Yeasts

What are considered true yeasts?

Those who reproducing sexually by forming ascospores or basidiospores

What are considered yeastlike fungi?

Isolates that are not capable of sexual reproduction

What is the primary sp that causes yeast infection?

Candida albicans

What are characteristics of Candida albicans?

• Thrush

• An indicator of immunosuppression

• Can evolve into serious infection in patients receiving long-term antibiotics

What are the characteristic of Candida glabrata?

• May account for 21% of all urinary yeast isolates

• Tend to be aggressive and difficult to treat w/ traditional antifungal therapy

Which sp is this? On what plate?

C. albicans on chrome agar

Which sp is this?

C. dubliniensis

How can you tell the difference between Candida albicans vs Canadia dubliniensis?

Candida dubliniensis does NOT grow at 42C while Candia albicans CAN grow at 42C

What are the other notable species of Candida?

• Candida krusei

• Candida tropicalis

• Candida parapsilosis

Why is Candida auris a concering species?

• Emerging multidrug-resistant yeast linked to high mortality rates

• Hospital setting, likely transmitted patient to patient

What is the pathology of Cryptococcus?

Opportunistic infection

• Meningitis, pneumonia and septicemia

What are the characteristics of Cryptococcus?

Mucoid due to capsule

• India ink test —> Results in clear halos around organism

Blastocondia only

Which sp is this? Which test is being done on this slide?

Cryptococcus; India Ink

What are the characteristics of Rhodotorula?

• noted for its bright salmon-pink color

• Capsulated and urea-positive

• Some species are nitrate-positive

What are characteristics of Trichosporon?

• Causes invasive localized and disseminated disease

• Some sp causes white piedra

What are the colony characteristics of Trichosporon?

At first cream-colored, most and soft —> As it aged, it becomes wrinkled, powdery and crumb-like

What is the microscope morphology of trichosporon sp?

• True and pseudohyphae formation

• Blastocondia singly or in chains

• Arthoconidia on older cultures

Which sp is this?

Trichosproron sp (Colony)

Which sp is this?

Trichosporon sp (Micro)

What is P. jirovecii?

• Formerly considered a protozoa but now its considered a Pneumocystis fungi

• Non-filamentous fungus

What is the life cycle of Pneumocystis?

1) Trophozoite —> Multiply via binary fission

2) Precyst

3) Cyst —> Infective stage

How would you diagnose Pneumocystis?

1) Biopsy and aspirates of the lung via Giemsa and Grocott’s methenamine silver (GMS)

2) Calcofluor white —> Blue-white color when stained and viewed under ultraviolet (UV) light

Which sp is this? Which stain is it in?

Pneumocystis Cysts in silver stain

Which sp is this? Which stain is it in?

Pneumocystis in Giemsa stain

What are some clinical disease cause by yeasts / yeast-like fungi?

• Candidiasis

• White piedra

• Pityriasis

• Crypotococcosis

• Onychomycosis

• Vulvovaginal

• UTI

How much is required for blood specimen?

8-10 mL of whole blood

How much is required for Bone Marrow?

0.5 mL

• Pediatric blood culture bottle or inoculate media bedside

How much is required for Cerebrospinal Fluid (CSF)?

2 mL

• Inoculate directly to media; centrifuge and make smears from sediment

How much is required for Sputum?

3-5 mL

• Must split specimen before decontamination for AFB testing

How much is required for Sterile Body Fluids?

10-50mL

• Heparin may be used to prevent clotting

How much is required for Tissues?

Place in sterile gauze wetted with sterile saline

• Must be grounded / minced prior to media inoculation

How much is required for Urine?

10-40 mL (Use early morning for concentration)