Bacterial skin disease: overview

• An uncommon feline dermatosis (except subcutaneous abscessation Abscess which is common!).
• Cause: surface, superficial and deep bacterial infections.
• Signs: pustules, nodules and draining tracts +/- a range of other primary and secondary lesions.
• Diagnosis: microscopic examination of stained smears, bacterial culture and histopathology.
• Treatment: antibiotics; surgical resection of nodules.
• Prognosis: good for surface and superficial infections, poor for some deep infections.

• Surface pyoderma: alopecia, papules and crusts    .
• Superficial pyoderma: alopecia, erosions, ulcers, crusts, occasionally draining tracts and cellulitis  .
• Deep pyoderma: nodules, ulcers, draining tracts, systemic signs.

• Staphylococcus intermedius Staphylococcus intermedius.
• Staphylococcus aureus Staphylococcus aureus.
• Staphylococcus hyicus Staphylococcus spp.
• Pasteurella multocida Pasteurella multocida.
• Streptococcus spp. Streptococcus spp.
• Nocardia spp. Nocardia spp.
• Actinomycoses spp. Actinomyces pyogenes  Actinomyces viscosus.
• Mycobacterium spp. Mycobacterium lepraemurium.
• Escherichia coli  Escherichia coli.
• Pseudomonas spp  Pseudomonas spp.
• Proteus spp.
• Dermatophilus Dermatophilus congolensis.
• Yersinia pestis Yersinia pestis.
• Bacterial L-forms.
• Mycoplasma spp  Mycoplasma and Ureaplasma.

General

• Superficial pyoderma: unclear.

• Surface and deep pyoderma: trauma.

• Unclear.

• Discharging sinuses.
• Pustules.
• Pruritus.
• Alopecia.

• Skin lesions.

• Abscess formation Abscess   .
• Hair loss.

• Lethargy.
• Pyrexia.

Typical lesions

• Nodules.
• Discharging sinuses.
• Ulceration.
• Pustules.
• Papules.
• Crusts.

Typical clinical forms

• Pruritus.
• Lymphadenopathy.
• Alopecia.
• Surface pyoderma .
• Superficial pyoderma   (folliculitis).
• Deep folliculitis and furunculosis  .
• Feline acne   .
• Subcutaneous abscess Abscess   .
• Cellulitis.
• Mycobacterial infections Mycobacterium tuberculosis  Skin: panniculitis due to rapidly growing mycobacteria  Feline leprosy .
• Actinomycosis Actinomyces viscosus  Actinomycosis.
• Nocardiosis Nocardia spp Nocardiosis.
• Feline mycoplasmal Mycoplasma and Ureaplasma and bacterial L form-induced abscesses  L-form bacteria.

Microbiology

• Pathogenic bacteria.

• Microscopy - Diff-Quik or Gram-stained smears of exudate, fine needle aspirate or impression smear Skin: impression smear. Modified Ziehl-Nielsen Stain for acid test bacilli.
• Superficial pyoderma: cellular exudate comprising primarily healthy and degenerative neutrophils with intracellular and extracellular bacteria.

Bacteriology

• See Bacteriology overview Bacteriology.
• If deep pyoderma suspected.
• Culture from biopsy sample or discharge from draining tracts if tissue granules present.
• Special stains Histopathology: special stains required for certain bacteria.

Histopathology

• If deep pyoderma or mycobacterial disease or pseudomycetoma suspected.

Causes of nodules, ulceration and discharging sinus

• Neoplasia Skin: neoplasia.
• Foreign body reaction.
• Immune-mediated skin disease Skin: immunological disease - overview.
• Physical causes.
• Ectoparasites Parasitic skin disease: overview.
• Eosinophilic granuloma complex Eosinophilic granuloma complex.
• Arthropod-bite granuloma.
• Panniculitis.
• Xanthomatosis.
• Sterile nodular granuloma and pyogranuloma.
• Parasitic skin disease Parasitic skin disease: overview.

Causes of pruritus, pustules, papules and crusts

• Flea bite hypersensitivity  Flea bite hypersensitivity.
• Ectoparasites  Parasitic skin disease: overview.
• Dermatophytosis  Dermatophytosis.
• Feline pox virus  Cat pox disease.
• Food hypersensitivity  Food hypersensitivity.
• Atopy  Skin: atopic dermatitis.
• Contact irritant dermatitis  Skin: allergic contact dermatitis.
• Collagenolytic granuloma (linear form).
• FIV  Feline immunodeficiency virus disease, FIP   Feline infectious peritonitis, FeLV   Feline leukemia virus disease.
• Tail-gland seborrhea  Stud tail.
• Cutaneous neoplasia  Hair follicle: neoplasia.
• Immune-mediated skin disease Skin: immunological disease - overview.
• Drug eruption  Drug eruption.
• Solar dermatitis  Dermatitis: solar.
• Contact hypersensitivity  Skin: allergic contact dermatitis.
• Mosquito hypersensitivity.
• Essential fatty acid deficiency Skin: fat responsive dermatosis.
• Hypereosinophilia.
• Malassezia dermatitis Malassezia pachydermatis.
• Lentigo.
• Linear IgA dermatosis.
• Primary keratinization disorders.
• Nutritional disorders Skin: disease - malnutrition.
• Low humidity.

Alopecia

• Other causes of alopecia.

• Topical and systemic antimicrobial therapy Therapeutics: antimicrobial drug  Therapeutics: skin .
• Surgical excision of solitary nodules.

Monitoring

• Subsequent history and clinical findings.

• Surface and superficial pyoderma: good.
• Deep pyoderma: good to poor.

• Concurrent corticosteroid therapy.
• Inappropriate use of antibiotics, eg underdosing - dose +/- duration.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Kennis R A, Wolf A M (1999) Chronic bacterial skin infections in cats. Comp Contin Educ Pract Vet 21 (12), 1108-1115 VetMedResource.
• Ihrke P J (1984) Therapeutic strategies involving antimicrobial treatment of the skin in small animals. J Am Vet Med Assoc 185 (10), 1165-1168 PubMed.
• Thoday K (1981) Skin disease of the cat. Vet Rec 109 (21), 22-35 PubMed.