Need help with washing my dermaroller

The nurse at my derma's said that just washing your dermaroller in running water is enough. But my brother and another friend says that I should clean it in a sterlising alcohol because it may traces of blood and that could cause infection when used again. I got confused and so haven't used a dermaroller since then (it's been 1 week since my first use; my first time of using a dermaroller, the nurse assisted me). Now, no matter which medicals I go to buy a sterlising alcohol, they say that they don't have. One told me that I have to go to a surgical shop to buy one. Now please guide me, 1. Whether water is enough or should I buy a sterlising alcohol? 2. If I have to buy a sterlising alcohol, where should I buy one? 3. Also, which brand of sterlising alcohol, if there are any, would you prefer me? Thanks!