Candida spp, Cryptococcus spp, Malassezia spp, Trichosporon spp

Question 1

Diagnosis of Candida albicans

Answer 1

Yeasts, reproduce by budding

1) Culture :stains (+) with gram stain , Smooth, creamy white glistering colonies
2) microscopy tissue sample : staining with GMS & PAS
3) for invasive Candidiasis —> mannan/antimannan antigen detecting test + β-D-glucagon assay
2) Identification of hyphae or pseudohyphae with KOH

Question 2

what is used for the identification of Hyphae or pseudohyphae?

Answer 2

KOH

Question 3

Transmission of Candida Albicans

Answer 3

Colonization of GI tract, from mouth to rectum. Also, vagina & urethra, on skin & under nails and toenails
–> part of mouth flora

Question 4

VF/patho of candida albicans

Answer 4

forms biofilms
–> Capability to switch from yeast to hyphae in vivo – infected organs, hyphal stage predominates

Question 5

Defence mechanisms against Candida spp?

Answer 5

1) Primary defence mechanism is intact skin & mucosal surfaces
2) PNFs, key against Candida,
3) Th17 cells are important in mucosal defence against Candida

Question 6

Clinical Manifestaions of Candida spp?

Answer 6

1) Thrush
–> Oral Candida infections, creamy white patches on tongue & oral mucosa, easily removed
leaving painful, bleeding, ulcerative surface
2) Candida esophagitis
3) Vaginitis
4) Balanitis (STD)
5) Candidemia –> 3rd-5th most common cause of CLABSI
6) UTIs –> Cystitis, pyelonephritis (Does not need therapy-only if symptoms are present)

Question 7

Who is at risk of Candidemia casued by candida spp?

Answer 7

1) neutropenia
2) haematologic malignancies
3) GI surgery,
4) premature infants,
5) parenteral nutrition

Question 8

Diagnosis/VF of Cryptococcous Neoformans

Answer 8

Encapsulated yeast-like fungi, in soil, esp. if enriched with “pigeon droppings”

Test: Differentiation from other yeasts:
1. Indian ink in CSF: stains the capsule
2. Culture : Urease(+) test (Cryptococcus possess urease unlike Candida spp)
3. Positive laccase activity
4. CrAg(Cryptococcal Antigen) –> invasive disesae

Question 9

Transmission of Cryptococcus spp?

Answer 9

1) Inhalation through environment, dissemination from lungs, usually to CNS
2) Traumatic inoculation into skin , although less frequently

Question 10

Clinical manifesations of Cryptococcus spp

Answer 10

2 most common sites of infections are: lung & CNS

1) Lungs –> nodules, with or w/o hilar lymphadenopathy that may resemble malignancy
2) CNS –> Subacute (Fungal) meningitis

Question 11

Complications of Trichosporon spp

Answer 11

1) catheter-associated fungemia in neutropenic patients
2) most common cause of non-candidal yeast infection in patients with hematologic malignancies