Clinically Significant Fungi

Question 1

Candida auris

Answer 1

Yeast linked to climate change that colonizes skin.
Resistant to all major antifungal drugs & has caused outbreaks in over 20 countries.
Opportunistic pathogen → affects elderly & patients with: diabetes, immunosuppression, surgery history, or those on broad-spectrum antibiotics.

Question 2

Candida auris – Specimen Collection

Answer 2

Adult patients: swabs from nose, throat, & perineum.
Children: swabs from nose, throat, & groin.
Samples collected in Amies transport medium & sent in a clear bag.

Question 3

Candida auris – Laboratory Diagnosis

Answer 3

Microscopy: gram-positive oval yeast cells.
Germ tube test negative (unlike C. albicans).
Culture: on SDA & CHROMagar Candida Plus → appears light blue with a blue halo.
MALDI-TOF mass spectrometry for identification.

Question 4

Candida auris – Treatment

Answer 4

Echinocandin.
If treatment fails, liposomal amphotericin B can be used.

Question 5

Aspergillus fumigatus

Answer 5

A mould found in environment, with >200 species of Aspergilli.
Typically inhaled & becomes pathogenic in immunocompromised individuals (e.g., cystic fibrosis, transplant patients).

Question 6

Pulmonary Aspergillosis – Clinical Syndromes

Answer 6

Allergic bronchopulmonary aspergillosis: allergic reaction to Aspergillus antigen within lungs.
Treatment: corticosteroids & antifungals.

Aspergilloma: fungal ball in pulmonary cavity.
Treatment: long-term voriconazole, possibly surgery.

Question 7

Aspergillus – Specimen and Diagnosis

Answer 7

Specimens: sputum or bronchoalveolar lavage, collected before treatment.
Microscopy: calcofluor white & KOH wet mounts show septate hyphae.
Culture: SDA plates at 30°C, 37°C, & 45°C; rapid growth in 48 hours; white, yellow, brown or green colonies.
CT scan imaging → shows fungal ball.

Question 8

Ringworm

Answer 8

A superficial infection caused by dermatophytes like Trichophyton, Microsporum, & Epidermophyton.
Appears as an itchy, scaly, ring-like rash with central clearing.
Common among young adults & spreads through environmental contact or shared facilities.

Question 9

Ringworm – Types

Answer 9

Tinea Capitis: scalp infection, common in children, may cause hair loss.
Tinea Corporis: affects body excluding specific areas (scalp, face, hands, feet, or groin).
Tinea Pedis: athlete’s foot.

Question 10

Ringworm – Specimen and Diagnosis

Answer 10

Samples: skin scrapings from edge of ringworm lesion & nail clippings - collected in black paper.

Microscopy:
○KOH wet mount shows branched septate hyphae.
○Lactophenol blue wet mount shows macro/microconidia of T. rubrum.

Culture:
○T. rubrum: White, cotton fluffy surface top & red, brown to yellow reverse.
○M. canis: White fluffy surface with yellow perimeter at top & deep yellow reverse.

Question 11

Ringworm – Treatment

Answer 11

Topical antifungals: Clotrimazole 1% cream.
Oral antifungals used for extensive or resistant infections.