Dx & treatments 4 angular cheilitis during long term abx treatment. R there tests 2 tell if it's caused by fungus, bacteria or both? Best treatments?

Wrong question. Angular cheilitis is due to SALIVA. While treatment against yeast and staph may sometimes be useful, they are of peripheral interest. Most of these are in older people who have lost teeth. They have a deep fold of skin which draws in saliva by capillary action, usually during sleep. Protection of the skin from saliva is key. Apply vaseline [Aquaphor] at bedtime and several times a day. Chapstick i.
NO specific tests. Angular cheilitis can be from a number of things but mostly fungal. This also can be due to a habit. Try not licking the area and keep the area dry. I woiuld use an antifungal cream till the redness goes away and then use vaseline to keep the area moist but not irritated.
Fungal. In your case, I am most suspicious of a fungal cause because of the long term antibiotics. Try some topical anti-fungal medication prescribed by your doctor.