Staph infections such as mrsa and cdiff can't really become airborne. mrsa can be transmitted through sputum(flem) but the person would have to cough directly on an open wound on you. Cdiff is really only transmitted through stool so unless you're handling stool and/or your operating in an unsterile environment, the chances of getting it are rare.
MRSA is the one you gotta worry about though. It can live on any surface for I think an average of 10 days. It also never goes away kinda like herpes. It can be put into a dormant state but can flare up at any time especially is the persons immune system is compromised.
It can either be isolated to the persons blood and/or urine or can be topical. The topical type can literally eat through clothing. It can also completely upset someones blood sugar is they are diabetic.
You all can thank the doctors who have over prescribed antibiotics. If your ki has a cold, the last thing you should give them is amoxycillin. Why would you prescribe an antibiotic for a viral issue? It makes no sense and I don't know how it made sense 20 years ago. As long as the kid isn't running an excessively high fever (102+), let them ride it out. It can only make their immune system stronger.