Background: Staphylococcus aureus (SA) is a human commensal and a common cause of both sporadic and epidemic infections. Nasal SA carriage is an important risk factor for various infections.
Molecular characterization was applied to study the dynamics of S. aureus carriage among recruits, during the early period of military training.
Methods: Nasal swabs were obtained at the beginning of training and 2-4 weeks later from 674 soldiers undergoing basic training in three infantry training facilities during 2011-12. Genetic profiles based on spa typing, presence of a virulence factor gene (PVL) and antibiotic resistance profiles were determined for the 475 SA isolates collected.
Results: The majority (92.2%) of carriers at baseline remained carriers 2-4 weeks later, of whom 84.9% carried the exact same spa type. 25.4% of initial non-carriers acquired SA by the end of follow up. Overall, 121 different spa types were found, t6605 was the most prevalent (8.18%). Spa types varied between the bases, including the most prevalent types at each base. 54% of acquired types were previously isolated in the base.
High resistance rates were observed to penicillin (74%), clindamycin (33%) and erythromycin (35%). A single methicillin-resistant SA (MRSA) isolate was found PVL was positive in 1 out of 294 (0.3%) strains tested.
Conclusions: Colonizing MSSA strains in young adults in Israel were highly diverse as detected by spa typing, whereas MRSA colonization prevalence was very low. Molecular characterization will reflect the dynamics of strain transmission between the recruits.
