Nasal Carriage of Staphylococcus aureus in Healthy Adults and in School Children

Staphylococcus aureus (S. aureus) is a microorganism that colonizes the skin and mucosal surfaces of healthy individuals, but it is also one of the most common causes of community-acquired and hospital infections. Nasal carriage of S. aureus represents a major risk factor for the development of infection with this bacterium. A special therapeutic problem are methicillin-resistant isolates of S. aureus (MRSA). The aim of this study was to assess the nasal carriage of S. aureus in healthy individuals in the local community, and the sensitivity of the microorganism to antibiotics. The study enrolled 56.868 healthy individuals aged 19 to 65 years, and 2.040 healthy school children aged 15 to 19 years. Specimens to be studied were obtained from anterior nares. We used the disk diffusion method (Kirby-Bauer) on Mueller-Hinton agar to assess the sensitivity of isolated S. aureus. S. aureus was isolated in 1.381 (2.34%) respondents. Positive findings were obtained in 2.33% of adult examinees, and in 2.59% of studied school children. We found a low level of susceptibility only to penicillin (5.36%). The susceptibility of S. aureus isolates to all other tested antibiotics was present in a high percentage, with the lowest percentage of susceptibility to doxycycline (71.54%) and erythromycin (86.09%). The highest percentage of susceptibility of tested isolates was reported for fusidic acid (99.27%). In relation to the total number of S. aureus isolates from nasal swabs in adults, MRSA was present in 8.96% (119 isolates), while there were 4 MRSA isolates from nasal swabs in school children. In this study, we established a low percentage of nasal carriage of S. aureus in the population of healthy individuals, but a high percentage of MRSA.