Skin: bacterial skin disease – overview

• Common secondary dermatosis.
• Cause: unclear.
• Signs: pustules with or without range of primary and secondary lesions, +/- pruritus.
• Diagnosis: history, clinical signs. histopathology, bacteriology, microscopy.
• Treatment: antimicrobial therapy.
• Prognosis: depends on type of bacterial infection.

• Primary and secondary lesions ranging from papules, pustules and vesicles to crust formation, scaling, epidermal collarettes, hyperpigmentation and ulceration.

• Pustules are the hallmark of pyoderma, but easily rupture so rarely seen.

• Hypersensitivity Skin: atopy.
• Ectoparasites Skin: parasitic disease - overview.
• Endocrine/metabolic disease Skin: hyposomatotropism.
• Long-term glucocorticoids.

• Immune incompetency, eg neoplasia.
• Poor nutrition.
• Unhygenic environment.
• Anatomical factors, eg facial, lip, tail, vulvar and body folds.
• Environmental factors, eg high temperature and humidity.
• External trauma.

• Viral infection.
• Idiopathic keratinization defects.

Specific

• Staphylococcus intermedius Staphylococcus intermedius.

• Staphylococcus aureus Staphylococcus aureus.
• Staphylococcus epidermidis Staphylococcus epidermidis.
• Streptococcus spp. Streptococcus spp.
• Pseudomonas spp. Pseudomonas.
• Proteus spp. Proteus spp.
• Nocardia Nocardia spp.
• Dermatophilus.
• Mycobacterium spp. Mycobacterium tuberculosis Skin: canine leproid granuloma syndrome.
• Escherichia coli Escherichia coli.

• Unclear.
• Host factor +/- predisposing factor (?affecting anatomical and physiological epidermal barrier function) → penetration ofStaphylococcus intermedius Staphylococcus intermedius and its toxins into the skin → bacterial multiplication → exceed a threshold → pyoderma.

• Pustules.
• Pruritus.

• Skin lesions which may be localized or generalized.
• Pruritus.

• Lethargy.
• Pyrexia.
• Depression.

• Pustules .
• Papules .
• Crusts .
• Scaling .
• Pruritus.
• Multifocal alopecia Skin: alopecia - overview.
• Epidermal collarettes.
• Hyperpigmentation .

• Juvenile pyoderma Juvenile cellulitis.
• Folliculitis .
• Superficial pustular pyoderma .
• Vulvar-fold pyoderma .
• Skin-fold pyoderma .
• Callus pyoderma .
• Furunculosis .
• Interdigital furunculosis .
• Pyoderma .
• Granulomatous dermatitis, secondary to pyoderma .
• Bacterial paronychia .

• Coagulase-positivestaphylococciespeciallyStaphylococcus intermedius Staphylococcus intermedius.

• Diff-Quik or Gram-stained smears of purulent exudate.
• Cellular exudate comprising primarily healthy and degenerative neutrophils with intracellular and extracellular cocci.
• May be difficult to find cocci in older lesions.

• Culture of pustule contents if:
  • No response to antibiosis +/- recurrence of lesion.
  • +/- Atypical clinical lesions.
  • +/- Large numbers of rods found on microscopy.
  • +/- Deep pyoderma.
• Coagulase-positivestaphylococciespeciallyStaphylococcus intermedius- commonly isolated.

• Examination of skin biopsy essential for deep pyoderma.

• Impetigo Skin: impetigo.
• Folliculitis Skin: bacterial folliculitis.

• Hypersensitivity.
• Ectoparasitic infection Skin: parasitic disease - overview.
• Malasseziadermatitis Skin: malassezia disease :
• Dermatophytosis Skin: dermatophytosis.

• Endocrine skin disease Skin: hyposomatotropism.
• Metabolic skin disease.
• Neoplasia.
• Immune-mediated skin disease.
• Drug eruption.
• Demodicosis Skin: demodectic mange.
• Physical causes.

• Contact irritant dermatitis Skin: allergic contact dermatitis.
• Sub-corneal pustular dermatosis.
• Sterile eosinophilic pustular dermatitis Skin: eosinophilic folliculitis and furunculosis.
• Linear IgA dermatosis Skin: linear IgA syndrome.
• Bullous impetigo Skin: impetigo.
• Candidiasis Skin: candidiasis.
• Toxic epidermal necrolysis Skin: toxic epidermal necrolysis.
• Erythema multiforme Skin: erythema multiforme.
• Pemphigus complex.

• Topical and systemic antimicrobial therapy Therapeutics: antimicrobial drug.
• Treat until 7-10 days after clinical resolution.

Monitoring

• Subsequent history and clinical findings.

• Depends on specific disease.

• Predisposing factors not identified and resolved.
• Concurrent corticosteroid therapy - poorly responsive to steroid therapy, bacterial infection should be suspected if skin disease.
• Inappropriate use of shampoo, eg insufficient contact time.
• Inappropriate use of antibiotics, eg penicillin, ampicillin, underdosing, too short duration.
• Inappropriate use of antibiotics that are inactivated by penicillinase, eg ampicillin, amoxicillin, penicillin.
• Inadequate duration of treatment.
• Underdosing of antibiotics.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Littlewood J D, Lakhani K H, Paterson S, Wood J L N & Chanter N (1999) Clindamycin hydrochloride and clavulanate-amoxycillin in the treatment of canine superficial pyoderma. Vet Rec 144 (24), 662-665 PubMed.
• Mason I S (1993) Selection and use of antibacterial agents in canine pyoderma. In Practice 15 (3), 129-34 VetMedResource.
• Mason I S (1991) Canine pyoderma. JSAP 32 (8), 381-6 VetMedResource.
• DeBoer D J (1990) Strategies for management of recurrent pyoderma in dogs. Vet Clin N A 20 (6), 1509-24 PubMed.
• Ihrke P J (1987) An overview of bacterial skin disease in the dog. British Vet J 143 (2), 112-8 PubMed.

Other sources of information

• Morrelo K A & Mason I S (1995)Handbook of Small Animal Dermatology.Pergamon Press. pp 127-136, 287-294 (Excellent problem-oriented approaches and diagnostic plans).
• Muller G Het al(1995)Muller and Kirk's Small Animal Dermatology.5th edition. Philadelphia: W B Saunders. pp 280-328 (Detailed dermatology text book for in-depth reading).
• Griffin C E, Kwochka K W & MacDonald J M (1993)Current Veterinary Dermatology - The Science and Art of Therapy.St Louis: Mosby Year Book. pp 3-21 (Well presented dermatology text book).
• Grant D I (1991)Skin diseases in the Dog and Cat.2nd edn. Oxford: Blackwell Scientific Publications. pp 8-27 (Concise for quick reference).
• Locke P H, Harvey R G & Mason I S (1993) (eds) Mason I S & Kwochka K W. In:Manual of Small Animal Dermatology.BSAVA. pp 60-64, 213-232 (Excellent differential diagnosis including frequency of occurrence indicators).