Rapid and direct molecular detection of Streptococcus pneumoniae and Haemophilus influenzae isolated in oropharynx and nasal cavity of children.

ABSTRACT

There is a direct correlation between asymptomatic oropharyngeal colonization by pathogenic bacteria and the prevalence of paediatric respiratory infections. Streptococcus pneumoniae and Haemophilus influenzae are common cause of serious bacterial infections such as meningitis in children. This study aimed to monitor healthy children to detect asymptomatic carriers of S. pneumoniae and H. influenzae. In the present cross-sectional study, real-time PCR assay was developed and evaluated in comparison with culture for direct detection of S. pneumoniae and H. influenzae in 123 oropharynx and nasal cavity specimens from healthy children in Ilam, Iran. In addition, virulence factor (ply and hpd) and iron uptake (tbpA and piuA) genes were evaluated by PCR. Our results demonstrated that among all isolates only 14 S. pneumoniae and eight H. influenzae were identified by phenotypic methods, whereas 37 and 21 S. pneumoniae and H. influenzae were identified, respectively, by real-time PCR assay. All S. pneumoniae and H. influenzae isolates possessed tbpA and piuA genes. Also, 81% (30/37) of S. pneumoniae isolates were positive for ply gene, which encoded pneumolysin, as well as 90% (19/21) of H. influenzae isolates were positive for hpd gene. Simultaneous colonization of S. pneumoniae and H. influenzae could indicate the importance of monitoring of healthy children to identification of carriers.