['To explore the correlations between Chlamydia pneumoniae (CP) infection and IgA nephropathy (IgAN).', 'Seventy patients with primary IgAN were enrolled in the study. Seventy serum specimens from healthy blood donors and twelve renal autopsy specimens from accidental death bodies were regarded as control groups. Serum CP IgG and CP IgA antibody titers were detected by indirect immunofluorescence. CP DNA of renal tissue was measured by fluorescent quantitative PCR. Finally, using statistical methods, we analyzed the correlations of CP infection and CP DNA of renal tissue with clinical manifestations and kidney pathological changes of IgAN patients.', 'The rate of CP persistent infection in IgAN group was higher than that of healthy blood donor group (P<0.01). The rate was not significantly different within the IgAN group, such as among acute infection, previous infection and no infection subgroups (P>0.05). It was higher in the patients with gross proteinuria and/or durative renal insufficiency than in non-gross proteinuria patients (P<0.05). The scores of glomerular patholopical and tubulointerstitial injury of CP persistent infection patients were higher than those of non-persistent infection ones (P<0.05). The renal injury of CP persistent infection patients was more severe than that of non-persistent infection ones. The positive rate of CP DNA in gross proteinuria and/or renal insufficiency patients was higher than that of non-gross proteinuria patients (P<0.05). The scores of glomerular pathological and tubulointerstitial injury of positive CP DNA patients were respectively higher than those of negative CP DNA ones (P<0.05, P<0.01). The renal injury of patients with positive CP DNA was more severe than that of negative CP DNA ones. CP persistent infection was obviously correlated with renal CP DNA (P<0.01).'] Is [ Chlamydia pneumoniae persistent infection associated with primary IgA nephropathy ]?