Vaginal Carriage of S. aureus and ORSA Among Sexually Active Adolescent Women

Background:
Staphylococcus aureus is a virulent organism that colonizes the nares, axilla, vagina, and damaged skin surfaces. The rate of oxacillin resistant S. aureus (ORSA) infections has increased in the past 20 years. Among persons age 1-19 years, 36% have nasal colonization with S. Aureus and 0.6% have ORSA. ORSA has been isolated from genital skin infections and heterosexual transmission has been suspected.

Objective:
To determine the prevalence of vaginal S. aureus and ORSA among adolescent women.

Method:
Vaginal swabs were obtained from adolescents attending a teen health clinic during a 3 month time period for this cross-sectional study. Basic demographic information included age, race, and sexual activity. After routine wet mount procedures, the residual sample (swab and remaining saline) was transferred to the laboratory, where specimens were plated onto Mannitol Salt Agar and incubated at 35° C in air. Colonies that fermented mannitol were confirmed as S. aureus using latex agglutination and identified as ORSA using the Vitek 2 system. Point estimates and 95% confidence intervals (CI) were calculated.

Result:
Preliminary results for 201 specimens obtained from sexually active women are presented. The mean age was 18.1 years (range 13.5 - 21.9); 81% were black, 18% white and 1% other race. S. aureus was present in 12 samples for a point estimate of 6.0% (CI: 3.1% -10.1 %). ORSA was detected in one sample, giving a vaginal prevalence estimate of 0.5% (CI: 0.01% - 2.7%) No differences were detected in the prevalence of S. aureus by age or race, although thus far no cases of S. aureus were observed in those under age 16. Data collection is ongoing.

Conclusion:
The prevalence S. Aureus in the vagina of adolescent women is low, and ORSA is rare.

Implications:
Vaginal secretions are an unlikely reservoir for ORSA infections.