288
M. A. GERENCSER
1975; Slack and Gerencser, 1970a, 1975; Bowden and Hardie, 1973). At
present, five species are included in the genus Actinomyces. Of these, A.
israelii is the principal agent of human actinomycosis, but A . naeslundii, A .
viscosus and A . odontolyticus are also found in human infections (Georg,
1974; Slack and Gerencser, 1975; Mitchell et al., 1977). A . bovis, the type
species of the genus and the agent of bovine actinomycosis, has never been
demonstrated in or isolated from human materials. The numerous reports
of A. bovis in human actinomycosis found in the literature are due to the
practice of lumping all Actinomyces under the single species name bovis.
I n addition to A . bovis, A. israelii and A. viscosus have been found in
animal infections (Georg, 1974; Georg et al., 1972). I n addition to causing
classical actinomycosis, species of the genus Actinomyces are thought to be
involved in periodontal disease and in some types of dental caries (Slack
and Gerencser, 1975).
Arachnia propimica will be included in this discussion because it causes
clinically typical actinomycosis and must be differentiated from A. israelii.
This organism, originally described as Actinomyces propionicus, was
reclassified because it differs significantly in carbohydrate metabolism and
cell wall composition from Actinomyces.
In the past ten years considerable progress has been made in the classification of the family Actinomycetaceae and the genus Actinomyces. The
classification of the family as it appears in the eighth edition of “Bergey’s
Manual of Determinative Bacteriology’’ (1974) is shown in Table I. This
classification differs from that of the seventh edition of the Manual in that
the genus Nocardia has been removed from the family and the genera
Arachnia, Bzj?dobacterium, Bacterionema and Rothia have been added. In
the genus Actinomyces, one species, A . baudetii, was deleted and placed on
the list of nomina dubia while A. naeslundii, A . odontolyticus and A . viscosus
were added. Modification of the description of the genus to include catalase
positive organisms permitted the reclassification of Odontomyces viscosus as
Actinomyces viscosus. Three species are listed in the Manual as of uncertain
affiliation. Of these, A . eriksonii should be placed in the genus Bifdobacterium while the status of A . humiferus and A. suis is still uncertain.
It is already evident that further modifications of the classification
shown in Table I will be needed. All recent evidence seems to support the
earlier suggestions that A . naeslundii and A . viscosus are varieties of a single
species. For the purposes of this discussion, the classification will be used
in its present form and A . naeslundii (catalase negative) and A. viscosus
(catalase positive) will be considered separate species. The status of A . suis
needs to be clarified as does that of A . humij-erus, a soil organism. An
additional species, Actinomyces meyerii, has been recognized since the
publication of Bergey’s Manual. Strains of the organism classified as
M. A. GERENCSER
1975; Slack and Gerencser, 1970a, 1975; Bowden and Hardie, 1973). At
present, five species are included in the genus Actinomyces. Of these, A.
israelii is the principal agent of human actinomycosis, but A . naeslundii, A .
viscosus and A . odontolyticus are also found in human infections (Georg,
1974; Slack and Gerencser, 1975; Mitchell et al., 1977). A . bovis, the type
species of the genus and the agent of bovine actinomycosis, has never been
demonstrated in or isolated from human materials. The numerous reports
of A. bovis in human actinomycosis found in the literature are due to the
practice of lumping all Actinomyces under the single species name bovis.
I n addition to A . bovis, A. israelii and A. viscosus have been found in
animal infections (Georg, 1974; Georg et al., 1972). I n addition to causing
classical actinomycosis, species of the genus Actinomyces are thought to be
involved in periodontal disease and in some types of dental caries (Slack
and Gerencser, 1975).
Arachnia propimica will be included in this discussion because it causes
clinically typical actinomycosis and must be differentiated from A. israelii.
This organism, originally described as Actinomyces propionicus, was
reclassified because it differs significantly in carbohydrate metabolism and
cell wall composition from Actinomyces.
In the past ten years considerable progress has been made in the classification of the family Actinomycetaceae and the genus Actinomyces. The
classification of the family as it appears in the eighth edition of “Bergey’s
Manual of Determinative Bacteriology’’ (1974) is shown in Table I. This
classification differs from that of the seventh edition of the Manual in that
the genus Nocardia has been removed from the family and the genera
Arachnia, Bzj?dobacterium, Bacterionema and Rothia have been added. In
the genus Actinomyces, one species, A . baudetii, was deleted and placed on
the list of nomina dubia while A. naeslundii, A . odontolyticus and A . viscosus
were added. Modification of the description of the genus to include catalase
positive organisms permitted the reclassification of Odontomyces viscosus as
Actinomyces viscosus. Three species are listed in the Manual as of uncertain
affiliation. Of these, A . eriksonii should be placed in the genus Bifdobacterium while the status of A . humiferus and A. suis is still uncertain.
It is already evident that further modifications of the classification
shown in Table I will be needed. All recent evidence seems to support the
earlier suggestions that A . naeslundii and A . viscosus are varieties of a single
species. For the purposes of this discussion, the classification will be used
in its present form and A . naeslundii (catalase negative) and A. viscosus
(catalase positive) will be considered separate species. The status of A . suis
needs to be clarified as does that of A . humij-erus, a soil organism. An
additional species, Actinomyces meyerii, has been recognized since the
publication of Bergey’s Manual. Strains of the organism classified as