Dynamic Study Of The Fine Pathogenic Spectrum Of Bronchiectasis

Background:The colonization of pathogenic bacteria and chronic infection are important factors in the progression of bronchiectasis.Most of studies have targeted sputum as the sample,while alveolar lavage fluid can reflect the lower respiratory tract pathogens in bronchiectasis more accurately.And the latest development of pathogen detection technology m NGS has greatly improved the efficiency of pathogen detection.Objectives:To study the distribution of the pathogenic microorganisms with bronchiectasis and the situation of the peculiar pathogens infection.To investigate the correlation between pathogens and clinical features,and to study the characteristics of microecology in the acute exacerbation and stabilization periods.Methods:A prospective,observational study was conducted on patients with bronchiectasis in the The First Affiliated Hospital of Guangzhou Medical University from December 2020 to August 2022.Alveolar lavage fluid was retrieved by fibrinoscopy in acute exacerbation and in stable for m NGS,validated and compared by 16 s r RNA sequencing,and traditional culture methods,serological tests,and pulmonary function measurements were performed.And clinical data were collected.Results:A total of 171 patients(52.6 ± 14.6 years,123 females)with bronchiectasis and 6healthy controls were enrolled.The pathogens detected by m NGS were excluded from the list of colonizing,contaminating and background organisms,and the pathogens were considered to be strictly pathogenic in combination with the clinical picture(elevated PCT/CRP and improvement after treatment with sensitive antibiotics).The distribution of pathogenic bacteria detected in the lower respiratory tract during acute exacerbation of bronchiectasis was Pseudomonas aeruginosa,Haemophilus influenzae,NTM,Aspergillus,Virus,Nocardia,Staphylococcus aureus,and Acinetobacter baumannii,in descending order.The distribution of pathogenic bacteria was correlated with age(P < 0.05).Nocardia was mainly distributed in people under 60 years of age,while Pseudomonas aeruginosa,NTM,and Aspergillus accounted for a larger proportion in people over 60 years of age.P.aeruginosa colonized/infected patients with bronchiectasis had lower FEV1 values than those without P.aeruginosa colonization/infection(1.2800 vs.2.0250,P < 0.05).NTM in bronchiectasis is common in women;low body mass index;and patients with a previous history of tuberculosis infection.There was no significant difference in microecologicalα-diversity and β-diversity between acute exacerbation and stable branched amplification.Conclusion:1.Pseudomonas aeruginosa(45%),followed by Haemophilus influenzae 10%,NTM(8%),Aspergillus(8%),viruses(6%),Nocardia(5%),Staphylococcus aureus(3%),and Acinetobacter baumannii(2%)were the predominant pathogens in patients with bronchiectasis.2.Pseudomonas aeruginosa was associated with decreased FEV1 values of pulmonary function,and Haemophilus influenzae,NTM,and Aspergillus have not been found to be associated with pulmonary function.3.The distribution of pathogenic bacteria was different in patients of different ages.Nocardia was mainly distributed in people under 60 years old,while Pseudomonas aeruginosa,NTM,and Aspergillus accounted for a larger proportion in people over 60 years old.4.NTM in bronchiectasis is common in women;low body mass index;and patients with a previous history of tuberculosis infection.5.There was no significant difference in microecological α-diversity andβ-diversity between acute exacerbation and stable bronchiectasis.m NGS can provide more information about the species level than 16 r RNA sequencing.