Evaluation of Prevalence of S. pneumoniae pharyngeal carriers under 5 years of age by lytA gene detection

Background and Objective: Streptococcus pneumoniae is one of the leading causes of death among children worldwide. Nasopharyngeal colonization in children can spread pneumococcal infections in the community. This study aimed to evaluate the prevalence of S. pneumoniae strains isolated from healthy pharyngeal carriers less than 5 years of age. Methods: This cross-sectional descriptive study was performed on 150 children under 5 years old in the city of Shiraz. After nasopharyngeal swab sampling, the samples were cultured on blood agar containing 5% sheep blood. The cultures were incubated at 37 °C for 24 h. Primary identification was carried out using optochin sensitivity testing, bile solubility testing and gram staining. Molecular identification of S. pneumoniae strains was done using lytA gene-specific primers. Results: Of the 150 samples collected from healthy children, 24.67% were pharyngeal carriers of S. pneumoniae. The highest frequency of pneumococcal strains was related to male carriers (n= 22, 59.46%) and the children aged 1-2 years (n=11, 29.73%). The results showed no significant association between the prevalence of pharyngeal carriage and gender or age. Conclusion: Given the increasing rate of pharyngeal carriage of S. pneumoniae in children as a risk factor for respiratory tract infections, there is a need for further monitoring of the circulating serotypes and investigation of antibiotic-resistance mechanisms.