Medical-type swabs are often used to take microbiological cultures. Pharmaceutical grade cotton swabs are necessary for medical applications. These medical grade swabs are rubbed onto or into the infected area, then wiped across the culture medium, such as an agar plate, where bacteria from the swab may grow. They are also used to take DNA samples, most commonly by scraping cells from the inner cheek in the case of humans. They can be used to apply medicines to a targeted area, to selectively remove substances from a targeted area, or to apply cleaning substances like Betadine. They are also used as an applicator for various cosmetics, ointments, and other substances.