Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disease characterized by incomplete reversible airflow limitation, small airway obstruction and alveolar structural damage. About 3 million patients die from COPD every year around the world. The prevalence of COPD in Chinese people over the age of 40 is as high as 12 % and has risen by 50 % in the past nine years.~Acute exacerbation is the leading cause of death in patients with COPD , and accounts for a majority of expenditure of COPD management. The colonization of potential pathogenic bacteria in the lower respiratory tract is an important cause of the acute exacerbation especially in patients with moderate and severe COPD.~Some clinical studies show that aerosol inhaled antibiotics is promising in reducing acute exacerbation, but these exploratory studies have some defects so that they can't back up for the clinical application of aerosol inhaled antibiotics. Amikacin, a kind of aminoglycosides, is sensitive to the common pathogens of acute exacerbation of COPD in China. Therefore it is necessary to carry out a clinical trial to verify its efficacy and safety in pathogen decolonization and prevention of acute exacerbation.~In addition, owing to bacterial resistance and insufficient antibiotics concentration in lower respiratory tract, developing new antibacterial materials is necessary. Oral probiotics is an another way to regulate the bacterial load and inflammatory response in lower respiratory tract, which has been proven to effectively prevent acute exacerbation in cystic fibrosis and childhood asthma. Likewise, airway bacterial burden and inflammation are two main mechanisms of acute exacerbation in COPD. Hence, considering its convenience and safety of oral probiotics, we perform a trial to make clinical evaluation for it.~What's more, influenza and streptococcus pneumoniae vaccines are separately recommended for patients with COPD in the Global Initiative for Chronic Obstructive Pulmonary Disease(GOLD), but there have been no studies on the effects of combined vaccination on bacterial decolonization in lower respiratory tract or on the prevention of acute exacerbation.~Effects of these above methods on the decolonization of potential pathogenic bacteria in lower respiratory tract and the inflammatory reaction are not clear. Therefore, we plan to perform a multi-center, randomized, controlled trial to study the efficacy and safety of oral probiotics, aerosol inhaled amikacin or combined vaccination to decolonize bacteria in lower respiratory tract and prevent acute exacerbation of COPD.
The colonization of potential pathogenic bacteria in lower respiratory tract is thought to be accountable for acute exacerbation in subjects with moderate to severe COPD. However, there is no accepted therapy for patients with COPD to remove the colonized bacteria in lower respiratory tract. Therefore, we plan to perform a multi-center, randomized, controlled trial to study the efficacy and safety of oral probiotics, aerosol inhaled amikacin or combined vaccination to decolonize bacteria in lower respiratory tract and prevent acute exacerbation of COPD.