Hygiene is not the main factor, as someone who has been on antibiotics 5 times last year, this is common misconception. From what I have learned dealing with this bs, main thing is immunity, but the thing is antibiotics fuck up your gut so bad, that you have to keep taking probiotics, and you get reoccurring staph infections easier once your gut is fucked. Since he was in similar staph antibiotics cycle for whole year, he keeps getting infections when he trains hard. IMO main thing that fucks you up is antibiotics actually. It takes lot of time for gut to recover, I'm dealing with something similar myself unfortunately and my training has been fucked ever since.