How does a grown man get thrush?

Thrush in Adult: One of the more common reasons is taking antibiotics. Thrush is a yeast infection in the mouth/throat. When you take antibiotics, you kill off bad &good bacteria. When these bacteria die, the ph can change and it leaves a void for the growth of other normal occurring organisms to grow, like the yeast, candida. Another reason is immune suppression, when you can't keep the yeast from growing.