Study On The Etiology Of Community-acquired Pneumonia

ObjectiveTo investigate the etiology of community-acquired pneumonia(CAP) in shanghai area, especially the prevalence of atypical pathogens; to study the Drug-restriction of the causal bacteria in the infection of CAP.MethodsThe patients above 18 years old with CAP from 4 hospitals in Shanghai area were enrolled in the study. Antibody of the paired serum samples to Mycoplasma pneumoniae, Legionella pneumophilia, and Chlamydia pneumoniae were detected. The Pl adhesion gene of Mycoplasma pneumoniae and the 16S ribosome gene specific for Chlamydia pneumoniae were first detected with polymerase chain reaction(PCR). In the reaction, the uracil-DNA-glycosylase (UDG) system was used to prevent contamination from previous amplifications and a specific internal control was added to detect possible inhibitors of the reaction. When the results were positive , the samples were confirmed with the PCR using the primers directed against species-specific sequence of the 16S ribosome gene of Mycoplasma pneumoniae and the 53kDa gene of Chlamydia pneumoniae. Sputum samples were collected for culture, and bacteria were isolated and identified using conventional methods, then the drug sensitive test will be continued. Results247patients above 18years old with CAP were enrolled. Specific pathogens were identified in 128(51.8%) patients. The distribution of causal agents was as follows: Mycoplasma pneumoniae in 39(26. 4%), Chlamydia pneumoniae 17(11. 5%), Legionella pneumophilia 7(4.7%), Haemophilus pneumoniae 23(15.5%), Streptococcus pneumoniae 17(11.5%). In 20(15.6%) patients more than one causal agent were found, among them Mycoplasma pneumoniae was foundin 14 cases with mixed infections. And the prevalence of Mycoplasma pneumoniae was the highest in that of atypical pathogens, it was 61.9%(39/63). Haemophilus pneumoniae and Streptococcus pneumoniae are most causal agents in those of community acquired pneumonia. The prevalence of penicillin resistant Streptococcus pneumoniae(PRSP)was 23. 5%. The resistant rates of Streptococcus pneumoniae to erythromycin, clindamycin ranged from 70. 6%~ 76. 5%., so we must pay attention.83.9%~100% of Haemophilus pneumoniae strains were susceptible to ampicillin, amoxicillin/clavulanic acid, cefaclor, cefprozil, ceftriaxone, azithromycin, ciprofloxacin, levofloxacin, gatifloxacin and moxifloxacin.ConclusionsMycoplasma pneumoniae , Streptococcus pneumoniae , Haemophilus pneumoniae and Chlamydia pneumoniae were the most common bacteria in the etiology of community acquired pneumonia. Streptococcus pneumoniae and Haemophilus pneumoniae remain the most common bacteria. The rate of PRSP was still lower than that of other countries, especially that of countries or areas nearby. Atypical pathogens especially Mycoplasma pneumoniae have an important role in CAP. , and mixed infection should not be ignored.