Prevalence and Antimicrobial Susceptibility of Staphylococcus aureus Isolated from Anterior Nares of Pre-School Children in Phatthalung Province

Abstract

Ninety nasal swabs of healthy pre-school children from 3 kindergarten schools in Phatthalung province were determined for the prevalence of Staphylococcus aureus.  Swabs were inoculated onto Mannitol Salt Egg Yolk Agar and incubated at 37 oC for 24 h.  S. aureus isolates were identified by standard microbiological methods.  Of the 90 nares samples screened, 47 samples (52.22 %) showed the growth of S. aureus.  In 47 S. aureus isolates from nares samples, 44 were methicillin-susceptible S. aureus (MSSA) and 3 were methicillin-resistant S. aureus (MRSA) which were mecA and nuc positive.  The oxacillin MIC of these MRSA isolates were 16 µg/ml, 32 µg/ml and 256 µg/ml, respectively. Disk diffusion susceptibility test showed that 3 MRSA isolates were resistant to penicillin, oxacillin, cephoxitin, erythromycin and tetracycline.  For SCCmec typing, 2 isolates (R24 and S13) were Type III and 1 isolate (R9) was Type II/III. Interestingly, 1 MRSA isolate was positive for pvl gene.  The results suggested that MRSA is present in the Thai community and MRSA prevalence should be further explored and observed.