A Study of the Isolation, Cultivation and Pathogenicity of Actinomyces Israeli Recovered from the Human Mouth and from Actinomycosis in Man

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Abstract
15 strains of A. israeli, the microorganism known to be the principal agent of actinomycosis, were isolated and studied, 4 from cervico-facial actinomycosis and 11 from gingival 1808 scrapings taken under oral pathological conditions in the absence of actinomycosis. Four additional strains were isolated, 3 from salivary calculus and one from gingival scrapings, and identified but not maintained; and one other strain, not isolated by the authors, was included in some of the tests. A method has been described which facilitated isolation of the organism, particularly from contaminated sources, based on its growth and distinctive appearance on streaked plates of Bacto brain heart infusion agar. The characteristics of the organism in these cultures are described. Expts. on O2 tolerance of the cultures have indicated that the most nearly optimal conditions for continued growth among those tried are provided by anaerobiosis in the presence of 5% CO2. Some strains, however, were found capable of limited growth in air; and considerable variation was observed in O2 tolerance both from strain to strain and for a given strain at different times. Pure cultures have been maintained without difficulty by cultivation under anaerobic conditions with CO2 and by alternate transfer through different culture media. Repeated inoculation by different routes of pure cultures of 9 strains of A. Israeli, in 24 guinea pigs and 16 rabbits, resulted negatively in most instances. However, clear evidence of exptl. actinomycosis was obtained in 5 animals, progressive and fatal in 2 guinea pigs and 1 rabbit, localized and benign in 2 other rabbits. Repeated intraven. or intraperit. injn. of large doses of organisms seemed to be innocuous, while single or repeated subcut. injn. usually produced only mild local lesions from which the organism could seldom be reisolated. Fatal reactions were obtained irregularly by intrapleural injn. and by inclusion in the inoculum of sterile pulverized salivary calculus. Intracut. injns. of living or killed cultures in 5 previously inoculated and 2 uninoculated rabbits gave no clear evidence that allergy is associated with progressive infection. The results as a whole are in accord with the view that actinomycosis is an endogenous infection, but indicate that essential factors in the pathogenesis of the disease are still unknown.

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