Difference between revisions of "Bacterial skin infections - Pathology"
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− | # | + | {{review}} |
+ | |||
+ | {{toplink | ||
+ | |backcolour = FFCCCC | ||
+ | |linkpage =Integumentary System - Pathology | ||
+ | |linktext =Integumentary System | ||
+ | |maplink = Integumentary System (Content Map) - Pathology | ||
+ | |pagetype =Pathology | ||
+ | |sublink1 = Skin Infectious - Pathology | ||
+ | |subtext1 = SKIN INFECTIOUS | ||
+ | }} | ||
+ | <br> | ||
+ | Cutaneous bacterial infections tend to be called '''pyodermas'''. They are superficial, deep and are common in dogs, but less common in other species. | ||
+ | ===Superficial pyoderma=== | ||
+ | [[Image: Superficial pyoderma dog.jpg|100px|thumb|right|<small><center>Superficial pyoderma in a dog (Courtesy of Bristol BioMed Image Archive)</center></small>]] | ||
+ | *Affects epidermis and upper infundibulum of hair follicles | ||
+ | *No scarring when healed | ||
+ | *Grossly: | ||
+ | **Erythema | ||
+ | **Alopecia | ||
+ | **[[Skin Glossary - Pathology|Papules and pustules]] | ||
+ | **[[Skin Glossary - Pathology|Crusts]] | ||
+ | **[[Skin Glossary - Pathology|Epidermal collarettes]] | ||
+ | *Microscopically: | ||
+ | **Intraepidermal pustular dermatitis | ||
+ | **Superficial suppurative folliculitis | ||
+ | **Bacteria commonly not seen | ||
+ | ===[[Impetigo]]=== | ||
+ | |||
+ | |||
+ | ====[[Dermatophilosis]]==== | ||
+ | |||
+ | |||
+ | ====[[Greasy pig disease]]==== | ||
+ | |||
+ | ====[[Ovine Fleece Rot]]==== | ||
+ | |||
+ | ====[[Equine Pastern Folliculitis]]==== | ||
+ | |||
+ | ===Deep pyoderma=== | ||
+ | |||
+ | *Less common than superficial pyoderma | ||
+ | *Occurs mainly in dogs | ||
+ | *Affects infundibulum, isthmic portion of hair follicles and surrounding dermis and subcutis | ||
+ | *Heals with scarring | ||
+ | *Local lymph nodes are often affected | ||
+ | *Often secondary to immunosuppression, follicular hyperkeratosis or [[Parasitic skin infections - Pathology#Demodicosis|demodicosis]] | ||
+ | *May also be a sequele to [[Bacterial skin infections - Pathology#Superficial pyoderma|superficial pyoderma]] | ||
+ | *Grossly: | ||
+ | **[[Skin Glossary - Pathology|Crusted papules, pustules, alopecia, abscesses, nodules, fistulas, ulcers, haemorrhagic bullae]] | ||
+ | **In dogs may look similar to [[Skin Environmental - Pathology#Pyotraumatic dermatitis|pyotraumatic dermatitis]] | ||
+ | *Microscopically: | ||
+ | **Pyogranulomatous folliculitis and furunculosis | ||
+ | **Nodular or diffuse dermatitis | ||
+ | **Panniculitis | ||
+ | *May involve a foreign bodey reaction to follicular contents and draining sinuses develop | ||
+ | *If chronic, scarring and loss of adnexa | ||
+ | *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'']] | ||
+ | |||
+ | ====[[Staphylococcal Folliculitis and Furunculosis]]==== | ||
+ | |||
+ | ====Subcutaneous abscesses==== | ||
+ | |||
+ | *Purulent exudate within dermis and subcutis | ||
+ | *Commonly occurs in cats due to contamination of penetrating wounds | ||
+ | *Surrounding wall of collagen and fibroblasts may develop | ||
+ | *Common bacteria (often normal mouth flora) | ||
+ | **[[Pasteurella multocida|''Pasteurella multocida'']], [[Fusobacterium|''Fusobacterium'' spp.]], [[:Category:Streptococcus species|beta - haemolytic streptococci]], [[Bacteroides|''Bacteroides'']] | ||
+ | |||
+ | ====Bacterial granulomatous dermatitis==== | ||
+ | |||
+ | *Usually due to saprophytes | ||
