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

There is a direct correlation between asymptomatic oropharyngeal colonization by pathogenic bacteria and the prevalence of paediatricrespiratory infections. Streptococcus pneumoniae and Haemophilus influenzae are common cause of serious bacterial infections such asmeningitis 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 ofS. pneumoniae and H. influenzae in ۱۲۳ oropharynx and nasal cavity specimens from healthy children in Ilam, Iran. In addition, virulencefactor (ply and hpd) and iron uptake (tbpA and piuA) genes were evaluated by PCR. Our results demonstrated that among all isolates only۱۴ S. pneumoniae and eight H. influenzae were identified by phenotypic methods, whereas ۳۷ and ۲۱ S. pneumoniae and H. influenzaewere identified, respectively, by real-time PCR assay. All S. pneumoniae and H. influenzae isolates possessed tbpA and piuA genes. Also,۸۱% (۳۰/۳۷) of S. pneumoniae isolates were positive for ply gene, which encoded pneumolysin, as well as ۹۰% (۱۹/۲۱) of H. influenzaeisolates were positive for hpd gene. Simultaneous colonization of S. pneumoniae and H. influenzae could indicate the importance ofmonitoring of healthy children to identification of carriers.

Keywords:

Detection , Haemophilus influenzae , iron uptake , real-time PCR assay , Streptococcus pneumoniae , virulence factors