The aim of this study was to test the detection performance of the cpsA, lytA and ply genes through qPCR in the identification of Streptococcus pneumoniae in respiratory tract samples. Specificity was tested on a panel of 128 streptococci and other bacteria DNA samples. The qPCR assay was tested on a total of 51 respiratory tract samples from patients with community-acquired pneumonia (CAP). The specificity of the cpsA, lytA and ply genes was 100%, 100%, and 86%, respectively. The quantitative assessment, based on lytA, determined a cutoff value of ~2x104, 4x102 and 4x102 DNA copies per 1 mL of valid sputum, tracheal aspirate and bronchial aspirate samples, respectively. The results from the present study suggest that qPCR detection of all three genes would be optimal in the accurate detection of Streptococcus pneumoniae.
Keywords: Streptococcus pneumoniae; community-acquired pneumonia; qPCR; quantification; specificity.