Diagnostic value of procalcitonin and C-reactive protein for gram-negative bacteria-caused lower respiratory tract infection in elderly patients

Objective To evaluate the diagnostic value of procalcitonin( PCT) and C-reactive protein( CRP) for lower respiratory tract infections caused by Gram-negative pathogenic bacteria in elderly patients. Methods Retrospective analysis was performed. 87 elderly patients with diagnosed lower respiratory tract infections were divided into three groups according to the type of infection,and compared with healthy volunteers. The PCT and CRP levels in different type of infections were compared; the diagnostic values of PCT and CRP were analyzed by using ROC curves. Results The PCT and CRP levels in both Bacterial infection and non-bacterial infection groups were statistically different from those in control group( P 0. 05). The PCT levels in Gram-negative bacterial infection was significantly higher than that in Gram-positive bacterial infection( P 0. 01). Areas under the curve of PCT and CRP were 0. 966 and 0. 928 respectively according to the ROC curves of gram-negative group and the control group.Conclusion The PCT and CRP have a definite significance for differential diagnosis of elderly lower respiratory tract infection caused by Gram-negative bacteria,and the diagnostic value of PCT is higher than that of CRP.