Candida
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Background
Candida species are commensal fungi commonly found on human skin and mucous membranes, including the mouth, throat, gastrointestinal tract, and vagina. In healthy individuals, they exist without causing harm. However, under certain conditions, such as immunocompromise or antibiotic use, they can overgrow leading to infection i.e. they are opportunistic pathogens. Candida albicans is the most common species to cause infection.Risk factors for Candida infection:
- Immunocompromise e.g. chemotherapy, organ transplant recipients, HIV/AIDS, long term steroid use
- Antibiotic use: Broad-spectrum antibiotics can disrupt the normal bacterial flora, reducing competition and allowing Candida to proliferate.
- Pregnancy
- Diseases where the barrier function of the skin is disturbed e.g. psoriasis and eczema
- Endocrine diseases such as diabetes mellitus
- Cancer or malnutrition
Clinical manifestations:
- Oral and oesophageal candidiasis (thrush): Characterised by white plaques to the tongue, throat, and buccal mucosa accompanied by pain and sometimes difficulty swallowing. Inhaled corticosteroid use may increase risk.
- Vaginal candidiasis: Presenting symptoms include vaginal itching, soreness, abnormal discharge, and discomfort during intercourse or urination.
- Candida may colonise urinary catheters leading to UTI.
- Skin: May manifest as intertrigo (skin fold infections), napkin dermatitis (nappy rash) or nail infection.
- Invasive candidiasis (candidemia): Most commonly occurs in critically ill (ITU) or neutropenic patients. May be result of line infection (see below). Fungal endocarditis is a potential complication
Implications of venous catheter and line infection:
Central venous catheters are a significant risk factor for candidemia. Candida can colonise these devices, leading to bloodstream infections. Such infections are associated with increased morbidity and mortality, prolonged hospital stays, and higher healthcare costs.
Central venous catheters are a significant risk factor for candidemia. Candida can colonise these devices, leading to bloodstream infections. Such infections are associated with increased morbidity and mortality, prolonged hospital stays, and higher healthcare costs.
Diagnosis
Diagnosing Candida infections typically involves microscopy and culture to identify oval, Gram-positive cells with budding spores and hyphae. PCR tests are not widely used. The presence of Candida in cultures does not always indicate infection, therefore, laboratory results must be interpreted alongside clinical features to distinguish between colonisation and active infection.As candida is part of the normal flora growth on culture alone doesn't warrant treatment unless correlated with clinical findings.
Management
Treatment depends on the site and severity of infection. Typical treatments are shown below:- Cutaneous candidiasis: topical imidazoles e.g. clotrimazole or miconazole
- Vulvovaginal: topical clotrimazole (cream or pessary) or oral fluconazole (contraindicated in pregnancy)
- Oral candidiasis: nystatin mouthwash or oral fluconazole
- Invasive candidiasis: Primary treatment depends on immune status of patient and presence of complications e.g. endocarditis. Common first line treatments include the echinocandin antifungal medications caspofungin or micafungin given as an intravenous infusion. IV amphotericin B, IV fluconazole or IV voriconazole may also be used.