Difference between revisions of "Bacterial skin infections - Pathology"

Revision as of 19:05, 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.

Superficial Pyoderma

Superficial pyoderma in a dog (Courtesy of Bristol BioMed Image Archive)

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:
- Crusted papules, pustules, alopecia, abscesses, nodules, fistulas, ulcers, haemorrhagic bullae
- In dogs may look similar to 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 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)
- Pasteurella multocida, Fusobacterium spp., beta - haemolytic streptococci, Bacteroides

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

@@ Line 1: / Line 1: @@
-#REDIRECT[[:Category:Integumentary System - Bacterial Infections]]
+<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]]====
+[[Category:Integumentary System - Bacterial Infections]]
+===[[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 [[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 necrophorum|''Fusobacterium'' spp.]], [[:Category:Streptococcus species|beta - haemolytic streptococci]], [[Bacteroides|''Bacteroides'']]
+[[Category:Integumentary System - Bacterial Infections]]
+====[[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]]'''
+[[Category:Integumentary System - Bacterial Infections]]
+===[[Bacterial Pododermatitis]]===
+*Digital infections in ruminants
+*'''[[Contagious Footrot]]'''
+*'''[[Necrobacillosis]]''' of the foot
+[[Category:Integumentary System - Bacterial Infections]]
+===[[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#Purpura haemorrhagica|purpura]]
+[[Category:Integumentary System - Bacterial Infections]]
+[[Category:Integumentary System - Pathology]]