Investigation Of Chalamydia Pneumoniae Infection In Hospitalized Children

[ Background and objective]Chlamydia pneumoniae (C.pn), first described in 1989, is a common cause of infection. It was found in healthy people, in upper respiratory tract illness as well as lower respiratory tract disease including bronchitis and community-acquired pneumonia. More than 50% of adults had specific antibodies to C.pn. It was one of the main pathogen of community-acquired pneumonia. The study of C.pn in our country started in 1995. It is not clear about its infective rate and prevalence in children. In this study, we studied the infection of C.pn in hospitalized children by the method of ELISA , and evaluated its effect on children's respiratory tract infections.From November 2003 to December 2004, 1314 hospitalized children with respiratory tract diseases and some with other system disease were included in this investigation. 821 boys and 493 girls aged 52 days - 14 years old, the mean age was 4 y and the median age was 4.2 y.The IgM and IgG antibodies of C.pn were evaluated with ELISA..-All data were evaluated by SPSS 10.0. Variance analyses was used to detect the inter-group difference, x2-test was applied to compare counting data. P-value < 0.05 was considered significantly.[Results]C.pn infection could occur in different season and had the epidemic characteristic. The disease was more common from Jan. to June in 2004. We found that CP-IgM positive was more in the girl groups than in the boy groups of 1-3 y and 3-5 y ,there was not difference between in the girl and boy groups of 0-1 y and 5-14 y. Some patients (15.2%) were CP-IgM and CP-IgG positive. CP-IgM positive appeared mainly in the patients with respiratory tract infection. The rate of CP-IgM positive was higher in bronchitis than in other respiratory tract infection disease. Infection of mycoplasma pneumoniae (Mpn) was often detected in the patients with CP-IgM positive. The C.pn single infection is less in upper respiratory tract infection than in lower respiratory tract infection. The C.pn infection in lower respiratory tract had high rate of wheeze(26.5%). The pneumonia patients infected with C.pn were sensitive to azithromycin. It was different on the chest X-ray appearance in the different age groups (The 0-5 y group appeared with bilateral lung changes, the 5-14 y group appeared with the lateral lung changes.[Conclution]1.Chlamydia pneumoniae is the common pathogen of children's respiratory tract disease.2. C.pn infection could occur in different season and had the epidemic characteristic.3. The children could be infected by C.pn at any ages .4. Mixing infection was common in C.pn infection.5.The pneumonia patients infected with C.pn were sensitive to azithromycin.