What causes oral candidiasis (thrush) in infants?

From the Guidelines

Oral candidiasis (thrush) in infants is primarily caused by an overgrowth of the Candida albicans fungus, which naturally exists in small amounts in the mouth and digestive tract. This condition appears as white patches on the tongue, gums, and inside of the cheeks that don't wipe away easily. The primary risk factors for developing thrush in infants include prematurity, low birth weight, and exposure to antibiotics, which can disrupt the normal oral flora [ 1 ].

Key Factors Contributing to Thrush in Infants

• Prematurity and low birth weight [ 1 ]
• Exposure to antibiotics [ 1 ]
• Poor oral hygiene
• Weakened immune system
• The warm, moist environment in a baby's mouth provides ideal conditions for fungal overgrowth, especially when combined with the sugars from milk or formula that feed the yeast

Importance of Proper Treatment and Prevention

To treat thrush effectively, it's essential to apply an antifungal medication, such as nystatin oral suspension, and to sterilize pacifiers, bottle nipples, and breast pump parts after each use [ 1 ]. If breastfeeding, mothers should be treated simultaneously with an antifungal cream to prevent reinfection. Fluconazole may be prescribed for more severe cases, but its use should be carefully considered due to potential risks and limited pharmacokinetic data in premature infants [ 1 ]. Regular follow-up of neurodevelopmental parameters is crucial in infants who receive antifungal therapy, especially fluconazole [ 1 ].

From the Research

Causes of Oral Candidiasis in Infants

• Oral candidiasis, also known as thrush, is a fungal infection caused by an overgrowth of Candida species, with Candida albicans being the most common species 2, 3, 4.
• In infants, oral candidiasis can occur due to an imbalance in the normal flora of the mouth, leading to an overgrowth of Candida albicans 2.
• Factors that may contribute to the development of oral candidiasis in infants include:
  • Maternal mastitis and the use of antibiotics, as found in a study of 32 healthy, full-term infants 5.
  • Impaired salivary gland function, drugs, and extremes of life, as mentioned in a review of oral candidiasis 4.
• The exact cause of oral candidiasis in infants may not always be clear, as seen in a study where C. albicans was not discovered in babies with clinical thrush 5.

Risk Factors and Associations

• Certain factors may increase the risk of developing oral candidiasis in infants, including:
  • Maternal mastitis and the use of antibiotics 5.
  • High carbohydrate diet, smoking, diabetes mellitus, Cushing's syndrome, malignancies, and immunosuppressive conditions, as mentioned in a review of oral candidiasis 4.
• The presence of white patches on the oral mucosa is often associated with oral candidiasis, but the aetiology of these patches may not always be clear 5.