In Vitro Study to Assess Effective Cleaning Techniques for Removing Staphylococcus aureus from Menstrual Cups

Background: We sought to determine the effectiveness of common cleaning procedures in eliminating S. aureus from silicone menstrual cups. Methods: In this in vitro study, we tested four cleaning techniques: (1) cold water; (2) cold water and liquid soap; (3) cold water followed by steeping the cup in boiled water for 5 min in a ceramic mug covered with a small plate; and (4) cold water and soap followed by steeping the cup in boiled water as in (3). Human blood was coated to the inner and outer surface of each cup, dried, and incubated with 10 6 S. aureus colony-forming units (CFU/mL). All tests were performed in triplicate. Viable bacterial abundance was measured with decadic dilution and drop plate or surface plating. Results: Bacteria were most effectively eliminated by cleaning cups with soap and water and then steeping in boiled water (0 CFU/cup vs. 2.075 × 10 8 /cup no cleaning, p = 0.005). This was not statistically significantly different from washing cups with water only and steeping 5 min in boiled water (14 CFU/cup). Raised lettering on the outer surface of the menstrual cups resulted in more bacterial recovery from pieces with lettering than without lettering. Conclusions: These results advance knowledge of between-period menstrual cup cleaning recommendations, suggesting that the logistical challenges of continuous boiling may be eliminated with steeping at least 5 min.