To investigate the distribution of pathogenic bacteria in community-acquired pneumonia among the elderly population, to construct a risk assessment model for high-risk groups of community-acquired pneumonia, and to provide a basis for clinical prevention and control of pneumonia.

A total of 163 elderly patients with community-acquired pneumonia who were hospitalized in Chongqing Fuling Hospital, School of Medicine, from January 2020 to January 2025 were included as the pneumonia group, and another 180 elderly people with normal physical examinations during the same period were selected as the control group. By comparing the baseline data of the two groups of patients, logistic multivariate analysis was used to identify the independent risk factors for the occurrence of community-acquired pneumonia in the elderly. Based on the results of the factor analysis, a nomogram prediction model was constructed. The model’s efficacy was evaluated using the receiver operating characteristic (ROC) curve, calibration curve, and Hosmer-Lemeshow goodness-of-fit test.

A total of 172 pathogenic bacteria were isolated from 163 patients with community-acquired pneumonia, with Candida albicans (41.10%) and Klebsiella pneumoniae (31.29%) accounting for the highest proportion. The results of the logistic analysis showed that smoking history (OR=1.971, 95%CI: 1.396 - 2.783), cerebrovascular disease (OR=1.300, 95%CI: 1.013 - 1.668), anemia (OR=1.281, 95%CI: 1.014 - 1.618), liver and kidney dysfunction (OR=2.037, 95%CI: 1.008 - 4.118), septic shock (OR=2.299, 95%CI: 1.074 - 4.922), consciousness disorder (OR=1.635, 95%CI:1.074 - 2.488), animal breeding (OR=1.901, 95%CI: 1.364 - 2.648), and dust exposure (OR=1.478, 95%CI: 1.048 - 2.085) were all independent risk factors for community-acquired pneumonia in the elderly（P<0.05）. The ROC curve of the nomogram showed that the AUC=0.710 (95%CI: 0.661 - 0.759), the sensitivity was 0.702, and the specificity was 0.813. The Hosmer-Lemeshow test result showed:P=0.36 (P > 0.05).

Smoking history, cerebrovascular disease, anemia, liver and kidney dysfunction, etc. are all independent risk factors for community-acquired pneumonia in the elderly. Early prevention and control of these risk factors should be strengthened to reduce the risk of pneumonia occurrence.