Isolation and Characterization of Gram-Positive Bacteria from Saliva of Children with Down Syndrome and Healthy Children in Benghazi, Libya

Abstract

Background: Individuals with Down syndrome (DS) present unique anatomical and physiological oral characteristics that profoundly shape the salivary microbial ecosystem. This comparative cross-sectional study was conducted to isolate, characterize, and evaluate cultivable Gram-positive bacterial species in saliva samples collected from children with Down syndrome and healthy control children in Benghazi, Libya. Methods: A total of 100 children aged 5-14 years were recruited, including 46 children with Down syndrome and 54 healthy controls. Unstimulated whole saliva samples were collected under aseptic conditions and evaluated using standard microbiological culture techniques. Bacterial identification was performed based on colony morphology, Gram staining, biochemical characterization, and automated identification using the RENDER MA120 System. Data were analyzed using SPSS, with statistical significance set at P < 0.05.
Results: The recovered oral flora strictly comprised Gram-positive bacterial species, predominantly Streptococcus pyogenes, Streptococcus pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecalis. Among all isolates, S. pyogenes and S. aureus were the most frequently recovered species, each accounting for 30.0% (n = 12), followed by S. pneumoniae at 20.0% (n = 8), S. epidermidis at 12.5% (n = 5), and E. faecalis at 7.5% (n = 3). Conclusion: The findings establish important baseline microbiological profiles regarding Gram-positive salivary colonization among Libyan pediatric populations with Down syndrome, contributing to improved preventive oral healthcare strategies.