These things are nasty. My cousin was in a wreck and damaged his spleen, which of course, helps boost the immune system. He's had MRSA boils a couple of times since then.
He's a healthy guy otherwise. He gets plenty of exercise, etc., but he's always on the lookout to avoid infections because of his spleen damage. I don't remember if he takes flu shots, or if he can because he's considered immune compromised. His doctor said with this last round of boils, he was lucky to get them in time, that the infection was really aggressive and the antibiotics took a while to start working. At least he works for his grandfather, so he won't lose his job if he's in the hospital. It's happened to some people I know.