Semi-quantitative Sputum Procalcitonin Test For The Clinical Application Of Pulmonary Infectious Diseases

Objective: We detected sputum procalcitonin(PCT) in patients with pulmonary infectious diseases using the method of semi-quantitative test, and compared with traditional inflammatory markers. The aim is to clarify the assistant value of diagnosis in pulmonary infectious disease, particularly bacterial infections.Materials and methods: 150 patients diagnosed with pulmonary infectious disease were chosen in the respiratory department of The First Hospital of Jilin University from Jul 2015 to Jan 2016. All patients were diagnosed with the following standards: According to the diagnostic criteria established by the American College of Chest Physicians and Critical Care Medicine Consensus Conference, it is regarded as infection when conforming to the following two points in five At least.(1) heating temperature>38°;(2) peripheral blood leukocyte count> 12×109/L; Immature neutrophils(nuclear) rods>10%;(3)Chest X-ray revealed lung infection;(4) has purulent secretion in the body;(5) clinical antibiotics has already decided to start or maintain. All patients with the following diseases were excluded:(1)patient with other infections except the respiratory system;(2)patients with pulmonary infection or other infections in one months;(3)patients with tumor and immune deficiency.(4)patients with immune system disease and kidney disease.(5)patients with heart and cerebrovascular accident or major operation or severity trauma etc nearly six months. We tested sputum PCT levels of all selected patients, and collect sputum culture. At the same time, we also tested routine blood, c-reactive protein, serum PCT, ESR, etc for every patient, and then recorded the hospitalization days. We compared sputum PCT and other traditional inflammatory markers according to the disease types and sputum culture respectively, and analyzed the correlation between sputum PCT and hospitalization days, sputum culture positive rate.Results:(1) Sputum PCT has higher positive rate in various pulmonary infectious disease, including sputum positive predictive value of PCT is highest in patients with lung abscess, followed by bronchiectasis combined infection and AECOPD combined infection, respectively 85.7% and 80.6%.(2) The correlation between sputum PCT and hospitalization days, sputum culture positive rate:sputum PCT has significant positive correlation with the hospitalization days and sputum culture positive rates(rs=0.563, 0.289, P<0.05), the higher the concentration of sputum PCT is, the longer hospitalization days is, and the higher sputum culture positive rate is. Comparing other inflammatory markers, NE、CRP、ESR、serum PCT are associated with hospitalization days(rs=0.339, 0.328, 0.293,0.389, P<0.05); and WBC、NE、CRP are associated with sputum culture positive rates(rs=0.209, 0.211, 0.225, P<0.05), but spearman’s rho is lower than sputum PCT. While WBC has no obvious correlation with the hospitalization days, and serum PCT、ESR not to sputum culture positive rates(P>0.05).(3) According to the result of sputum culture, all patients are divided into sputum culture positive group and negative group. Compared with negative group, sputum PCT、WBC, NE, CRP are higher in positive group, and has significant statistical difference(P<0.05). But the serum PCT, ESR has no obvious statistical significance(P>0.05). sputum culture positive group is also classified that bacteria group, fungi group and mixed-infection group. We conclud that: sputum PCT is increased significantly in bacteria group and mixed-infection compared with fungi group, and has significant statistical difference(P<0.05), and there is not difference between bacteria group and mixed-infection. Whereas the serum PCT, WBC, CRP, ESR has no obvious statistical significance(P>0.05). In fungi group, sputum PCT show the slightly higher.(4) Sputum culture bacterial positive is regarded as the gold standard for bacterial infections, we draw sputum PCT and other inflammatory indicators of ROC curve, the resulting: The under curve area of sputum PCT is significantly greater than other inflammatory indexes, and sputum PCT has better sensitivity and specificity than other inflammatory indexes. When sputum PCT is0.5ng/ml, the sensitivity and specificity are the highest for lung bacterial infections. The sensitivity is 58.1%, and the specificity is 88.5%.Conclusion:(1) Sputum PCT will be helpful for the diagnosis of pulmonary infection, it can be used as a auxiliary marker.(2) Sputum PCT has positive correlation with the length of hospitalization days and sputum culture positive rate, it may be as a index to predict the severity of infections.(3) When pulmonary bacterial infections happen, sputum PCT will be significantly increased, When sputum PCT is 0.5ng/ml, the sensitivity and specificity are the highest for lung bacterial infections. The sensitivity is 58.1%, and the specificity is 88.5%.(4) Sputum PCT can mildly increase in pulmonary fungal infections.