[Prevalence of Staphylococcus aureus nasal colonization in injection drug users].

A prevalence study was conducted to evaluate Staphylococcus aureus nasal colonization in two groups of injection drug users recruited at two drug addiction treatment centres in Rome and Frosinone (Italy). Prevalence of Staphylococcus aureus nasal colonization in the 181 subjects included in the study was 8.83%. Significantly increased carriage rates were found among drug users in Frosinone with respect to those in Rome. No other significant determinants of colonization were identified through multiple logistic regression analysis. Only 2 of 16 Staphylococcus aureus strains (12.5%) were found to be methicillin resistant. Genomic DNA restriction pattern analysis, through SmaI digestion and pulsed field gel electrophoresis, demonstrated wide genetic heterogeneity among the isolates. Although the great majority of PFGE patterns were found in single isolates, in some cases common patterns were identified in isolates obtained from different drug users, clearly indicating the possibility of interhuman transmission of Staphylococcus aureus in this population.