Candidiasis
A primary or secondary mycotic infection caused by
members of the genus Candida.
The clinical
manifestations may be acute, subacute or chronic to
episodic. Involvement may be localized to the mouth,
throat, skin, scalp, vagina, fingers, nails, bronchi,
lungs, or the gastrointestinal tract, or become systemic
as in septicaemia, endocarditis and meningitis.
Distribution: World-wide.
Candida
MOST COMMON invasive fungal infection in
immunocompromised patients
4th most common cause of nosocomial blood stream
infection
Species implicated in human disease most often:
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C. albicans
C. tropicalis
C. parapsilosis
C. krusei (fluconazole resistant)
C. glabrata
C. lusitaniae (amphotericin B resistant)
2
Candida
• Thick cell wall of mannan and glucan
polysaccharides
• Unicellular, budding (asexual)
reproduction (blastospores)
– Filament formation
• Pseudohyphae (buds stay attached, constricted,
chains of elongated blastospores)
• Hyphae (buds germinate)
3
Cell wall Candida albicans
4
Candida
Human commensal (endogenous)
– skin, gastrointestinal, genitourinary tracts
– 5 - 15% carriage rate in normal people
– increased carriage with use of antibiotics
Environmental (exogenous)
– much less common
– food, animals, soil hospital environment
– outbreaks have occurred
5
Candida - Clinical
• Mucous membrane infections
– Thrush (oropharyngeal)
– Esophagitis
– Vaginitis
• Cutaneous infections
– Paronychia (skin around nail bed)
– Onychomycosis (nails)
– Diaper rash
– Balanitis
– Chronic mucotaneous candidiasis
– Children with T-cell abnormality
6
Candida - Clinical
• Urinary tract infection
• Fungemia
• Disseminated (systemic, invasive) infection
– Immunocompromised patients
• Cancer/chemotherapy
• Neonatal candidiasis
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Endophthalmitis (eye)
Liver and spleen
Kidneys
Skin
Brain
Lungs
Bone
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Mucosal candidiasis
Oral thrush
Vaginal candidiasis
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Cutaneous candidiasis
Diaper dermatitis
Balanitis
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Cutaneous candidiasis
Onychomycosis and paronychia
Chronic mucocutaneous candidiasis
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056
057
058
059
060
061
062
063
064
065
068
069
071
075
Candida - Laboratory Diagnosis 1
• Specimens - Blood, tissue (biopsy or autopsy),
sterile fluid, urine, CSF, skin, respiratory
secretions
• Microscopy (direct on specimen - except blood
and urine)
– Gram stain, Calcofluor
• Histopathology (tissues)
– H & E - stain poorly
– GMS, PMS - stain well
25
Candida - Laboratory Diagnosis 2
• Culture (all specimens)
– Colony morphology
• White, smooth, creamy, sometimes wrinkled
– Laboratory identification
• Unique color on chromagar
• Chlamydospore production (terminal vesicle)
• Germ tube production (in horse serum)
– beginning of true hypha (no constriction)
» C. albicans - Germ tube positive
» Other Candida - Germ tube negative
• Carbohydrate assimilation and fermentation (API 20C, Vitek2,
RapID and reference)
• Urea and nitrate
• Microscopic morphology on Cornmeal Tween 80
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Candida species
Candida albicans
Sabouraud Agar
Morphology: Creamy white yeast,
may be dull, dry irregular and
heaped up, glabrous and tough
Chromagar
producing green pigmented colonies
on specially designed medium to
speciate certain yeasts based on
color they produce
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Candida species
Germ tube: inoculation of yeast in horse
serum incubated at 370C for 2 to 3 hours
Germ Tube: Positive
Germ tube is a continuous filament
germinating from the yeast cell without
constriction at the point of attachment.
e.g. C. albicans, C. dubliniensis
Germ Tube: Negative
Shows constriction at the attachment site
e.g. other Candida species, esp. C. tropicalis
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Candida species
Candida albicans
Oxgall Agar
large round and thick
walled chlamydospores
x400
Cornmeal Agar
clusters of
blastospores along
pseudohyphae at regular
intervals
x1000
x400
x1000
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076
077
078
079
080
081
082
083
084
086
087
092
093
Candida - Treatment
• Remove infected intravenous lines
• Antifungal therapy for systemic infection
– Amphotericin B IV
– Azoles (fluconazole, itraconazole, voriconazole,
posaconazole) orally, intravenous
– Flucytosine (only with Ampho B because of
resistance)
– Echinocandins (caspofungin, micafungin)
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Candida antifungal resistance
• Primary (inherent) resistance
– C. lusitaniae (amphotericin B)
– C. glabrata (fluconazole)
– C. krusei (fluconazole)
• Secondary (acquired) resistance
– Fluconazole, other azoles
– Amphotericin B
– 5-FC
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Candida antifungal susceptibility testing
• Testing methodology
– Reference broth microdilution (CLSI)
– Commercial broth microdilution with alamar blue
(Sensititre, YeastOne)
– E-test
– Disk diffusion (CLSI
– Vitek 2
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Candida antifungal susceptibility testing
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Candida antifungal susceptibility testing
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