Survival of methicillin-resistant Staphylococcus aureus on toothbrushes stored under protective covers and sanitizers

Abstract

OBJECTIVES: To investigate the survival of methicillin-resistant Staphylococcus aureus on toothbrushes stored under commercially available antimicrobial and non-antimicrobial covers. METHODS: Standardized inocula of methicillin-resistant Staphylococcus aureus (MRSA) ATCC 700698 were prepared and adjusted to a 0.5 McFarland standard (~1.5x108 cfu/mL). A total of 45 toothbrush heads were contaminated with MRSA by submerging in 5mL of bacterial culture and vortexing for three minutes. Toothbrush heads were then stored for 24 hours under a thymol vapor-emitting toothbrush cover (Steripod), standard plastic cover with ventilation holes (Coghlan’s), moisture-absorbent cover (IntelliDent Toothbrush Shield), or ultraviolet light sanitizer (Docooler). Toothbrush heads were vortexed for 15s in 5mL of sterile 0.9% sodium chloride solution, and serial dilutions were performed prior to spiral plating on blood agar. A positive control was included in which toothbrush heads were immediately vortexed to remove bacteria following contamination with the inoculum. Colony-forming units (cfu) were enumerated after overnight aerobic incubation at 37oC. All assays were performed in triplicate. RESULTS: Significant reductions (p<0.001) in MRSA cfu were observed among toothbrush heads stored under all four experimental conditions, compared to the positive control. Survival of MRSA on toothbrush heads stored under standard plastic covers was significantly greater than those on toothbrush heads stored under the thymol vapor-emitting cover (p=0.006), moisture-absorbent cover (p=0.006), and UV sanitizer (p=0.011). Survival of MRSA (~4%) was equivocal on toothbrush heads stored under the latter three conditions. CONCLUSIONS: Survival of MRSA was significantly lowered on toothbrushes stored under the thymol vapor-emitting cover, moisture-absorbent cover, and UV sanitizer. None of the toothbrush covers were able to completely eradicate MRSA following a storage period of 24 hours.