Nocardia and Actinomyces

Christine L. Terrell

in Mayo Clinic Infectious Diseases Board Review

Published on behalf of © Mayo Foundation for Medical Education and Research

Published in print January 2012 | ISBN: 9780199827626
Published online June 2012 | e-ISBN: 9780199929641 | DOI:

Series: Mayo Clinic Scientific Press

Nocardia and Actinomyces

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Nocardia organisms are filamentous, branching, aerobic organisms that are gram-positive and weakly acid-fast. The main species associated with human disease are Nocardia asteroides, accounting for 80 % to 90 % of cases in the United States and Nocardia brasiliensis, the most common cause of cutaneous and lymphocutaneous disease. Other Nocardia species are also reviewed. Actinomyces organisms are branching, gram-positive, acid-fast–negative, facultative anaerobes. They are fastidious and slow growing, forming sulfur granules in infected tissue, pus, and sinus tract drainage. Similar granules can be seen with N brasiliensis, Actinomadura madurae (with mycetoma), and Staphylococcus aureus (with botryomycosis). Actinomyces odontolyticus does not form sulfur granules. Less common Actinomyces species are also reviewed.

Chapter.  3489 words.  Illustrated.

Subjects: Infectious Diseases

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