9- Clinical and pathological changes seen in fungal infections and diagnosis

Question 1

Name the 3 major tissue reactions seen with fungal infections

Answer 1

Acute suppurative inflammation & micro-abscess formation

Chronic inflammation - pyogranulomatous/granulomatous

Necrosis

Question 2

Name a presentation of superficial mycoses

Answer 2

Alopecia, claw disease, papule, pustules
Erythema, scale, lichenification

Question 3

T/F Systemic mycoses cause granulomas and necrosis in organs which are affected

Answer 3

True

Question 4

Name a common soil saprophyte

Answer 4

Aspergillosis (Aspergillus spp)

Question 5

List 3 diagnostic tests used for fungi

Answer 5

Direct microscopic examination & cytology

Fungal culture

Histopathology

Woods lamp (dermatophytosis)

Question 6

What is the main clinical effect of fungal disease?

Answer 6

Tissue mycosis - tissue invasion

Question 7

Describe how fungal infections can cause necrosis

Answer 7

occurs if fungi invade blood vessels
causes infarction (lack of blood supply)
therefore tissue death

Question 8

Describe how fungal infections can lead to chronic inflammation

Answer 8

when fungi phagocytosed, their walls not fully degraded
when phagocytes die this fungal material is released into tissues
macrophages recruited
they produce chemokines and cytokines which recruits more macrophages (this keeps getting repeated- causing a granulomatous inflammatory response)

Question 9

List 3 superficial mycoses

Answer 9

Dermatophytosis
Malassezia
Candida infection

Question 10

Describe a candida infection

Answer 10

are very rare in small animals
affects skin mucosae
ulcers/ erosions covered with tenacious yellow/grey exudate

Question 11

Why do most subcutaneous (deep) mycoses generally occur

Answer 11

traumatic implantation of fungus- mostly on feet/ limbs or head

Question 12

List the ways in which Aspergillus spp generally infects

Answer 12

inhalation
local inoculation
haematogenous spread

Question 13

Describe how you would diagnose dermatophytes

Answer 13

fungal culture of hair, dry skin scrapings/ scale, coat brushings

Question 14

How do you generally speciate fungi

Answer 14

asexual spore type
colony appearance
features of vegetative hyphae

Question 15

For which fungal infections is histopathology generally used

Answer 15

subcut/ systemic infections