Nasal Carrying by Staphylococcus Aureus ST398 Strains in Community and Hospital Settings

Staphylococcus aureus (SA) is a ubiquitous bacterium, part of the human commensal flora. The mucosa of the anterior nasal cavities represents the preferred site of colonization of SA. The SA ST398 clone, belonging to CC 398, was initially described as a zoonotic agent initially identified in France and the Netherlands. In fact, ST398 strains are separated into two distinct populations: a methicillin-resistant SA population (SAMR) with notion of contact with animals and a more virulent methicillin-sensitive SA population (SAMS) than its counterpart, isolated from serious human infections and without notion of exposure to farm animals. Recently, we have shown that, in SA bacteremia, all strains of SA ST398 are sensitive to methicillin and that the prevalence of ST398 among all SAMS responsible for bacteremia at Besançon University Hospital increased between 2009 and 2014, increased from 4 to 15%. However, we were unable to study nasal colonization to support the mode of acquisition of SA ST398 (community vs. healthcare acquisition).