Felis ISSN 2398-2950

Nocardia spp

Contributor(s): Rosanna Marsella

Introduction

Classification

Taxonomy

  • Genus: Nocardia.
  • Family: Nocardiaceae.
  • Order: Actinomycetales.

Etymology

  • Named after Edmond Nocard, a French veterinarian.

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Clinical Effects

Epidemiology

Habitat

  • Thrive in the environment.
  • Saprophytes found in many climates in soil and water.
  • May exist as indigenous flora or contaminants.

Lifecycle

  • Actively growing filaments alternate with resting coccobacillary "spores".

Transmission

  • Inhalation - pulmonary disease.
  • Soil contamination of wounds.

Pathological effects

  • Antibody-mediated and cell-mediated immune responses, often develop during nocardial infections.
  • Severe infection may occur in immunosuppressed animals, particularly of cell-mediated immunity.
  • Disease does not usually occur unless there are a large number of organisms and some immunosuppression in the host to which it is exposed.
  • Prevent phagolysosome production and therefore survive within phagocytic vacuoles of the host cells. Due to cell wall lipids, similar to Mycobacterium spp.
  • Characteristic granulomas result.
  • Exudates may contain soft granules of bacteria and neutrophils but NOT the sulfur granules typical of Actinomyces spp.
  • Nocardia asteroides is responsible for various granulomatous infections and abscess formation in a wide range of animals, most commonly localized granulomatous abscesses and pyothorax in the thoracic cavity in dogs and cats, and chronic granulomatous mastitis in cattle. Grains (bacterial colonies) may be seen macroscopically in the exudate and histologically on biopsies.
  • Nocardia farcinata causes farcy in cattle in tropical countries.
  • Nocardia brasiliensis and Nocardia otidis-caviarum mainly cause infections in man.

Other Host Effects

  • Essentially saprophytic.

Control

Control via chemotherapies

  • Limited range of effective antimicrobial agents.
  • Trimethoprim-sulfamethoxazole Trimethoprim and erythromycin Erythromycin possibly the most effective.

Other countermeasures

  • Drainage of pus.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Bonenberger T E, Ihrke P J, Naydan D K & Affolter V K (2001) Rapid identification of tissue micro-organisms in skin biopsy specimens from domestic animals using polyclonal BCG antibody. Vet Dermatol 12(1), 41-47.
  • Conville P S, Fischer S H, Cartwright C P & Witebsky F G (2000) Identification of nocardia species by restriction endonuclease analysis of an amplified portion of the 16S rRNA gene. J Clin Microb 38(1), 158-164.
  • Laurent F J et al (1999) Rapid identification of clinically relevant Nocardia species to genus level by 16S rRNA gene PCR. J Clin Microbiol 37(1), 99-102.
  • Workman M R et al (1998) Identification and antibiotic susceptibility of Nocardia farcinica and N. nova in the UK. J Med Microbiol 47(1), 85-90.

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