Question
Candida infection
Answer
Candida infection (candidiasis) is caused most commonly by Candida albicans, part of normal human commensal flora, becoming pathogenic when local or systemic host defences are compromised.
Predisposing factors: broad-spectrum antibiotic use (disrupting competing bacterial flora), immunosuppression (HIV/AIDS, corticosteroids), diabetes mellitus, indwelling catheters/devices, and pregnancy.
Clinical spectrum:
- Mucocutaneous — oral thrush (white curd-like plaques), vulvovaginal candidiasis, cutaneous intertrigo.
- Oesophageal candidiasis — an AIDS-defining opportunistic infection at low CD4 counts.
- Invasive/systemic candidiasis — candidaemia and disseminated disease in critically ill/immunocompromised or catheterized patients.
Laboratory diagnosis: direct microscopy (KOH/Gram stain) showing budding yeast with/without pseudohyphae; culture on Sabouraud dextrose agar; germ tube test — rapid identification of C. albicans (germ tube formation in serum at 37°C); chlamydospore formation on cornmeal agar; CHROMagar for rapid speciation; blood culture for invasive disease.
Treatment: topical/oral azoles for mucocutaneous disease; echinocandins or amphotericin B for invasive disease, given rising azole resistance in some non-albicans species (e.g., C. glabrata, C. krusei, C. auris).