Staph. aureus and Streptococci are ubiquitous creatures. They normally colonize human skin and throat, respectively. It's ok to get the flu 2 maybe 3 times a year, and Staph may cause a gastroenteritis. The frequeny of these infections should decrease with time, however, as your immune system develops strategies to combat them. If this is not the case then consider that there might be a problem (are you underweight? do you over exert yourself? etc).