Detection And Analysis For Chlamydophila Pneumoniae In Peripheral Blood Of Respiratory Tract Infection Patients

Objective:To investigate the Chlamydophila pneumoniae infected rate,Cpn specific genes were detected by PCR in PBMC and RBC, and C.pneumoniae-specific IgG antibodies was detected by ELISA in sera samples from respiratory tract infection patients. Combined with the medical history and clinical features, the role of C. pneumoniae infection played in respiratory tract disease was analyzed which will benefit for the study of how to control C. pneumoniae infection.Methods:Blood samples were collected from 173 respiratory tract infection patients and 52 healthy volunteers. DNA was extracted from PBMC and RBC and sera were isolated from the blood samples. The 16S rRNA and MOMP gene of C. pneumoniae were detected by PCR from the DNA samples and C. pneumoniae specific IgG were measured by ELISA kit from the sera samples. PCR products were detected by 1.5% agarose gel electrophoresis and were sequenced by Sangon Company. Combined with the clinic data, the difference of C. pneumoniae infected rate in different age group and different disease group was analysed.Results:The results of PBMC extrct as follow: 173 people of the respiratory tract infection group, the PCR(16S rRNA)positive rate is 33.52%(58/173); the PCR(MOMP) positive rate is 32.40%(56/173). 52 people of the healthy group, the positive amount of PCR(16S rRNA) is 5 and positive rate is 9.62%; the positive amount of PCR(MOMP) is 5 and positive rate is 9.62%. There is no target fragment in extract of RBC;and MOMP PCR products with Cpn AR-39 of the MOMP gene 99% consistent; 16S rRNA PCR products of 16S rRNA genes with the AR-39 consistent 97%.The results of serum by ELISA(Cpn-IgG) as follow: 173 people of the respiratory tract infection group, the positive amount is 88 and positive rate is 50.87%; 52 people of the healthy control group , the positive amount is 16 and positive rate is 30.77%. In the group of 18～40 age, the positive amount is 14/35(40.00%, Cpn-IgG) , 8/35(22.86%, 16S rRNA) and 6/35(17.14%, MOMP). In the group of 41～60 age, the positive amount is 10/36(27.78%, Cpn-IgG) , 5/36(13.89%, 16S rRNA) and 5/36(13.89%, MOMP). In the group of 61～79 age, the positive amount is 50/83(60.24%, Cpn-IgG) , 40/83(48.19%, 16S rRNA) and 40/83(48.19%, MOMP). In the group of above 80 age, the positive amount is 14/19(73.68%, Cpn-IgG) , 5/19(26.32%, 16S rRNA) and 5/19(26.32%, MOMP). According to the positive rate of each group, it can be seen that Cpn infected rate of aged group is the highest. A cpn-IgG result of three PCR-postive patients with respiratory tract infection is negative. Likewise, among 35 Cpn-IgG positive patients, 35 patients are 16S rRNA PCR negative and 33 patients are MOMP PCR negative. High consistence of two Cpn specific gene in PCR shows the similarity of amplifying 16S rRNA and MOMP when detecting Cpn infection by PCR.Among the Common Clinical respiratory tract diseases,COPD patients have the highest positive rate of Cpn infection. It suggests that Cpn infection is an important reason for the occurrence and development of COPD.Conclusion:1. Chlamydophila pneumoniae is one of the most important respiratory tract pathogen proved to be the main pathogen for C. pneumoniae.2. Old people are of high-risk group for Cpn infection and there is high relationship between COPD and Cpn infection.3. Cpn parasitizes in the PBMC not RBC. So the blood infection risk of Cpn can be reduced greatly by clinic blood component transfusion.4. Cpn infection has no specific clinical symptoms and always infects with other bacteria.