Tinctorial and Morphologic Properties Distinguishing Actinomycosis and Nocardiosis

Actinomycosis and nocardiosis in visceral infections are distinguished usually on the basis that Actinomyces israelii is not acid fast, but is associated with sulfur granules, whereas Nocardia asteroides is often acid fast, and may be associated with sulfur granules. Because of a case of cultureproved actinomycosis, in which sulfur granules and acid-fast organisms were found, the reliability of these criteria was examined. Materials from four cases of actinomycosis and one culture of A. israelii were stained with the classic Ziehl -Neelsen acid-fast method and with the Putt modification. Every specimen was acid fast with the Putt, but not with the Ziehl-Neelsen method. This suggests that both A. israelii and N. asteroides may be acid fast under certain conditions and may be indistinguishable by these stains. Review of the English literature on nocardiosis showed sulfur granules reported only in infections of skin and not in viscera. Thus, the presence of the granules in viscera suggests actinomycosis.