Introduction

Classification

Taxonomy

• Order: Actinomycetales.
• Family: Actinomycetaceae.
• Genus: Arcanobacterium.
• Species: pyogenes.

Etymology

• Gk: pyogenes- pus-producing.

Active Forms

Clinical Effects

Epidemiology

Habitat

• Colonizes the mucous membranes and skin of susceptible species.

Lifecycle

• Reproduces on the mucous membranes and skin of the host by binary fission.
• Does not reproduce using spores.

Transmission

• Endogenous infection.
• Bites.

Pathological effects

• Killed by phagocytes.
• Man: cell-mediated and humoral immunity - circulating antibody, produced during infection does not confer protection.
• Specific resistance, if any, is probably cell-mediated.

• Trauma or infection by another agent → stimulates latent infection → active infection (Actinomycosis) → pyogranulomatous reaction (bacterial colonies with suppuration) → surrounding granulation, mononuclear infiltration and fibrosis.

Cattle, sheep and pigs

• Suppurative mastitis (acute and chronic).
• Suppurative pneumonia.
• Septic arthritis.
• Endometritis.
• Umbilical infections.
• Wound infections.
• Mixed infections with Fusobacterium necrophorum and other anaerobic bacteria.

Bulls and boars

• Seminal vesiculitis.

Cattle alone

• Summer mastitis (mixed infection with an anaerobe, eg Peptostreptococcus indolicus).
• Vegetative endocarditis.

Other Host Effects

• Present on host's mucous membranes - mouth or oropharynx, secondarily gastrointestinal tract.

Control

Control via chemotherapies

• Penicillin G Benzylpenicillin , tetracycline Tetracycline.
  Response to treatment in summer mastitis is disappointing, presumably due to involvement of other bacteria.

Vaccination

• None.

Other countermeasures

• If possible, establish drainage of affected site.

Vaccination

• None.

Other countermeasures

• If possible, establish drainage of affected site.

Diagnosis

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Kirpensteijn J & Fingland R B (1992) Cutaneous actinomycosis and nocardiosis in dogs: 48 cases (1980-1990). JAVMA 201 (6), 917-920 PubMed.
• Edwards D F, Nyland T G, Weigel J P (1988) Thoracic, abdominal, and vertebral actinomycosis. Diagnosis and long-term therapy in three dogs. JVIM 2 (4), 184-191 PubMed.
• Hardie E M & Barsanti J A (1982) Treatment of canine actinomycosis. JAVMA 180 (5), 537-541 PubMed.