27 plus species including:
- Nocardia amarae
- Nocardia asteroides
- Nocardia brevicatena
- Nocardia brasiliensis
- Nocardia carnea
- Nocardia farcinica
- Nocardia otitidiscaviarum
- Nocardia transvalensis
- Nocardia vaccinii
|Gram Stain:||Positive to variable, usually partially acid-fast.|
|Morphology:||Rudimentary to extensively branched vegetative hyphae which fragment in situ or on mechanical disruption into bacteroid, rod-shaped to coccoid elements. Short to long chains of conidia occasionally found on hyphae and substrate hyphae.|
|Size:||0.5-1.2 micrometers in diameter.|
|Spores:||No endospores, sporangia, sclerotia, or synnemata are formed.|
|Other:||Aerial hyphae are almost always produced.|
Colonies have a chalky, mat or velvety appearance. Color may appear brown, tan, pink, orange, red, purple, gray, or white. Texture may be smooth or granular, irregular, wrinkled, or heaped.
Aerobic and mesophilic. Chemoorganotrophic, having an oxidative type metabolism.
KEY BIOCHEMICAL REACTIONS
Widely distributed in soil, water, air, sewage, insects and plants, may be present in clinical specimens as opportunistic pathogens.
Nocardia are usually pathogenic opportunists in humans and animals whose host defenses are compromised. One notable exception is N. brasiliensis which is typically considered an obligatory pathogen.
The basic types of human diseases caused are (a) pulmonary disease, neural and/or systemic nocardiosis (b) actinomycotic mycetomas which are tumor-like growths of the organisms within the tissues; and (c) localized cutaneous or subcutaneous infections which usually represent primary infections.
|For culture:||Lowenstein Jensen Medium.|
|For selective isolation:||Columbia Blood Agar or Sabouraud Dextrose Agar.|
|For maintenance:||Yeast Extract Glucose Agar for short-term maintenance and lyophilization for long-term preservation.|
|Temperature:||35 degrees C.|
|Time:||3-10 days (look for pigmented colonies with downy aerial hyphae).|
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2. Holt, J.G., et al. 1986. Bergey's Manual of Systemic Bacteriology , Vol. I & II. Williams & Wilkins, Baltimore, MD.
3. The Oxoid Vade-Mecum of Microbiology . 1993. Unipath Ltd., Basingstoke, UK.
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5. Internet: www.hardlink.com /Bacterial Database Search, February, 1998.
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7. Koneman, et al. 1997. Color Atlas and Textbook of Diagnostic Microbiology , 5th ed. Lippincott, Philadelphia, PA.