YEASTS

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YEASTS

• Page 8

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Yeasts

• Round to oval, single cells which reproduce
  by budding

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Yeasts

• SELECTED GENERA

• Candida
• Cryptococcus

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Candidiasis

• Candida albicans
• Non-albicans species

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Ecological Niche
Candida albicans
Endogenous (mouth, gut,
vagina)
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Infections with Candida usually occur when there
is some alteration in

• Cellular immunity
• (Immunocompromised)
• Normal Flora
• (Prolonged antibiotics)
• Physiology
• (Cardiac surgery, catheter)

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CANDIDIASIS

• Skin
• Vaginitis
• Urinary tract
• Mucous membranes
• Septicemia
• Endocarditis
• Pneumonia

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CANDIDIASIS

• The fourth most common nosocomial bloodstream
  infection.

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GEOGRAPHIC OCCURENCE

• WORLDWIDE

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Clinical SpecimensCandida

• Sputum
• Scrapings from lesions
• Blood smears
• Vaginal discharge
• Urine
• Feces
• Nail clippings

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8-12 MICRONS
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Pseudomycelium
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GERM TUBES
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SEROLOGY

• There have been several antibody detection test,
  but none are significant.
• Beta-Glucan measurement is now showing promise

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Therapy

• Nystatin
• Vaginitis
• Cutaneous
• Fluconazole
• Itraconazole

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Cryptococcosis

• Cryptococcus neoformans

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Cryptococcosis

• A sub-acute or chronic infection which may
  affect the lungs or skin but most commonly
  manifests as a meningitis

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Typical clinical course

• Inhalation
• Mild pneumonia
• Vision, lethargy, headache
• Delirium, nuchal rigidity, coma
• Over a period of months
• Death if not treated

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Cryptococcus neoformans

• Spherical
• 5-10 microns
• Narrow- base
• Surrounded by polysaccharide capsule

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Cryptococcus neoformans

• Virulence factors
• Anti-phagocytic polysaccharide capsule
• Antioxidant melanin
• Ability to grow at 37 C

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GEOGRAPHICAL DISTRIBUTION

• WORLDWIDE

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Ecological Niche
Cryptococcus neoformans

• Pigeon droppings
• Chicken droppings

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Isolation of Cryptococcus neoformans from
environmental sites in South Carolina
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Cryptococcusportal of entry

• Inhalation
• inoculation

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Specimen of choice

• Cerebrospinal fluid

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Clinical Specimens
Cryptococcosis

• CSF
• Sputum
• Pus
• Biopsy material
• urine

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Serological Tests
Cryptococcosis

• Indirect fluorescent antibody
• Tube Agglutination
• Latex Agglutination
• (measures antigen)

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Drugs of Choice
Cryptococcosis

• Amphotericin B plus 5-Flucytosine
• OR
• Amphotericin B plus Fluconazole

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The End