Actinomycosis is a slowly progressive suppurative infection characterized
by fistula formation. A number of gram positive, non spore forming bacteria
from the genus Actinomyces are the etiologic agents.1-3 It
is encountered worldwide in three main clinical forms: cervicofacial,
thoracic, and abdominal.1 Metastatic lesions to
other sites are also reported. With appropriate therapy, most patients
with cervicofacial or abdominal infection recover completely.
Actinomyces species are part of the normal flora
of the human gastrointestinal tract. They do not inhabit the female
genitourinary tract in the absence of an intrauterine device (IUD).4 Actinomycosis
is not considered an opportunistic or communicable disease. Although
uncommon in children, actinomycosis has been reported in infancy.5 The
disease is not related to occupation, season, or race.
A. israelii, the species that most commonly produces
human disease, is part of normal oral flora. A. viscosus, A.
naeslundii, A. odontolyticus, A.
meyeri, and Propionibacterium (Arachnia) propionica are
also established etiologic agents.1-3 Cervicofacial
and abdominal infections are thought to occur when these organisms are
traumatically introduced into tissues.6 Predisposing
factors for actinomycosis include gingivitis, gingival trauma, dental
procedures, tooth-related infections, diabetes mellitus, malnutrition,
immunosuppression, and local tissue damage from different causes
including trauma, radiation, and neoplasia as well as the use of
an IUD.7,8 It has been shown than Actinomyces sp
require the presence of other bacteria to multiply. Thus, actinomycosis
is frequently polymicrobial in nature, and concomitant bacterial
species such as Eikenella corrodens, Actinobacillus
actinomycetemcomitans, Fusobacterium, Capnocytophaga, Staphylococcus,
microaerophilic streptococci, and Enterobacteriaceae are
often isolated from actinomycotic lesions.9-11Actinomyces sp
require an anaerobic or microaerophilic environment for growth and
demonstrate gram positive branching filaments, often appearing
as beaded filaments.
A pivotal step in pathogenesis is the disruption of mucosal barriers,
allowing access of these organisms to deep tissue. Thus, oral and cervicofacial
disease are associated with dental procedures, trauma, and oral
surgery.7 However, actinomycotic infections are
infrequent, and some cases of actinomycosis may even develop after
minor trauma such as eruption of a normal tooth.7 In
fact, actinomycosis may not develop after major oral trauma or surgery.
This indicates that oral or mucosal trauma alone is not the only
factor responsible for actinomycotic infections. Other conditions may
be required for Actinomyces sp to proliferate and
establish an infection. These include the duration and severity
of trauma that induce the microaerophilic environment as well as
the synergistic effect of other bacteria.12 Abdominal
infection is preceded by gastrointestinal surgery, appendicitis,
diverticulitis, traumatic injury secondary to gunshot or knife wounds, or
foreign bodies such as fish bones.11 Pelvic actinomycosis
is associated with intrauterine devices.8 Pulmonary
disease is believed to be secondary to aspiration.1 Once
inoculated, the organism replicates and spreads contiguously in
a slow and progressive manner with little respect for tissue planes.