Diagnostic value of procalcitonin C-reactive protein and pathogens detection in lower respiratory tract infections

Objective To investigate the diagnostic value of measurement of serum PCT,CRP and the pathogens antibody of respiratory tract infection and culture of bacteria.Methods 119 patients with lower respiratory tract infection were divided into two group,75 patients with bacterial infection and 44 patients with non-bacteria infection,and 60 healthy people were included.All serum samples were measured of PCT(by Brahms PCT-Q),CRP(by using immunity-turbidity method)and the antibody of pathogens for respiratory tract infection.All patients were cultured for bacteria in phlegm and blood.Results The levels of PCT and CRP in bacterial infection group were higher than those in non-bacteria infection group and healthy controls(P0.01).The PCT 0.5 ng/mL,CRP 8.0 mg/L as the threshold,the sensitivity of PCT and CRP were 89.3 % and 84.0 %,with significant difference(P 0.05),and compared with non-bacterial pathogens group and the healthy control one,the difference was statistically significant(P0.01).The specificity of PCT for the diagnosis of bacterial infection was 88.4 %,which was higher than that of CRP(78.8 %),with significant difference(P0.05);Joint detection of sputum culture and blood culture on bacteria increased the positive rate(41.3%);The sensitivity of diagnostic tests for lower respiratory tract infections by PCT and CRP was higher than bacterial culture.The positive detection rate of respiratory tract infection pathogens antibody for non-bacterial pathogen infection was 56.8 %.Conclusion PCT and CRP are suitable for the early diagnosis of bacterial infection,and sensitivity of PCT is higher than that of CRP.Combined detection with pathogens antibody of respiratory tract infection and bacterial culture on diagnosis and differential diagnosis of lower respiratory tract infection has important value.