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Created page with '*Filamentous, branching actinomycete *Aerobic *Produces motile zoospores *No growth on Sabouraud dextrose agar *Dermatophilosis most prevalent in tropical and subtropical region…'
*Filamentous, branching actinomycete
*Aerobic
*Produces motile zoospores
*No growth on Sabouraud dextrose agar
*Dermatophilosis most prevalent in tropical and subtropical regions
*Organisms found in scabs and in foci in skin of carrier animals
*Dormant zoospores become activated when moisture and temperature levels are favourable
*Zoospores may survive 3 years in scabs
*'''Pathogenicity''':
**Does not usually invade healthy skin
**Entrance after trauma or persistent wetting
**Activated zoospores produce germ tubes which develop into filaments which invade the epidermis
**Invasion causes an accute inflammatory response with many [[Neutrophils - WikiBlood|neutrophils]]
**Microabscesses are formed in the skin
**Raised crusts develop in the affected regions
*[[Bacterial skin infections - Pathology#Dermatophilosis|'''Pathology''']]
*'''Diagnosis''':
**Giemsa-stained smears from scabs reveal branching filaments containing zoospores
**Immunofluorescence
**Scab material can be cultured on blood agar at 37 degrees centigrade, 2.5-10% carbon dioxide for 5 days
**Zoospores can be cultured
**After incubation, colonies are yellow and haemolytic (after 48 hours); they later become rough and yellow, and gain a mucoid appearance
**No growth on Sabouraud dectrose agar
*'''Clinical infections''':
**Infection usually confined to epidermis
**Dermatophilosis
**Disease most prevalent in young animals
**Damage to the skin predisposes to infection; blood-sucking insects also thought to be involved in transmission
**Lesions after heavy rainfall predominantly affect dorsum of farm animals
**Papules, serous, exudative matting of hair, raised crusty scabs
**Scab formation more prominent in sheep and cattle than in horses
**Lesions may resolve within weeks if dry weather, or may progress
*'''Treatment''':
**Parenteral antibiotics e.g oxytetracycline, pr penicillin-streptomycin combinations

[[Category:Actinomycetes]]
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