Staphylococcus, is what we term a commensal bacterial, which means it "lives with us.
" It lives on our skin, in our nose, mouth, throat, etc. A culture that says "light growth" means that it has either overpopulated the site in question or is growing at a site that should be sterile (i.e. absent of bacteria). Coagulase negative indicates it is not a strain that causes serious disease