There are a large number of patients with chronic obstructive pulmonary disease (COPD) and bronchiectasis in China, which are chronic respiratory diseases with high morbidity and mortality. Bronchiectasis-COPD overlap syndrome (BCOS) is a special clinical subtype, but it is easy to be ignored. Infection often contributes to their acute exacerbation, but related etiological studies are relatively scarce.

To analyze the distribution and drug resistance characteristics of pathogens in bronchiectasis patients without and with COPD, and to compare the differences between them.So as to provide references for rational use of antimicrobial agents.

A total of 584 patients with bronchiectasis who were hospitalized in the Department of Pulmonary and Critial Care Medicine of Ma'anshan People's Hospital from January 2016 to January 2023 were enrolled. The patients were divided into two groups according to whether they combined with COPD or not: BE group (335 cases without COPD) and BCOS group (249 cases with COPD). A retrospective analysis was performed on the composition, antimicrobial susceptibility results and changes of pathogens on patients, and analyze the difference of distribution and drug resistance between the two groups.

A total of 299 strains were isolated from 584 patients with bronchiectasis, 146 strains from BE group, among them, Gram-negative bacilli 87 strains (59.59%), Gram-positive bacteria 3 strains (2.05%), Mycobacterium 9 strains (6.16%), Fungus 47 strains (32.19%). Meanwhile, 153 strains from BCOS group, among them, Gram-negative bacilli 80 strains (52.29%), Gram-positive bacteria 1 strains (0.65%), Mycobacterium 2 strains (1.31%), Fungus 70 strains (45.75%). The composition ratio of Candida albicans were significantly higher in BCOS group than BE group (χ²=5.274, P=0.022). The resistance rates of Pseudomonas aeruginosa to imipenem in BE group and BCOS group were 10.64%, 25.53%, piperacillin tazobactam 6.98%, 15.91%, ciprofloxacin 12.77%, 21.28%, amicacin 2.13%, 2.13%, respectively. The resistance rates of Klebsiella pneumoniae to imipenem were 0, 14.29%, piperacillin tazobactam 0, 14.29%, ciprofloxacin 15.38%, 35.71%, amikacin 0, 7.14%, respectively. The resistance rate of Pseudomonas aeruginosa to ampicillin/sulbactam in BCOS group was significantly lower than that in BE group (P=0.026). The isolation rates of ESBLs-producing enterobacteriaceae (χ²=4.357, P=0.037) and carbapenem-resistant Pseudomonas aeruginosa in BCOS group were higher than BE group (χ²=5.593, P=0.018). From 2016 to 2022, the isolation strains of Pseudomonas aeruginosa in patients with bronchiectasis was the highest, and showed a trend of first decreasing and then increasing. The isolation strains of Klebsiella pneumoniae increased significantly in 2021 and 2022, second only to Pseudomonas aeruginosa. The isolation strains of Mycobacterium from 2020 to 2022 and Aspergillus from 2021 to 2022 showed an upward trend.

As a special phenotype, BCOS has its own characteristics of pathogen distribution and drug resistance, which deserves attention. Pseudomonas aeruginosa is the most common pathogen isolated from patients with bronchiectasis and BCOS currently. In recent years, the isolation strains of Klebsiella pneumoniae is second only to Pseudomonas aeruginosa. The detection of Mycobacterium and Aspergillus has significantly higher than before, which should be taken seriously, especially in BE patients.

我国慢性阻塞性肺疾病（简称慢阻肺）及支气管扩张症（简称支扩）患者数量庞大，均为高发病率、高病死率的慢性呼吸系统疾病。支气管扩张症-慢性阻塞性肺疾病重叠综合征（BCOS）作为一种特殊临床亚型虽常见但易被忽略。感染常是其急性恶化的诱因，但相关病原学研究相对匮乏。

分析单纯性支气管扩张症（BE）与BCOS患者病原菌分布、耐药性特点，比较两者差异。为临床合理使用抗菌药物提供参考。

选取2016年1月—2023年1月在马鞍山市人民医院呼吸与危重医学科住院的支扩患者584例为研究对象，根据是否合并慢阻肺将患者分为两组：BE组（未合并慢阻肺，335例）和BCOS组（合并慢阻肺，249例）。回顾性分析患者病原菌构成、药敏结果及变迁，分析两组病原菌分布及耐药性差异。

584例支扩患者共分离299株病原菌，BE组分离病原菌146株，其中革兰阴性菌87株（59.59%），革兰阳性菌3株（2.05%），分枝杆菌9株（6.16%），真菌47株（32.19%）；BCOS组分离病原菌153株，其中革兰阴性菌80株（52.29%），革兰阳性菌1株（0.65%），分枝杆菌2株（1.31%），真菌70株（45.75%）；BCOS组患者白色念珠菌构成比高于BE组（χ²=5.274，P=0.022）。两组铜绿假单胞菌耐药率分别为：亚胺培南10.64%、25.53%，哌拉西林他唑巴坦6.98%、15.91%，环丙沙星12.77%、21.28%，阿米卡星2.13%、2.13%；两组肺炎克雷伯菌耐药率分别为：亚胺培南0、14.29%，哌拉西林他唑巴坦0、14.29%，环丙沙星15.38%、35.71%，阿米卡星0、7.14%；BCOS组铜绿假单胞菌对氨苄西林舒巴坦耐药率低于BE组（P=0.026）。BCOS组患者产超广谱β内酰胺酶肠杆菌科（χ²=4.357，P=0.037）及耐碳青霉烯类铜绿假单胞菌分离率均高于BE组（χ²=5.593，P=0.018）。2016—2022年支扩患者分离铜绿假单胞菌株数均最高，呈先降后升趋势；分离肺炎克雷伯菌株数在2021、2022年明显升高，仅次于铜绿假单胞菌；2020—2022年分离分枝杆菌株数及2021—2022年分离曲霉菌株数均呈上升趋势。

BCOS作为一种特殊表型，其病原菌分布、耐药性有其自身特点，值得关注。铜绿假单胞菌目前是BE及BCOS患者常见分离致病菌，近年来分离肺炎克雷伯菌株数仅次于铜绿假单胞菌。分离分枝杆菌、曲霉菌株数较前亦明显上升，应引起重视，尤其是BE患者。