Mucosal Candidiasis

Updated: Aug 28, 2017
  • Author: Surbhi Gupta; Chief Editor: William D James, MD  more...
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Overview

Background

Candidiasis describes a group of fungal infections involving the skin and mucous membranes. Infection is caused by Candida species, primarily Candida albicans. [1] C albicans is a dimorphic fungus that can asymptomatically colonize the oral or genital mucosae in healthy individuals. [2] Oral colonization is estimated in 50% of healthy adults, [3] while genital colonization is seen in 21% of women. [4] When the local ecology is disturbed, or where there is an immune defect, Candida overgrowth may lead to an opportunistic infection. The mucosal surfaces primarily affected by candidiasis are the oral cavity, esophagus, angles of the mouth, and genitals (causing vulvovaginitis in females, balanitis in males).

Oral candidiasis may present as either white or erythematous lesions and either an acute or chronic infection. [5] Thus, the presentations can be divided into the following four subtypes:

  • Acute pseudomembranous candidiasis (thrush): The classic multiple white-flecks on the tongue, buccal mucosa, and palate
  • Chronic hyperplastic candidiasis: Thick white plaques on the buccal mucosa and labial commissures
  • Acute atrophic (erythematous) candidiasis: Erythematous patches on the palate
  • Chronic atrophic candidiasis (denture stomatitis): A form of erythematous candidiasis, resulting from poorly fitted dentures causing a burning, sore mouth

There are also conditions that may predispose individuals to chronic, multifocal infections from Candida. This can lead to syndromes such as chronic mucocutaneous candidiasis (CMC).

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Pathophysiology

C albicans is a dimorphic fungus that asymptomatically inhabits the mouths of almost 50% of the population. Overgrowth of Candida is protected against by local T cells and interleukin (IL)–17. [6] Thus, when immunity is compromised, growth proceeds unchecked and leads to opportunistic infections.

Candidiasis is seen in people with altered ecology, which in oral cases can be attributed to dental appliances, xerostomia, antimicrobials, nasopharyngeal steroids, or oral cancer. Impaired systemic immunity is another major cause of infection, notably in patients who are on immunosuppressive therapy, infected by HIV, or have diabetes. [7, 8]

C albicans is the predominant causal organism of most candidiasis. Other species, such as Candidatropicalis and Candidastellatoidea, more often appear in persons who are severely immunocompromised.

Secreted aspartyl proteinases (SAPs) are proteins secreted by Candida that contribute to virulence by facilitating invasion and inflammation. The prevacuolar protein sorting gene, VPS4, is required for extracellular secretion of SAPs, and it is a key component of the virulence of Candida. [9] Additionally, studies have shown that women with vulvovaginal candidiasis have higher levels of SAPs in their vaginal fluid. [10]

In those with dental devices, Candida, upon attachment, can form a small subcolony of persister cells. These cells have been shown to be highly resistant to antimicrobials, and they provide a mechanism for the recurrent formation of biofilms. [11]

Chronic mucocutaneous candidiasis

Chronic mucocutaneous candidiasis (CMC) describes a group of rare syndromes, in which persistent mucocutaneous candidiasis responds poorly to topical treatment. It is associated with immune defects, particularly in T-cell, dendritic cell, and T-helper 17 (Th17) cell function. Studies have demonstrated specific signals that when compromised, cause defects in the response to candidal antigens. Identified defects include overproduction of IL-6, underproduction of IL-23, and deficiency of IL-17.

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Epidemiology

Risk factors

There are many risk factors that increase the incidence of candidiasis. Immunosuppression is the most significant of these, and it can be due to diabetes, antibiotics, immunosuppression, systemic steroid use, and HIV infection, among others.

  • Immunocompromise: Increased carriage rates are seen in several conditions, including HIV infection, diabetes, systemic steroid use, aerosolized steroid use, immunosuppression, and malignancy
  • Hyposalivation: Increases carriage of Candida and can be due to drug effects (antipsychotics), Sjögren syndrome, radiotherapy, or chemotherapy
  • Poor oral hygiene: Candida counts increase during sleep but are reduced by eating and brushing the teeth
  • Dentures: Removal and reinsertion of dentures cause increases in salivary candidal counts, suggesting that plaque on the dentures harbors C albicans
  • Missing teeth: Being edentulous increases the overlap of skin at the corners of the mouth, increasing the risk for angular cheilitis formation
  • Smoking: Increases Candida carriage by 30-70%
  • Antibiotic use: Increases carriage of Candida
  • Vitamin deficiencies: Higher association of candidiasis with vitamin B-12 and iron deficiency
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Prognosis

The prognosis is good for most infections in the immunocompetent host, but in patients who are immunocompromised, antifungal resistance is commonplace. Oral candidiasis may predispose individuals to esophageal spread. Systemic spread is rare, but can occur in the severely immunocompromised.

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Patient Education

For patient education resources, see the following:

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