staph infection? newborn?

hello mamas! please no judgment here!

my three week old and i have recently been to my grandmothers house multiple times this week for dinner and to visit. she has held her and played with her. (my grandparents almost never leave the house) so we thought it would be completely safe for a visit with grandma. today.. my grandmother found out she has staph infection in a wound on her arm. she had no idea and neither did we. what should i do? so far my sweet girl is doing great. i know staph is highly contagious. what do i do?