Microbiology · Yeasts and yeast-like fungi
Candida albicans !
- Fungus
- Exam priority: high
A yeast living in the mouth, gut and vagina; causes thrush, vaginitis and hospital bloodstream infection. Its relative C. auris is multidrug resistant.
Updated 2026-11-01
Also called: Candida, candidiasis, thrush, Candida auris (Candidozyma auris)
At a glance
- Shape
- Oval budding cells; pseudohyphae in chains
- Family
- Debaryomycetaceae (Saccharomycetales)
- Type
- Yeast that also forms pseudohyphae and true hyphae
- Stain
- KOH or Gram: yeasts with pseudohyphae (Gram positive); PAS and silver (GMS) in tissue
- Size
- Yeasts of about 4–6 µm
Morphology
- Oval yeast that divides by budding
- Forms pseudohyphae (elongated buds that stay attached) and true hyphae
- Positive germ tube test: in serum at 37 °C it forms a tube with no constriction at its base
- White creamy colonies on Sabouraud agar
Transmission
- Almost always endogenous: part of the person's own flora of mouth, gut, skin and vagina
- Reaches the blood through central venous catheters, abdominal surgery or damaged mucosa
- C. auris spreads in hospitals on hands and contaminated surfaces (bedrails, blood pressure cuffs) and from colonised patients
Reservoir: Human mucosa and skin; For C. auris: colonised skin (armpits, groin) and the patient's surroundings
Isolation precautions
What the care team adds to standard precautions.
- Standard
Virulence factors
- Switch from yeast to hypha, which lets it penetrate epithelium
- Adhesins that bind it to cells and plastics
- Biofilm on catheters, which shields it from antifungals and host defences
- Enzymes (aspartyl proteases, phospholipases) that damage tissue
Diseases it causes
- Vulvovaginal candidiasis: thick white discharge and itching; more common after antibiotics, in pregnancy and with poorly controlled diabetes Vulvovaginal candidiasis →
- Oropharyngeal candidiasis (thrush): white plaques that scrape off; in infants, inhaled corticosteroid users and HIV
- Invasive candidiasis and candidemia: fever in a hospitalised patient with a catheter; can seed the eye, heart and bone Candidiasis: oral, oesophageal and invasive →
Clinical picture
- Candida esophagitis: painful swallowing; in advanced HIV it is an AIDS-defining illness
- Intertrigo and diaper candidiasis: red plaques with satellite lesions
- Endophthalmitis in candidemia: looked for with a fundus exam
Diagnosis
- KOH mount: yeasts with pseudohyphae
- Blood culture: the main method for candidemia
- Species identification (MALDI-TOF) and susceptibility testing guide treatment
- Serum beta-D-glucan supports the diagnosis but is not specific
- C. auris is often misidentified as C. haemulonii by automated systems: confirm with MALDI-TOF or molecular methods
Treatment
Mucosal disease: topical or oral azoles (clotrimazole, fluconazole) or nystatin. Candidemia: echinocandins (caspofungin, micafungin) first, stepping down to fluconazole if the strain is susceptible; amphotericin B as an alternative. C. glabrata and C. krusei respond less to fluconazole, and C. auris can resist all three classes.
Drug class only; doses and regimens are set by the clinician from the current guideline.
In Pharmacology:
Prevention
- Care and early removal of central lines
- Prudent use of antibiotics and antifungals
- Hand hygiene and cleaning with disinfectants effective against C. auris (for example, chlorine-based)
- For C. auris: contact precautions, a single room and skin-swab screening of contacts
Test yourself
Think of the answer, then tap the question to see it.
Which simple test tells Candida albicans apart from other Candida species?
The germ tube test: in serum at 37 °C C. albicans forms a tube within a few hours.
Which antifungal class is first choice for candidemia in a seriously ill adult?
The echinocandins (caspofungin, micafungin, anidulafungin).
Which isolation precautions does a patient with Candida auris need?
Contact precautions on top of standard ones, with strict environmental cleaning, because it spreads on hands and surfaces.
Why did Colombian labs at first fail to recognise Candida auris?
Automated systems identified it as C. haemulonii; MALDI-TOF or molecular methods are needed.
Related
Related conditions
← Back to the group: Yeasts and yeast-like fungi
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Candidiasis Basics (CDC, 2024); Clinical Overview of Invasive Candidiasis (CDC, 2024); Notes from the Field: Surveillance for Candida auris — Colombia, September 2016–May 2017 (CDC, 2018); Infección por Candida auris afecta principalmente a población hospitalaria con condiciones especiales de salud (Instituto Nacional de Salud (INS) Colombia, 2023).
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Representative model, for educational purposes only.