Furthermore, actinomycosis is generally a polymicrobial infection, with isolates numbering as many as 5-10 bacterial species. Establishment of human infection may require the presence of such companion bacteria, which participate in the production of infection by elaborating a toxin or enzyme or by inhibiting host defenses. These companion bacteria appear to act as copathogens that enhance the relatively low invasiveness of actinomycetes. Specifically, they may be responsible for the early manifestations of actinomycosis and for treatment failures.
Once infection is established, the host mounts an intense inflammatory response (ie, suppurative, granulomatous), and fibrosis may then follow. Infection typically spreads contiguously, frequently ignoring tissue planes and invading surrounding tissues or organs. Ultimately, the infection produces draining sinus tracts. Hematogenous dissemination to distant organs may occur in any stage of actinomycosis, whereas lymphatic dissemination is unusual.
Cervicofacial actinomycosis is the most common type of the infection, comprising 50-70% of reported cases. This infection typically occurs following oral surgery or in patients with poor dental hygiene. Cervicofacial actinomycosis is characterized in the initial stages by soft-tissue swelling of the perimandibular area. Direct spread into the adjacent tissues occurs over time, along with development of fistulas (sinus tracts) that discharge purulent material containing granules with a yellow sulfurlike appearance (termed sulfur granules). Invasion of the cranium or the bloodstream may occur if the disease is left untreated.
Thoracic actinomycosis accounts for 15-20% of cases. Aspiration of oropharyngeal secretions containing actinomycetes is the usual mechanism of infection. Occasionally, thoracic actinomycosis results from the introduction of organisms via esophageal perforation, by direct spread from an actinomycotic process of the neck or abdomen, or via hematogenous spread from a distant lesion. Thoracic actinomycosis commonly presents as a pulmonary infiltrate or mass, which, if left untreated, can spread to involve the pleura, pericardium, and chest wall, ultimately leading to the formation of sinuses that discharge sulfur granules.
Actinomycosis of the abdomen and pelvis accounts for 10-20% of reported cases. Typically, these patients have a history of recent or remote bowel surgery (eg, perforated acute appendicitis, perforated colonic diverticulitis following trauma to the abdomen) or ingestion of foreign bodies (eg, chicken or fish bones), during which actinomycetes are introduced into the deep tissues. The ileocecal region is involved most frequently, and the disease typically presents as a slowly growing tumor. Diagnosis is usually established postoperatively, following exploratory laparotomy for a suspected malignancy. Involvement of any abdominal organ, including the abdominal wall, can occur by direct spread, with eventual formation of draining sinuses. Pelvic actinomycosis most commonly ascends from the uterus in association with intrauterine contraceptive devices (IUCDs). In such cases, an IUCD has been in place for an average of 8 years.
Actinomycosis is rare. During the 1970s, the reported annual incidence of actinomycosis in the Cleveland area was 1 case per 300,000 persons. Improved dental hygiene and widespread use of antibiotics for various infections have probably contributed to the declining incidence of this disease.
Because of the bacteria's normal location in the nose and throat, actinomycosis most commonly affects the face and neck. The infection can sometimes occur in the chest (pulmonary actinomycosis), abdomen, pelvis, or other areas of the body. The infection is not contagious. This means it does not spread to other people.
Treatment of actinomycosis usually requires antibiotics for several months to a year. Surgical drainage or removal of the affected area (lesion) may be needed. If the condition is related to an IUD, the device must be removed.
Russo TA. Agents of actinomycosis. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 254.
Actinomyces are gram-positive filamentous non-acid fast anaerobic to microaerophilic bacteria that typically colonize the human mouth, urogenital tract, and gastrointestinal tract but can cause an infection known as actinomycosis. The infection is usually granulomatous, suppurative, and may involve multiple sulfur-containing abscesses that form sinus tracts. Actinomycosis is generally not diagnosed until the chronic phase. In otherwise healthy individuals, the infection is generally treatable with a prolonged course of intravenous antibiotics; the outcome is more nebulous for immunocompromised individuals. This activity reviews the evaluation and treatment of actinomycosis and highlights the role of the interprofessional team in caring for patients with this condition.
