. Actinomycosis

Actinomycosis


 

Nahed Abdel-Haq and Ashir Kumar


 

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 etio-logic agents.1-3 It is encountered worldwide in three main clinical forms: cervicofacial, thoracic, and abdominal.1


ImageETIOLOGIC AGENT AND PATHOGENESIS


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 etio-logic 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.


ImageCLINICAL MANIFESTATIONS


Actinomycosis may present either as a chronic indolent process or as an acute rapidly progressive infection; the clinical manifestations may vary between these two extremes. However, the most common presentation remains the chronic indolent form.12 Cervicofacial disease, accounting for 60% of patients with actinomycosis, presents as a slowly progressive, indurated swelling or mass, usually at the angle of the jaw, but it can occur anywhere on the cheek, mandible, or anterior neck.7 The duration of illness is typically several months. Pain is seldom prominent. A low-grade fever may occur in as many as 50% of patients. Trismus is uncommon.13


The clinical progression may be marked by episodes of suppuration that are contained by reactive fibrosis. Although the lesions may be intermittently fluctuant and appear as a cold abscess, they will eventually progress to a hard mass with lumpy appearance.7 The disease spreads to adjacent tissues without regard to anatomical structures. Lymphadenopathy is uncommon.13 The skin overlying the mass may become violaceous, and sinus tract formation with spontaneous discharge often occurs. Most patients do not appear systematically ill. Image


Cervicofacial actinomycosis presents as a chronic mass lesion or recurrent abscess in the head and neck region. Maxillary and ethmoid sinusitis may also occur.15 Another presentation is with recurrent episodes of otitis media that transiently respond to antibiotics (conventional short-course therapy) and by resistance to myringotomy.16 Fatal extension into the mastoid and central nervous system also occurs.16,17 Central nervous system involvement has been documented in 2% to 10% of cases of cervicofacial actinomycosis, being due to either direct extension from soft tissues through the cranial foramen, or hematogenous spread.17-20 Spread to the meninges may cause meningitis, meningoencephalitis, and brain abscess. Other forms of CNS involvement include tumorlike lesions called actinomycetomas as well as subdural and epidural abscesses.20


Thoracic involvement accounts for about 15% of patients with actinomycosis. It results from inhalation of contaminated aerosol particles or aspiration of contaminated secretions from the oropharynx or the upper gastrointestinal tract.21 However, it may also arise from a perforating gastrointestinal ulcer or after the intestinal mucosa is penetrated by a sharp object such as a knife, ingested bone, or bullet.11 Abdominal actinomycosis may also follow gastric bypass surgery.30 Poor oral hygiene is a pre-disposing condition. Immunocompromised patients are at increased risk.23 Thoracic actinomycosis is rare in children and young adults. Most cases are due to A. israelii.23 The most common presentation is a slowly progressive disease involving the parenchyma and pleura.24 As the disease progresses, the lung becomes consolidated and an abscess may form; the pleura and thoracic wall are invaded and produce empyema, rib involvement, subcutaneous abscesses, or draining sinuses.25 Hemoptysis has been reported.26 Delayed diagnosis may result in bacteremic dissemination with increased mortality rates.27 Pulmonary actinomycosis must be differentiated from nocardiosis, tuberculosis, fungal infections, and cancer.


Abdominal actinomycosis accounts for 20% of patients.1 The majority of cases begin in the ileocecal region as a complication of appendicitis or appendectomy (65% of cases).29 Abdominal infections are polymicrobial; gram-negative bacilli are frequent concomitant pathogens.11 The initial symptoms are insidious and include abdominal discomfort, fever, weight loss, change in bowel habits, and malaise. Abdominal tenderness and guarding in the right iliac fossa are common with perforated appendix.31 Months to years may pass from the time of the inciting event to clinical recognition of this indolent infection. During the initial stage of infection, an abscess forms that is followed by extension to the peritoneum. The abscess consists of pus surrounded by a thick layer of granulation tissue. Abdominal examination often reveals a mass. In advanced stages, the disease progresses to fistula formation, both internally and externally, simulating inflammatory bowel disease.32 Abscess rupture through the abdominal wall produces a typical draining sinus from which sulfur granules are detected.32 Colonic involvement accounts for approximately 15% of abdominal actinomycosis, presenting with obstruction or fistula.35 Hepatic infection occurs in 5% of cases of abdominal actinomycosis, usually by direct extension. Most cases are unilobar.42Image


