Understanding Oral Candidiasis or Oral Thrush

Oral Candidiasis or Oral Thrush is a fungal opportunistic infection of the mouth caused by the overgrowth of Candida. Most commonly, candida albicans. It is normal to have small amounts of commensal candida in the mouth, however when there’s an imbalance it can grow out of control resulting in this fungal infection. The pathophysiology of oral candidiasis is related to an impaired host immunity. Because your immune system is not fighting these candida species, the commensal, or normal candida in the mouth start to grow rapidly, especially considering the mouth is a warm and moist environment. This overgrowth leads to the formation of a pseudomembrane, especially on the tongue which makes it difficult to remove. The risk factors for pathological overgrowth of candida can be categorised into systemic factors and local factors: Systemic factors include: Extremes of age – young children and the elderly, immunocompromising conditions like uncontrolled diabetes, malnutrition, existing concomitant infections, long-term steroid treatment and some antibiotics Local factors include: dentures, Smoking, Inhaled corticosteroids Poor oral hygiene and salivary gland hypofunction. There are many forms of oral candidiasis based on their clinical characteristics and potential causes: These are some of the most common types: Pseudomembranous candidiasis: also known as thrush, this is the most common type of candidiasis and it appears as soft white, painless plaques on the mucosa that can sometimes be wiped off leaving a red, raw or bleeding and painful surface. The buccal mucosa, palate and tongue are common locations but it can spread. For example, if the dorsum of the tongue is affected, then the palate can also be affected, in the same way, it can also spread to the throat in the oropharynx. There is Erythematous candidiasis and as the name suggests, erythema means red, so you get sensitive red lesions on the tongue and palate. And finally, there is Hyperplastic candidiasis, which is similar to pseudomembranous, whereby it is a white, painless plaque, but in this case, it cannot be removed and can appear nodular, which means it is sticking out a little bit. This can sometimes resemble leukoplakia or oral cancer. Note that there are other types of candidiasis, but they are extremely rare. When someone does have a candida infection, they can have candida associated lesions, these include: Denture stomatitis: which is a sensitive, red area caused by poor denture hygiene Median rhomboid glossitis, which is loss of papilla and redness in the middle of the tongue dorsum And finally, angular chelitis or angular stomatitis which is painful redness and fissuring or cracking of the corners of the mouth. It is generally diagnosed clinically by visual inspection and assessment of risk factors. Which are generally a giveaway, especially if a patient is immunocompromised. Sometimes, a specialist referral is required, especially if it is suspected that a more rare form of candidiasis is present. The specialist would take a biopsy to look at the lesion under a microscope for a more accurate diagnosis. Management principles rely on addressing the underlying factors, for example, smoking cessation if someone is a smoker, and doing a mouth rinse after using a corticosteroid inhaler. Other principles include having good oral hygiene, and that includes denture hygiene as well. If preventative management does not work, then antifungal medications can be considered. These medications can be in the form of a topical cream, a lozenge or a pill. Examples of these are: Nyastatin, amphotericin and miconazole To summarise, oral candidiasis is a condition that occurs when the immune system is suppressed and the commensal or native candida species, start growing uncontrollably. There are many risk factors, local and systemic which contribute to various types of candidiasis, mainly through immunosuppression. Risk factor assessment and clinical examination are required for a diagnosis, with some cases requiring biopsy. Management is through alleviating risk factors as a first line and second line being antifungal therapy.