Thrush (Oral Candidiasis)

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Candida albicans accounts for about 90% of human yeast infections.  Other species that may cause oral thrush include C. glabrata, C. krusei, and C. tropicalis, although C. albicans is often present with them.  Candidal infections most commonly affect the skin (especially the diaper area and abdominal fat folds), nails, mouth, and vagina, but can also present in the ear canal, lungs, bladder, eyes, CNS, heart, liver, or other parts of the GI tract.  This summary focuses on oral candidiasis, or thrush.

 

Pathophysiology

  • Thrush represents an overgrowth of yeast when either normal host immunity or normal host flora has been disrupted.
  • Yeast overgrowth on the oral mucosa causes the epithelial cells to desquamate.
  • Bacteria, keratin, and necrotic tissue accumulate and form a pseudomembrane.
  • Oral candidiasis is common in infants.  Neonates with thrush have usually been colonized when they passed through the birth canal, but other sources of transmission may include colonized breasts, hands, or bottle nipples.
  • Thrush can also develop as an adverse effect from inhaled corticosteroids for asthma.
  • Immunosuppressed patients may also develop candidal esophagitis.

 

Epidemiololgy

  • Candida albicans is a common inhabitant in normal adult gastrointestinal tracts and vaginas. During pregnancy, the colonization rate may be 33%.
  • 10% of normal infants are colonized in the GI and respiratory tract at 5 days of age and this rate increases in preterm infants. The skin is usually colonized at 2 weeks of age.
  • Thrush occurs throughout the world and is particularly common in populations with poor nutrition.  It occurs equally in males and females.
  • Thrush usually appears about 1 week of age and diaper dermatitis at 3-4 months.
  • Thrush is a disease of infants, and in older children it is associated with the use of antibiotics.
  • Recurrent or persistent thrush should raise the suspicion of a possible underlying immunodeficiency syndrome.  Thrush can be the first presenting sign of HIV infection.

 

Clinical presentation

  • White curdish like lesions on the buccal mucosa, tongue, palate, and gingiva. The lesions are difficult to scrape off and this differentiates it from milk. After scraping, there is an erythematous base and some bleeding.
  • Infants with thrush may present with pain, poor feeding, or fussiness, but patients are more often asymptomatic and thrush presents no interference with eating. 
  • Esophagitis due to Candida infection may present with chest pain and poor feeding.
  • Oral candidiasis may be associated with diaper candidiasis, so it is always important to check for diaper rash when thrush is present.

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Causes

  • Premature infants are especially predisposed to thrush due to their immature immune system.
  • In older patients who are immunocompetent, predisposing factors are often present, such as a recent course of antibiotic therapy that disrupts the normal flora, or steroid use.
  • Immunosuppressed patients are more susceptible to oral candidiasis, as well as cutaneous and systemic infections.

 

Treatment

  • If left untreated, oral candidiasis will resolve in 3-8 weeks, but in most instances topical antifungal agents are used. Mild cases may be watched without treatment.
  • Nystatin oral suspension is the drug of choice for oral candidiasis. Various reports have reported cure rates between 50-80% on standard 100,000 units per dose 4 times a day. May have to double the dose or apply it directly to the lesions with a cotton swab. Nystatin does not adhere well to the lesions and is swallowed rapidly and this interferes with its efficacy.
  • Older children can swish nystatin suspension around in their mouth and swallow it.  For infants, parents can apply 1-2ml of the solution inside each cheek between meals, or directly to the lesions with a swab.
  • Gentian violet has been shown to be effective as a second-line agent for oral candidiasis resistant to nystatin, but is messy to use and should not be swallowed.
  • These oral antifungals have little to no systemic absorption, so there are minimal adverse effects.
  • In nursing mothers, the breast may be a reservoir for the yeast so that the application of a topical antifungal between feeds to the breast may help eradicate the infection.
  • Always continue to check for diaper dermatitis because often associated with oral monilia infection

 

References

  • Hoppe, Jorg and the Antifungal Group. Treatment of oropharyngeal candidiasis in immunocompetent infants: a randomized multicenter study of miconazole gel vs.nystatin suspension. The Pediatric Infectious Disease Journal. March 1997.
  • Kalyoussef et al. Pediatric Candidiasis. Medscape Reference. July 2010.
  • Tolan et al. Thrush. Medscape Reference. January, 2011.

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