Abstract:
The incidence of Staphylococcus aureus-related skin and soft tissue infections and invasive disease such as bacteraemia, is rising in New Zealand. S. aureus bacteraemia is more prevalent, and causes more deaths in New Zealand than meningococcal disease. This has placed a significant burden on both the healthcare system and in communities, with Maori and Pacific children at increased risk for disease. A better understanding of determinant risk factors and effective preventative treatment for S. aureus carriers is required to decrease this risk. Nasal swabs collected weekly from adults with infrequent healthcare contact [healthy group] and people requiring haemodialysis [renal group] were cultured to classify participants as either persistent, intermittent or non-carriers of S. aureus. The spa types of S. aureus isolates from persistent and intermittent carriers were identified and tested for susceptibility to antimicrobials and chlorhexidine. Microbial flora swabs were collected from a subset of persistent, intermittent and non-carriers. Cultivated isolates from these swabs were identified using MALDI-TOF mass spectroscopy and 16S rDNA PCR amplification. Healthy and renal group participants did not exhibit differences in patterns of S. aureus carriage. Susceptibility testing revealed S. aureus isolates with reduced susceptibility to chlorhexidine in healthy group participants only. The diversity of spa types in the population did not differ between groups; however, subsets of distinct, group specific spa types were identified. Examination of the nasal microbial flora of study participants demonstrated a significant role for S. aureus and S. epidermidis in the composition of nasal microbial flora in association with nasal carriage. S. epidermidis was strongly associated with the nasal flora composition of non-carriers.