Pelvic actinomycosis is commonly associated with the presence of any type of intrauterine contraceptive device (IUD) and appears to occur rarely unless the IUD has been in place for at least 2 years.50 It has been reported months after removal of an IUD, making a history of prior use important.51Actinomyces sp have been identified in 8% to 20% of women using IUD. Although most of those colonized individuals are asymptomatic, up to 25% developed symptoms of pelvic infection.52,53 Presentation is most frequently that of an indolent infection, with fever, weight loss, abnormal vaginal bleeding, and pain being common. Image


ImageDIAGNOSIS


The diagnosis of actinomycosis is obvious when a draining sinus in the neck, chest, or abdomen produces sulfur granules.14,32 The presence of Actinomyces-like organisms on Papanicolaou-stained cervical specimens associated with pain, abnormal bleeding, or discharge, is an indication for removal of an IUD and a 14-day course of penicillin or tetracycline.56 However, the presence of Actinomyces sp on cervical smear in an asymptomatic woman does not require IUD removal or antibiotic therapy.58


Imaging studies such as computed tomography and magnetic resonance imaging will show the actinomycosis lesions as ill-defined, infiltrative, soft tissue masses extending to surrounding spaces without regard to anatomic facial planes.36 Regional lymphadenopathy is uncommon; this finding may be helpful to differentiate actinomycosis from carcinoma.6 The diagnosis of pelvic actinomycosis can be established on clinical grounds or following microbiological identification from material obtained by needle aspiration or surgical drainage. The Actinomyces sp may also be demonstrated in cervical smears and endome-trial biopsies.57 Microscopic examination of these granules reveals gram-positive beaded filaments that are not acid-fast. Biopsies for culture and histopathologic evaluation are frequently needed for diagnosis of actinomycosis. Pathologic examination will reveal a central suppurative area surrounded by chronic granulation tissue, and a thick fibrous capsule. Image


Actinomyces sp are easily grown below the surface in thioglycollate medium, provided the inoculum does not contain other organisms. Growth usually appears within 5 to 7 days but may take up to 2 to 4 weeks.14 Because these organisms are normal flora of the oral cavity and female genital tract, isolation of the organisms is not sufficient for diagnosis in the absence of sulfur granules. In addition to culture, the use of immunofluorescent-conjugated monoclonal antibodies (IFAs) has improved identification of Actinomyces species. Image


ImageTREATMENT


Prolonged and intensive penicillin therapy and surgery remain the mainstay of treatment of most cases of actinomycocsis.1 Initially, intravenous aqueous penicillin should be given for 2 to 6 weeks Image depending on the extent of the disease and response to therapy. Subsequently, patients should receive oral penicillin V or amoxicillin, for 6 to 12 months. Patients allergic to penicillin may be treated with erythromycin, clindamycin, chloramphenicol, or tetracycline (minocycline).77 Accessible abscesses should be incised and drained. Because extensive fibrosis may limit antibiotic penetration of the abscess, surgical excision should be considered for refractory fibrotic lesions that respond slowly to antibiotic therapy. Persistent sinus tracts should be marsupialized. Surgical management should always be accompanied by effective antibiotic therapy.11,55


REFERENCES


See references on DVD.


Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Jan 7, 2017 | Posted by in PEDIATRICS | Comments Off on . Actinomycosis

Full access? Get Clinical Tree

Get Clinical Tree app for offline access