Abstract: OBJECTIVE To study the inflammatory factors in elderly patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) after infection induced by bacteria like Pseudomonas aeruginosa (PA), and the relationship between virulence genes and drug resistance of PA. METHODS A total of 175 elderly patients with AECOPD admitted to the Second Affiliated Hospital of Shandong University of Traditional Chinese Medicine from Nov. 2018 to Mar. 2021 were selected as the research subjects, among which 85 patients with combined lower respiratory tract bacterial infection were set as bacterial infection group, and the remaining 90 patients without combined lower respiratory tract bacterial infection were set as the non-infection group. The distribution of pathogenic bacteria, and drug resistance of PA were analyzed. The inflammatory factors white blood cell count (WBC), neutrophil (NE), procalcitonin (PCT), C-reactive protein (CRP) in the two groups were compared before and after treatment. Receiver operating characteristic (ROC) curve was used to analyze the diagnostic efficacy of WBC, NE, PCT and CRP in predicting AECOPD complicated with lower respiratory tract bacterial infection, and polymerase chain reaction (PCR) was used to detect the virulence genes exoS and exoU of PA, and the relationship between the virulence genes exoS and exoU and drug resistance was analyzed. RESULTS A total of 107 strains of pathogenic bacteria were cultured in infected patients, among which 93 strains of Gram-negative bacteria accounted for 86.92% and 14 strains of Gram-positive bacteria accounted for 13.08%, mainly including PA, Klebsiella pneumoniae (KPN) and Acinetobacter baunii (AB). The resistance rate of PA to levofloxacin, ciprofloxacin, imipenem and meropenem was less than 30%. The WBC, NE, PCT and CRP in the infection group were higher than those in the non-infection group (P<0.05). After treatment, WBC, NE, PCT and CRP in bacterial infection group were lower than those before treatment (P<0.05). ROC curve analysis showed that WBC, NE, PCT and CRP levels had a high value in predicting lower respiratory tract bacterial infection in elderly patients with AECOPD (P<0.05). A total of 8 strains (24.24%) of multi-drug resistant bacteria were detected in 33 PA strains. CONCLUSION The levels of WBC, NE, PCT and CRP were highly expressed in elderly patients with AECOPD complicated with lower respiratory tract infection, which had a high predictive value for AECOPD complicated with lower respiratory tract infection. PA had a high rate of exoS carriage and a low rate of exoU carriage in virulence genes, but exoU had a high resistance to carbapenems and fluoroquinolones.