An oral yeast infection, or thrush, is a fungal infection caused by the Candida albicans microorganism. Candida naturally resides in the mouth of many people, but its growth is usually kept in check by healthy bacterial flora. According to KidsHealth, a Candida infection is more common in babies and elderly people but can happen at any age. Infection occurs during an overgrowth of Candida, and it can occur for several reasons.
Antibiotic Use
Long-term antibiotic use kills beneficial bacteria of the mouth, along with the offending bacteria. Because there are not enough good bacteria to control the growth of Candida, they're able to grow without having to compete for resources with the normal flora. The white plaques of oral thrush then start to appear on the tongue, cheeks and palate.
Immunosupression
A working immune system usually prevents excessive growth of Candida in healthy people. When the immune system becomes compromised, Candida can grow throughout the mouth. Because the immune system of infants isn't fully developed, oral yeast infections are common. This also frequently occurs with people with conditions that weaken the immune system such as HIV, cancer or malnutrition.
Dry Mouth
Saliva keeps the mouth moisturized and healthy. Columbia University indicates that people without adequate saliva flow are more prone to develop oral yeast infections. A dry mouth upsets the natural balance of microorganisms in the oral cavity. Dry mouth is a side effect of some medications and radiation treatments to the head or neck.
