), and the most common respiratory viruses were rhinovirus in nasal swab or sputum (11 cases). In these 100 exacerbation events, patients with bacterial and viral co-infection, pure bacteria infection, pure virus infection, no bacteria and virus infection accounted for 30, 29, 16 and 25 exacerbation events, respectively. And patients with co-infection had higher serum CRP (45±23) mg/L and IL-8 [9.0 (4.4-15.5) ng/L] (F=23.32, F=9.81,respectively; all P<0.05), and increased risk of hospitalization (30% vs. 0] compared with those in non-infectious group(χ(2)=9.0, P=0.003). Conclusions: Pseudomonas aeruginosa, rhinovirus and influenza A were common causative agents of exacerbation in bronchiectasis.In patients with moderate-severe bronchiectasis, pseudomonas aeruginosa was the most common bacterium in sputum, and the most common respiratory virus was rhinovirus in nasal swab or sputum, compared to Haemophilus parainfluenzae in sputum and influenza A in nasal swab or sputum in mild bronchiectasis. Patients with co-infection had more severe systemic inflammatory response and higher risk of hospitalization during exacerbation.