Objectives:Explain why actinomycosis is generally not diagnosed until it reaches the chronic stage.Identify the most common sites for actinomycosis infection and the expected signs and symptoms associated with each site.Describe the treatment considerations for actinomycosis.Explain why a well-integrated, interprofessional team approach is needed to provide optimal care to patients with actinomycosis. Access free multiple choice questions on this topic.
Thoracic actinomycosis may occur in patients with alcohol use disorder and seizure disorders. Pulmonary infection usually occurs as a complication of aspiration. Rarely disease can result from a human bite. Infection in the cervical and facial areas typically occurs following oral cavity surgery in patients with poor oral hygiene. Pelvic actinomycosis has been associated with the use of intrauterine devices (IUDs). Abdominal actinomycosis has been reported after any abdominal surgery but is most commonly seen after an appendectomy.
The imaging for actinomycosis is nonspecific. In the acute presentation, it can look like any other pneumonia. In chronic forms, it can present as a pulmonary mass or can cavitate. In the case of a mass malignancy, actinomycosis is an important diagnosis to consider. Especially when it cavitates, tuberculosis is an important differential diagnosis to consider. The computed tomography scan findings can vary depending upon the duration of illness and can include consolidation, cavitation, pleural effusion, lymph node enlargement, atelectasis, and ground glass opacification.
Imaging of actinomycosis can be nonspecific; findings will depend upon the site of infection and chronicity. In chronic cases, a CT scan might show an enterocutaneous fistula with multiple abdominal abscesses. The best test is a culture of the infected site.
A CT scan can show pelvic mass (6 to 7 cm) with the cystic lesion. Lymphadenopathy can be seen in 40% to 60% of cases. A tubo-ovarian abscess is highly suggestive of infection with actinomycosis. Bladder actinomycosis can present like bladder carcinoma, with bladder thickening and hematuria.
Complications of actinomycosis include the development of abscesses and the spread of the infection. Osteomyelitis is a possible complication with the involvement of the ribs, vertebrae, and the mandible. Nervous system involvement will include meningitis, brain abscess, actinomycetoma, cranial, epidural and subdural infection, and spinal epidural infection.
Good oral hygiene and limitation of alcohol may limit cervicofacial, pulmonary, and central nervous system (CNS) actinomycosis. In women, changing the IUD device every five years prevents actinomycosis infection.
Actinomycosis infections are not common, but when they do occur, they are usually serious. The organism can infect almost any organ; thus, actinomycosis is best managed by an interprofessional team that includes an infectious disease consult, intensivist, general surgeon, endocrinologist, an internist, and a specialty trained infectious disease pharmacist. These patients need close monitoring by nurses because the infection can rapidly prove fatal in immunocompromised hosts or patients with diabetes. Pharmacists should assist with the coordination of antibacterial treatment and help the team avoid drug-drug interactions, monitor for drug therapy complications, and assist in educating the patient and family on medication compliance. The outcomes depend on the site of infection, its severity, patient immune status, and other comorbidities. In healthy people, the infection has low morbidity and mortality if treated.
At early stages of the disease, a focal pulmonary consolidation occurs, which can be surrounded by pulmonary nodules, but there are often no associated physical symptoms at this stage. This primary pulmonary involvement could secondly lead to constitution of a peripheral mass, with or without cavitation, which could invade adjacent tissue.36,37 At this stage, pulmonary actinomycosis is usually characterized by fibrotic lesion with slow contiguous growth passing through the anatomical barriers.24 The mass is often confused with malignancy.
Bronchial actinomycosis is rare. It may occur after disruption of the mucosal barrier, especially in patients with endobronchial stent, or with a bronchial foreign body aspiration (for example, of a fish bone).3,37,38
The gold standard for diagnosing pulmonary actinomycosis is histological examination and bacterial culture of a lung biopsy, obtained by percutaneous biopsy guided by CT scan or by open surgical resection.3,25
Contrast-enhanced magnetic resonance images showing contiguous spread of pulmonary actinomycosis to the spine (case 2), with thoracic spondylitis of the T3 vertebral body, associated with anterior paravertebral abscess (arrow) (A). Magnetic resonance image showing back soft tissue infiltration, with posterior epiduritis and infection of L2 and L4 vertebral bodies (arrows) in a paraplegic patient with plurimicrobial bone and joint infection following chronic back scar (case 6) (B). 041b061a72