Nasal colonization of Staphylococcus Aureus and Streptococcus Pneumoniae in preschool children attending selected immunization clinics, Kandy, Sri Lanka

Abstract

Staphylococcus aureus colonization is quite common in children in Sri Lanka. Pneumococcal carriage is a prerequisite for pneumococcal disease. The objective of this study was to examine the prevalence and risk factors of nasal carriage of S. aureus and Streptococcus pneumoniae in preschool children. Both anterior nasal swabs and nasopharyngeal swabs (NPS) were collected from 375 children between 2 to 5 years, attending immunization clinics at Teaching Hospital Peradeniya and Yatinuwara MOH area during June 2023-January 2024. Nasal swabs were enriched in 6.5% NaCl and NPS were stored at -80 oC. S. aureus and S. pneumoniae were isolated using conventional microbiological testing. The study group had a median age of 54 months (IQR: 36-60), with 188 (50.1%) males and 187 (49.9%) females. Among 375 participants, 101 (26.9%) were colonized with S. aureus, 73 (19.5%) with S.pneumoniae and 21 (5.6%) with both. Of these, 52 (13.9%) carried only S.pneumoniae and 80 (21.3%) carried only S.aureus. Kindergarten attendance (OR=1.92, 95% CI=1.13-3.27), smokers at home (OR=1.85, 95% CI=1.04-3.30), having recent upper respiratory tract infections – (URTI) (OR=16.39, 95% CI=2.23-120.47), family members with URTI (OR=1.83, 95% CI=1.09-3.08) were significantly associated with pneumococcal colonization. No significant associations were found with S.aureus colonization. The median age was significantly different between co-colonized (60 months, IQR: 52.5-60) and non-co-colonized children (48 months, IQR: 36-60) (p=0.017). The median weight differed significantly between co-colonized (15.000kg, IQR: 12.450-16.475) and non-co-colonized children (13.200kg, IQR: 11.690-15.100) (p=0.021). Kindergarten attendance (OR=4.016, 95% CI=1.33-12.18) was significantly associated with co-colonization. No significant association found between S.aureus and pneumococci colonization (p=0.694). As a conclusion, S.aureus and S.pneumoniae colonization rates are considerably higher among children aged between 2 to 5 years. Kindergarten attendance is a significantly associated factor for S.aureus and S.pneumoniae co-colonization.