Background: Female sex hormones have been related to the risk for persistent nasal carriage of staphylococcus aureus (SA) in healthy individuals. However, whether NCSA rates vary by menstrual cycle phase remains unclear.
Methods: We followed healthy female carriers of SA and repeatedly sampled anterior nares every 3-4 days since menstruation for six menstrual cycles. Ovulation in each cycle was confirmed by urinary test; the periovulatory window included 3-4 days prior to ovulation. The presence of staphylococcus aureus (SA) was based on culture results. We used random-intercept Poisson regression models to determine whether SA or MRSA carriage rates were phase-dependent within the same woman. We reported incidence rate ratios (IRR) and estimated the 95% confidence intervals (CI) using robust estimation methods to account for within-person correlation for repeated measures.
Results: Among 15 carriers (baseline methicillin-resistant SA [MRSA]: 53%), we collected 762 nasal swabs over a median number of 50 visits per subject (interquartile range [IQR]: 47-52), with a period prevalence of 65.0% for SA and 36.7% for MRSA.
NCSA was detected in 66.9% of swabs collected in the luteal phase as compared to 61.3% and 65.5% of those in the follicular and periovulatory phase, respectively. After adjusting for age, baseline MRSA status and use of antiseptic agents for nostril cleansing at follow-up, the NCSA rate in the luteal phase was not significantly different from that in the follicular phase (adjusted IRR: .99, P: .921) for a given woman. The average frequency of using antiseptic agents was associated with a 2.5-fold increased risk for NCSA (adjusted IRR: 3.57, P: .013) while the use of antiseptic cleanser prior to each visit was correlated with a reduced risk for NCSA (adjusted IRR: 0.54, P: .05)
The carriage rate for MRSA was 7.1% higher in the luteal (39.5%) than that in the follicular phase (32.4%), yet, there were no statistical differences in the multivariable model (adjusted IRR: 0.99, P: 0.901; Table 1).
Conclusion: In a female cohort of healthy carriers with NCSA, menstrual cycle phases were not associated with colonization rates of SA or MRSA. While antiseptic use for nose cleaning was related to NCSA, we did not identify host factors associated with MRSA colonization.
S. H. Liu,
K. F. Chen, None
H. R. Lu, None
Y. C. Huang, None