Difference between revisions of "Bacterial skin infections - Pathology"

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#REDIRECT[[:Category:Integumentary System - Bacterial Infections]]
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Cutaneous bacterial infections tend to be called '''pyodermas'''. They are superficial, deep and are common in dogs, but less common in other species.
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===[[Deep pyoderma]]===
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*Less common than superficial pyoderma
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*Occurs mainly in dogs
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*Affects infundibulum, isthmic portion of hair follicles and surrounding dermis and subcutis
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*Heals with scarring
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*Local lymph nodes are often affected
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*Often secondary to immunosuppression, follicular hyperkeratosis or [[Parasitic skin infections - Pathology#Demodicosis|demodicosis]]
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*May also be a sequele to [[Bacterial skin infections - Pathology#Superficial pyoderma|superficial pyoderma]]
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*Grossly:
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**[[Skin Glossary - Pathology|Crusted papules, pustules, alopecia, abscesses, nodules, fistulas, ulcers, haemorrhagic bullae]]
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**In dogs may look similar to [[Pyotraumatic Dermatitis|pyotraumatic dermatitis]]
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*Microscopically:
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**Pyogranulomatous folliculitis and furunculosis
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**Nodular or diffuse dermatitis
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**Panniculitis
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*May involve a foreign bodey reaction to follicular contents and draining sinuses develop
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*If chronic, scarring and loss of adnexa
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*Bacteria often isolated include [[:Category:Staphylococcus species|''Staphylococcus'' spp.]], especially ''S. intermedius'' in dogs, [[:Category:Streptococcus species|''Streptococcus'' spp.]], ''[[Corynebacterium pseudotuberculosis]]'', [[:Category:Pseudomonas and Burkholderia species|''Pseudomonas'']], [[:Category:Pasteurella and Mannheimia species|''Pasteurella'']], [[Proteus|''Proteus'']], [[Escherichia coli|''E.coli'']]
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====[[Staphylococcal Folliculitis and Furunculosis]]====
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====[[Subcutaneous Abscesses]]====
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*Purulent exudate within dermis and subcutis
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*Commonly occurs in cats due to contamination of penetrating wounds
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*Surrounding wall of collagen and fibroblasts may develop
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*Common bacteria (often normal mouth flora)
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**[[Pasteurella multocida|''Pasteurella multocida'']], [[Fusobacterium necrophorum|''Fusobacterium'' spp.]], [[:Category:Streptococcus species|beta - haemolytic streptococci]], [[Bacteroides|''Bacteroides'']]
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[[Category:Integumentary System - Bacterial Infections]]
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====[[Bacterial Granulomatous Dermatitis]]====
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*Usually due to saprophytes
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*Grossly:
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**Diffuse or nodular lesions
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**May ulcerate and form drainage fistulas
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*Microscopically:
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**Macrophages +/- multinucleated giant cells
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**[[Necrosis - Pathology#Caseation Necrosis|Caseous necrosis]] and [[Neutrophils|neutrophils]]
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*'''Mycobacterial granulomatous or pyogranulomatous lesions'''
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**Usually caused by ''[[Mycobacterium lepraemurium]]'' (feline leprosy) or other ''Mycobacteria''
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**Most commonly lesions appear on head, neck and legs
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*'''[[Botryomycosis]]'''
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[[Category:Integumentary System - Bacterial Infections]]
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===[[Bacterial Pododermatitis]]===
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*Digital infections in ruminants
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*'''[[Contagious Footrot]]'''
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*'''[[Necrobacillosis]]''' of the foot
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[[Category:Integumentary System - Bacterial Infections]]
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===[[Systemic Bacterial Infections]]===
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*[[Salmonella|'''Salmonellosis''']]
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**Capillary dilatation and congestion -> cyanosis of external ears and abdoman
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**Thrombosis -> necrosis of extremities
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*'''Erysipelas''' in pigs
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**Caused by [[Erysipelothrix rhusiopathiae|''Erysipelothrix rhusiopathiae'']]
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**Vasculitis, thrombosis, ischaemia -> cutaneous lesions - firm, raises, rhomboidal pink to dark purple areas
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*[[Clostridium novyi|''Clostridium novyi'']]
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**Severe cellulitis, toxaemia and death of young rams during breeding season (due to traumatised heads) - 'big head'
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*[[Streptococcus equi subsp. equi|''Streptococcus equi'']]
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**In horses
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**Immune complex vasculitis -> [[Haemorrhage#Purpura haemorrhagica|purpura]]
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[[Category:Integumentary System - Bacterial Infections]]
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[[Category:Integumentary System - Pathology]]

Revision as of 19:08, 21 February 2011


Cutaneous bacterial infections tend to be called pyodermas. They are superficial, deep and are common in dogs, but less common in other species.




Deep pyoderma

Staphylococcal Folliculitis and Furunculosis

Subcutaneous Abscesses


Bacterial Granulomatous Dermatitis

  • Usually due to saprophytes
  • Grossly:
    • Diffuse or nodular lesions
    • May ulcerate and form drainage fistulas
  • Microscopically:
  • Mycobacterial granulomatous or pyogranulomatous lesions
    • Usually caused by Mycobacterium lepraemurium (feline leprosy) or other Mycobacteria
    • Most commonly lesions appear on head, neck and legs
  • Botryomycosis

Bacterial Pododermatitis


Systemic Bacterial Infections

  • Salmonellosis
    • Capillary dilatation and congestion -> cyanosis of external ears and abdoman
    • Thrombosis -> necrosis of extremities
  • Erysipelas in pigs
    • Caused by Erysipelothrix rhusiopathiae
    • Vasculitis, thrombosis, ischaemia -> cutaneous lesions - firm, raises, rhomboidal pink to dark purple areas
  • Clostridium novyi
    • Severe cellulitis, toxaemia and death of young rams during breeding season (due to traumatised heads) - 'big head'
  • Streptococcus equi
    • In horses
    • Immune complex vasculitis -> purpura
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