Candidiasis is a fungal infection caused by Candida species, most commonly Candida albicans. It can affect various parts of the body, including the mouth (oral thrush), skin, genitals (vaginal or penile candidiasis), and bloodstream (invasive candidiasis). Though it often causes mild infections, it can become serious, especially in immunocompromised individuals.
Causes
Candidiasis is caused by an overgrowth of Candida fungi, which normally live harmlessly on the skin and mucous membranes. Overgrowth can occur when the body’s immune system is weakened or the normal balance of microorganisms is disrupted. Common triggers include antibiotic use, high sugar intake, poor hygiene, or underlying health conditions.
Pathophysiology
Candida species are opportunistic pathogens. When the body’s natural defences are lowered, these fungi adhere to mucosal surfaces or skin, form biofilms, and invade tissues. They switch from yeast to hyphal form, increasing their ability to penetrate tissues and evade immune responses. In systemic infections, Candida can enter the bloodstream and spread to organs.
Signs and Symptoms
Symptoms vary depending on the site of infection:
- Oral candidiasis: White patches on the tongue, inner cheeks, or throat; redness; soreness; difficulty swallowing.
- Vaginal candidiasis: Itching, burning, thick white discharge, redness, discomfort during urination or sex.
- Penile candidiasis: Redness, itching, white patches, and discomfort.
- Skin candidiasis: Rash in warm, moist areas (e.g., groin, under breasts) with itching and redness.
- Invasive candidiasis: Fever, chills, organ dysfunction—requires urgent medical attention.
Risk Factors
- Antibiotic or corticosteroid use
- Poorly controlled diabetes
- Pregnancy
- Weakened immune system (e.g., HIV, chemotherapy)
- Use of dentures or poor oral hygiene
- Wearing tight or damp clothing
- Hospitalisation or use of invasive devices (e.g., catheters, IV lines)
Investigations
Diagnosis depends on the site of infection:
- Microscopy and culture of swabs from affected area (oral, vaginal, skin)
- KOH test to identify fungal elements under the microscope
- Fungal culture to confirm Candida species
- Blood cultures for suspected invasive candidiasis
- Full blood count and inflammatory markers (e.g., CRP) in systemic cases
- Imaging (CT/MRI) if deep-seated organ involvement is suspected (e.g., in candidemia)
Management
1. Non-Pharmacological
- Maintain good hygiene and keep skin dry
- Wear loose-fitting, breathable clothing
- Avoid scented soaps or vaginal douches
- Control blood sugar levels in diabetics
- Limit unnecessary use of antibiotics or steroids
2. Pharmacological
NICE recommends antifungal treatments tailored to the type and severity of infection:
- Topical antifungals (e.g., clotrimazole, miconazole) for skin and mucosal infections
- Oral antifungals (e.g., fluconazole) for moderate to severe vaginal candidiasis or oral thrush
- IV antifungals (e.g., echinocandins like caspofungin) for systemic or invasive candidiasis
- For recurrent vaginal candidiasis, long-term fluconazole may be used under specialist guidance
3. Surgical
Surgery is rarely needed but may be required to drain abscesses in cases of invasive candidiasis or to remove infected foreign bodies such as catheters.
Complications
- Recurrent infections, particularly vaginal or oral candidiasis
- Systemic spread in immunocompromised individuals (candidemia)
- Organ dysfunction or sepsis in untreated invasive candidiasis
- Psychological impact, especially in chronic genital infections
- Resistance to antifungal medications, particularly with overuse or incomplete treatment
References
- NICE Clinical Knowledge Summaries (CKS): Candidiasis – oral and vaginal (last updated 2022)
- Public Health England: Management of Candida infections
- Royal College of Obstetricians and Gynaecologists: Guidelines on vaginal discharge
- Royal College of General Practitioners (RCGP): Fungal infections learning module
- General Medical Council (GMC): Good Medical Practice and prescribing guidelines