Geographic distribution and prevalence of potential asymptomatic Staphylococcus spp. in the nasopharyngeal cavity of elementary school boys at Al-Madinah, KSA.

Nasal swaps were collected from 405 elementary school boys of eight governmental schools located within several districts in Al-Madinah city to be screened for asymptomatic carriage of potential Staphylococcus pathogens. A total of 138 Gram-positive staphylococci isolates (34%) showing blood hemolysis were selected. Based on their morphological, cultural characteristics and Restriction enzyme analysis Isolates were grouped into 12 phenotypic within four distinct clusters. The 16S rDNA sequence analysis of all isolates revealed S. aureus to be the most prevalent (80%), followed by S. epidermidis (9%) and finally S. hominis and S. simulans accounting for 6% and 5% respectively. Staphylococcus isolates were detected with higher frequency in participants of age group 7–9 years, with the lowest numbers of staphylococci (18%) isolated from the schools located in the western area. Multiplex PCR assay revealed that all S. aureus isolates (20%) which were phenotypically recognized as MRSA by the Kirby–Bauer disc diffusion method contained the mecA gene. MecA gene was also detected in three coagulase-negative staphylococci isolates. [ABSTRACT FROM AUTHOR]