Objective To analyze the distribution and drug resistance of pathogenic bacteria by sputum culture in chronic obstructive pulmonary disease (COPD) patients complicated with pneumonia so as to provide a theoretical basis for clinical rational drug use.

Methods The clinical data of 507 COPD patients complicated with pneumonia were retrospectively analyzed. Sputum specimens were collected and cultured to determine the distribution of pathogenic bacteria, and drug sensitivity tests were performed to analyze the resistance of pathogenic bacteria. The degree of dyspneamodified Medical Research Council Respiratory Questionnaire (mMRC) score and quality of lifeChronic obstructive Pulmonary Disease Assessment Test (CAT) score were compared between patients using medication based on drug susceptibility test results and usage of empiric medication of patients.

Results The qualified sputum specimens of 507 COPD patients combined with pneumonia were cultured and 152 pathogenic strains were isolated, including 13(8.55%) Gram-positive strains, 75(49.34%) Gram-negative strains and 64 fungal strains(42.11%). Drug sensitivity tests showed that the drug-resistant strains among the Gram-negative bacteria were mainly Klebsiella pneumonia, Pseudomonas aeruginosa, and Acinetobacter baumannii, and the three pathogenic bacteria had the highest resistance rates to ampicillin (100.00%). Their resistance rate to ceftriaxone, cefzolin and cefepime were not less than 50.00%, and the resistance rate of Klebsiella pneumoniae to amikacin was 0%. Only Staphylococcus haemolyticus showed resistance among gram-positive bacteria, with the highest resistance rate to penicillin (100.00%), while resistance rates to benzathine, imipenem, clindamycin, and ampicillin were higher than 65.00%. According to the results of drug sensitivity test, the mMRC score and CAT score of patients with medication were lower than those of patients with empirical medication (P < 0.05).

Conclusion The infectious organisms of patients with COPD combined with pneumonia are mainly Gram-negative bacteria and fungi, and the resistance of different pathogenic bacteria to antimicrobial drugs is obviously different. Sputum culture and drug sensitivity test of patients' sputum samples can guide clinicians to use antibiotics rationally, thereby helping patients to improve respiratory function and quality of life.