ABSTRACT
OBJECTIVE To study the prevalence of atypical pathogens in patients with community acquired pneumonia(CAP) and the distribution of serotypes of Legionella pneumophilia.METHODS A prospective study was performed on 257 consecutive adult patients with CAP between Dec 2003 and Nov 2004.Antibodies of the paired serum samples to Mycoplasma pneumoniae,Chlamydia pneumoniae and Legionella pneumophilia serotypes 1 to 14 were detected.RESULTS The etiology of CAP was identified in 82(31.9%) patients.The distribution of causal agents was as follows:M.pneumoniae 63(24.5%),C.pneumoniae 17(6.6%),and L.pneumophilia 11(4.28%).Serotype 12 of L.pneumophilia was the predominant one,responsible for 21.8%(56/257).CONCLUSIONS Atypical pathogens especially M.pneumoniae have an important role in CAP;serotype 12 of L.pneumophilia is the predominant one in northern area of China.