The Possibility of Differentiating Between Pneumococcal Pneumonia and Colonized <i>S. pneumoniae</i> in Children by Cycle Threshold of Real-time PCR

Abstract

Background: Community-acquired pneumonia (CAP) is a frequent childhood disease. There are several methods to identify the bacterial etiology of CAP, but many of them cannot be performed due to limitations. Streptococcus pneumoniae often causes bacterial pneumonia, and upper respiratory tract (URT) colonization is needed for lower tract infection. Finding a cut-off to define if this bacterium causes pneumonia or just colonization can be helpful for the physician. Objectives: The present study aimed to determine a cycle threshold (CT) cut-off for patients with pneumococcal pneumonia and healthy children. Methods: Two groups were designed in this study: (1) Suspected patients with pneumococcal pneumonia and (2) healthy children. The identification of S. pneumoniae was conducted using real-time PCR (RT-PCR), and the CT values were compared in these two groups. Results: The total colonization rate of S. pneumoniae in children below 5 years was 56%. These rates in patients and healthy children were 59% and 53%, respectively. The mean of the CT is 24.85 in the patient group and 24.40 in the control group. There is no significant difference in CT values between patients and healthy children (P > 0.05). Conclusions: The results of this study showed that we were unable to find a precise cut-off for the CT value in patients with pneumococcal pneumonia compared to healthy children, which would effectively differentiate between the two groups because of the high colonization of this bacteria in children.