Causes of Candidal Thrush in Babies
Candidal thrush in babies is primarily caused by Candida albicans, which can colonize the oral cavity due to multiple risk factors including prematurity, exposure to broad-spectrum antibiotics, and maternal vaginal candidiasis. 1
Primary Risk Factors
Neonatal Factors
Prematurity: Smaller gestational age significantly increases risk
- Neonates at 23-24 weeks: 10-20% incidence of invasive candidiasis
- Neonates at 25-27 weeks: 5-10% incidence
- Neonates ≥28 weeks: <5% incidence 1
Low birth weight: Directly correlates with thrush risk
- Infants <750g: >10% incidence
- Infants 750-1000g: 5-10% incidence
- Infants >1000g: <5% incidence 1
Immature immune system: Newborns have underdeveloped immune responses that cannot adequately control fungal colonization
Medical Interventions
- Antibiotic exposure: Broad-spectrum antibiotics (especially third-generation cephalosporins and carbapenems) disrupt normal oral flora 1
- Endotracheal intubation: Creates trauma to mucous membranes allowing fungal invasion
- Parenteral nutrition: Alters normal gut flora and immune function
- Use of antacids: Reduces stomach acidity that normally helps control fungal growth 1
Maternal Factors
- Maternal vaginal candidiasis: Can transmit Candida to baby during delivery 1
- Maternal mastitis: Significantly associated with infant thrush (p=.001) 2
- Breastfeeding-related transmission: Candida can be passed between mother's breasts and baby's mouth during feeding 3
Pathophysiology
Candida albicans is the most frequent species causing oral thrush in neonates 1, though other species like Candida parapsilosis and Candida tropicalis can also be involved. Unlike in adults, Candida glabrata and Candida krusei are infrequent causes in neonates 1.
The pathogenesis involves:
- Initial colonization of the oral mucosa
- Adhesion to epithelial cells
- Proliferation when local or systemic factors disrupt normal flora balance
- Invasion of mucosal surfaces in susceptible hosts
Clinical Considerations
Diagnostic Challenges
- Clinical diagnosis is often made based on white patches on oral mucosal surfaces 2
- However, recent research suggests that not all white patches are caused by Candida species 2
- In one study, C. albicans was not discovered in babies with clinical thrush, suggesting other potential etiologies 2
Treatment Implications
- Treating maternal vaginal candidiasis prior to delivery may prevent subsequent neonatal colonization 1
- Avoidance of horizontal transmission in neonatal units requires rigorous infection control measures 1
- Both mother and infant may need simultaneous treatment when breastfeeding is involved 3
Prevention Strategies
- Rational use of broad-spectrum antibiotics
- Rigorous infection control in neonatal units
- Treatment of maternal vaginal candidiasis before delivery
- Careful monitoring of high-risk infants (premature, low birth weight)
- Proper hygiene practices during feeding and care
Understanding these risk factors and mechanisms allows for targeted prevention and early intervention strategies to reduce the incidence and severity of candidal thrush in babies.