Objective  To investigate the sites of infection, bacterial species and the levels of brain natreuretic peptide (BNP) in chronic heart failure complicated with infection patients with New York Heart Association (NYHA) grade Ⅰ to Ⅳ.

  Methods  One hundred and two patients with chronic heart failure complicated with infection were selected as infection group, and the infection sites and bacterial species were studied. Another 102 patients with simple chronic heart failure admitted to hospital during the same period were selected as uninfection group. The difference of BNP content between the two groups was compared. The levels of BNP before and after infection were compared in the uninfection group during hospitalization, and BNP increment trend before and after infection was analyzed.

  Results  The body temperature, hypersensitivity C-reactive protein, interleukin-6, procalcitonin and BNP in the infection group were significantly higher than those in the uninfection group (P < 0.05). In the infection group, the main infection site was lower respiratory tract, and the main pathogenic bacteria was Pseudomonas aeruginosa; the BNP level after infection was significantly higher than that before infection in the uninfection group (P < 0.05). After infection, the BNP of different NYHA classification showed an increasing trend.

  Conclusion  The infection site of patients with chronic heart failure is mainly in the lower respiratory tract, and Pseudomonas aeruginosa infection is most common. Infection can increase the BNP content in patients with heart failure. The influence of infection on BNP should be fully considered to evaluate the prognosis of heart failure when using BNP to assist diagnosis and treatment.