Abstract: OBJECTIVE To explore the distribution of pathogens and the expression levels of serum N-terminal brain natriuretic peptide (NT-proBNP), matrix metalloproteinases (MMPs) and inflammatory factors in the elderly patients with chronic heart failure. METHODS A total of 120 heart failure patients who were complicated with pulmonary infection and treated in Nanjing Chest Hospital from Jan 2020 to Dec 2022 were assigned as the infection group, meanwhile, 120 patients who had simple heart failure were assigned as the non-infection group, and 120 healthy elderly people who received physical examination were chosen as the control group. The sputum specimens were collected from the patients of the infection group, pathogens were cultured and identified. The expression levels of serum NT-proBNP, MMPs and inflammatory factors were detected and compared among the three groups. RESULTS Totally 187 strains of pathogens were isolated from the sputum specimens of the patients in the infection group, 130 (69.52%) of which were gram-negative bacteria, 50 (26.74%) were gram-positive bacteria, and 7 (3.74%) were fungi. Escherichia coli was the predominant species of the gram-negative bacteria; Streptococcus pneumoniae was dominant among the gram-positive bacteria; Candida albicans was dominant among the fungi. The levels of serum MMPs, NT-proBNP and inflammatory factors procalcitonin(PCT), tumor necrosis factor-α(TNF-α), interleukin(IL)-1β, IL-6 of the infection group were higher than those of the non-infection group and the control group. CONCLUSION The gram-negative bacteria are dominant among the pathogens isolated from most of the elderly heart failure patients complicated with pulmonary infection. The levels of MMPs, NT-proBNP and inflammatory factors of the patients with infection are elevated.