Staphylococcus aureus carriage and infections

Who carries S. aureus?
Twenty to forty percent of people carry S. aureus in their anterior nares at any time (Wheat, Kohler & White, 1981). In 1991, Reagan et al  cite prevalence studies of healthy persons with S. aureus carriage rates ranging from 25% to 65%.

Williams (1963) reported that up to 10% of study subjects carried two strains of S. aureus (discriminated via phage typing). Reagan et al reported that 12% of their population of healthy healthcare workers carrying S. aureus carried more than one strain (discriminated with restriction digest).

The role of nasal carriage in infection
From Casewell and Hill (RCT, nealth care workers, 1986):

"Whilst contributing to the reservoir of S. aureus,  the role of nasal carriage in ...infection is uncertain. The anterior nares may provide a source of organisms for the colonisation of a subject's perineum or abnormal skin, or for the auto-infection of patients with, for example, burns, leukemia or recurrent boils."

From Boelaert et al (RCT, haemodialysis patients, 1991):

"[S. aureus] is the most frequently isolated pathogen, usually causing infection at the vascular access site, often associated with bacteremia. Nasal carriage of S. aureus is considered to play an important role in the pathogenesis of these infections [3]. Eradication of nasal S. aureus  by oral rifampicin has been reported to be effective in haemodialysis patients [2]."

From Reagan et al (RCT, healthy healthcare workers, 1991):

"Clearance of S. aureus from the hands appears to be an important finding of our study, perhaps explaining the observed decrease in infections with S. aureus in patients on hemodialysis who received rifampicin after elimination of nasal carriage...a major benefit of the eradication of nasal carriage may be the prevention of S. aureus infection in high-risk groups."