Etiology and antimicrobial resistance of community-acquired pneumonia in adult patients in China.

Appropriate antimicrobial therapy of community-acquired pneumonia (CAP) is mainly based on the distribution of etiology and antimicrobial resistance of major pathogens. We performed a prospective observational study of adult with CAP in 36 hospitals in China.Etiological pathogens were isolated in each of the centers, and all of the isolated pathogens were sent to Zhongshan Hospital for antimicrobial susceptibility tests using agar dilution.A total of 593 patients were enrolled in this study, and 242 strains of bacteria were isolated from 225 patients. Streptococcus pneumoniae (79/242, 32.6%) was the most frequently isolated pathogen, followed by Haemophilus influenzae (55/242, 22.7%) and Klebsiella pneumoniae (25/242, 10.3%). Totally 527 patients underwent serological tests for atypical pathogens; Mycoplasma pneumoniae and Chlamydia pneumoniae infections were identified in 205 (38.9%) and 60 (11.4%) patients respectively. Legionella pneumophila infections were identified in 4.0% (13/324) of patients. The non-susceptibility rate of isolated Streptococcus pneumoniae to erythromycin and penicillin was 63.2% and 19.1% respectively. Six patients died from the disease, the 30-day mortality rate was 1.1% (6/533).The top three bacteria responsible for CAP in Chinese adults were Streptococcus pneumonia, Haemophilus influenza and Klebsiella pneumonia. There was also a high prevalence of atypical pathogens and mixed pathogens. The resistance rates of the major isolated pathogens were relatively low except for the high prevalence of macrolide resistance in Streptococcus pneumoniae.