+ | *Grossly: | ||
+ | **Diffuse or nodular lesions | ||
+ | **May ulcerate and form drainage fistulas | ||
+ | *Microscopically: | ||
+ | **Macrophages +/- multinucleated giant cells | ||
+ | **[[Necrosis - Pathology#Caseation Necrosis|Caseous necrosis]] and [[Neutrophils|neutrophils]] | ||
+ | *'''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=== | ||
+ | |||
+ | *Digital infections in ruminants | ||
+ | *'''[[Contagious Footrot]]''' | ||
+ | |||
+ | *'''[[Necrobacillosis]]''' of the foot | ||
+ | |||
+ | ===Systemic bacterial infections=== | ||
+ | |||
+ | *[[Salmonella|'''Salmonellosis''']] | ||
+ | **Capillary dilatation and congestion -> cyanosis of external ears and abdoman | ||
+ | **Thrombosis -> necrosis of extremities | ||
+ | *'''Erysipelas''' in pigs | ||
+ | **Caused by [[Erysipelothrix rhusiopathiae|''Erysipelothrix rhusiopathiae'']] | ||
+ | **Vasculitis, thrombosis, ischaemia -> cutaneous lesions - firm, raises, rhomboidal pink to dark purple areas | ||
+ | *[[Clostridium novyi|''Clostridium novyi'']] | ||
+ | **Severe cellulitis, toxaemia and death of young rams during breeding season (due to traumatised heads) - 'big head' | ||
+ | *[[Streptococcus equi subsp. equi|''Streptococcus equi'']] | ||
+ | **In horses | ||
+ | **Immune complex vasculitis -> [[Haemorrhage - Pathology#Purpura haemorrhagica|purpura]] |
Revision as of 11:18, 30 June 2010
This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing. |
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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.
Superficial pyoderma
- Affects epidermis and upper infundibulum of hair follicles
- No scarring when healed
- Grossly:
- Erythema
- Alopecia
- Papules and pustules
- Crusts
- Epidermal collarettes
- Microscopically:
- Intraepidermal pustular dermatitis
- Superficial suppurative folliculitis
- Bacteria commonly not seen
Impetigo
Dermatophilosis
Greasy pig disease
Ovine Fleece Rot
Equine Pastern Folliculitis
Deep pyoderma
- Less common than superficial pyoderma
- Occurs mainly in dogs
- Affects infundibulum, isthmic portion of hair follicles and surrounding dermis and subcutis
- Heals with scarring
- Local lymph nodes are often affected
- Often secondary to immunosuppression, follicular hyperkeratosis or demodicosis
- May also be a sequele to superficial pyoderma
- Grossly:
- Microscopically:
- Pyogranulomatous folliculitis and furunculosis
- Nodular or diffuse dermatitis
- Panniculitis
- May involve a foreign bodey reaction to follicular contents and draining sinuses develop
- If chronic, scarring and loss of adnexa
- Bacteria often isolated include Staphylococcus spp., especially S. intermedius in dogs, Streptococcus spp., Corynebacterium pseudotuberculosis, Pseudomonas, Pasteurella, Proteus, E.coli
Staphylococcal Folliculitis and Furunculosis
Subcutaneous abscesses
- Purulent exudate within dermis and subcutis
- Commonly occurs in cats due to contamination of penetrating wounds
- Surrounding wall of collagen and fibroblasts may develop
- Common bacteria (often normal mouth flora)
Bacterial granulomatous dermatitis
- Usually due to saprophytes
- Grossly:
- Diffuse or nodular lesions
- May ulcerate and form drainage fistulas
- Microscopically:
- Macrophages +/- multinucleated giant cells
- Caseous necrosis and neutrophils
- 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
- Digital infections in ruminants
- Contagious Footrot
- Necrobacillosis of the foot
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