MRSA is a serious but controllable infection that occurs in some children because of their somewhat weaker immunity or exposure to these unusual germs. Occasionally a child with a history of super-infections will ACTUALLY be sufferring from a real immune deficiency
or what is called as "immotile cilia" syndrome. Your doctor might advice on the other hand to simply not worry too much about these rare things and go on with the current medicines. However, I strongly recommend that you speak with him/her about checking the immune functions as soon as possible.