Abstract: Abstract： Objective To analyze the clinical characteristics and risk factors for adult community-acquired pneumonia (CAP) caused by Gram-negative bacilli in Tangshan, and provide reference for the early identification of Gram-negative bac⁃ teria CAP and the clinical use of antibiotics. Methods Data of retrospective general information, physical examination, aux⁃ iliary examination and pathogen were collected in patients with CAP in respiratory department from 6 hospitals in Tangshan between October 2011 to September 2012. According to the above data, the prognosis of patients with the team score (PORT) was calculated. The sputum samples were isolated for pathogen identification. Univariate logistic regression analysis and multivariate logistic regression analysis were performed for risk factors of Gram-negative bacilli. Results A total of 195 strains were isolated from 172 (32.45%) patients in 530 patients with CAP. There were 154 strains of Gram-negative ba⁃ cilli (78.97%) and 41 strains of Gram-positive bacteria (21.03%) in 195 bacterial strains. Univariate logistic regression anal⁃ ysis showed the possible risk factors of Gram-negative bacilli in patients with CAP including age≥65 years old, using antibi⁃ otics before hospitalization, basic diseases, cerebrovascular disease, malnutrion, white blood cell abnormal, neutrophilcount＜ 1 ×109/L, PORT classification≥Ⅲ, total bilirubin＞ 17.1 μmol/L and blood urea nitrogen＞ 7.1 mmol/L. Multivariate logistic regression analysis showed the independent risk factors of Gram-negative bacilli in patients with CAP including us⁃ ing antibiotics before hospitalization (OR = 2.327, 95% CI 1.453 -3.725), white blood cell abnormal (OR = 2.904, 95% CI 1.879- 4.490), PORT classification≥Ⅲ (OR = 3.839, 95% CI 2.427 -6.071), and blood urea nitrogen elevated (OR = 4.133, 95% CI 2.585 -6.606). Conclusion Clinical empirical anti-infection treatment should consider the risk factors including using antibiotics before hospitalization, white blood cell abnormal, PORT classification≥Ⅲ and blood urea nitrogen＞ 7.1 mmol/L in patients with susceptible to Gram-negative bacteria infection.

Key words: pneumonia, Gram- negative bacteria, opportunistic infections, risk factors, adult, community acquired pneumonia, Tangshan