The aim of this study is to investigate the utility of several
biomarkers in differentiating bacterial community-acquired lower
respiratory tract infection (CA-LRTI) from non-bacterial CA-LRTI in children and the difference of their diagnostic performance between
pneumonia and
bronchitis. A retrospective cohort study composed of 108 pediatric patients hospitalized for CA-LRTI was performed during 2010-2013. Based on the findings of chest X-ray and sputum samples, patients were divided into 4 categories, group of
bacterial pneumonia or
bronchitis, and non-bacterial (viral or etiology-unknown)
pneumonia or
bronchitis. Peripheral white blood cell and neutrophil counts, and serum
C-reactive protein (CRP) and
procalcitonin (PCT) levels were compared among the 4 groups. Finally, 54 patients were the subject of this study. In the patients with
pneumonia, serum CRP and PCT levels were significantly elevated in the group of
bacterial pneumonia (CRP: p = 0.02, PCT: p = 0.0008). The area under the receiver operating characteristic curve for PCT for distinguishing between bacterial and non-
bacterial pneumonia was the largest, and sensitivity, specificity, positive predictive value and negative predictive value of PCT were best among 4 markers. On the other hand, in the patients with
bronchitis, neutrophil count was significantly decreased in non-bacterial
bronchitis whereas no significant differences of WBC count, CRP level or PCT level were seen. In conclusion, PCT was the most useful marker to differentiate
bacterial pneumonia whereas neutrophil count contributed most to the discrimination of bacterial
bronchitis. The diagnostic performance of
biomarkers may be different between
pneumonia and
bronchitis.