What is Actinomycosis?
Actinomycosis is a somewhat rare infection that can play out slowly over time. It’s caused by a type of bacteria called Actinomyces, which is not very resistant to acid and does not require much oxygen to survive. This infection creates lumps and pus-filled areas inside the body, and if it becomes chronic or long-term, it can lead to multiple abscesses that form connecting tunnels in the body, with little lumps referred to as sulfur granules. About 70% of these infections can be traced back to two specific types of Actinomyces bacteria: Actinomyces israelii or Actinomyces gerencseriae.
Diagnosing actinomycosis can be quite challenging, as it requires the bacteria to be isolated and grown in specific conditions with limited oxygen over a long period. Additionally, the infection often involves a mix of different bacteria and very infrequently spreads through the bloodstream. Other bacteria typically found together with Actinomyces in these infections include Aggregatibacter actinomycetemcomitans, Prevotella, Streptococcus, Enterobacteriaceae, Peptostreptococcus, and Staphylococcus.
The bacteria causing actinomycosis can cause an infection by inhibiting the body’s defense mechanisms and/or reducing the level of oxygen present.
What Causes Actinomycosis?
Actinomyces is a type of bacteria that naturally lives in our mouth, genitals, and digestive tract. Since it’s a normal part of these areas, it can be tough to distinguish between just having the bacteria and having an infection.
Thoracic actinomycosis, a specific type of this infection, can happen in people who abuse alcohol or have seizures. This lung infection usually comes about as a complication from inhaling substances like food or vomit into the lungs. It’s rare, but it can also result from a human bite. Infections in the neck and face usually happen after surgery in the mouth, particularly in people who don’t maintain good oral hygiene.
Pelvic actinomycosis has been linked to the use of intrauterine devices (IUDs) – a type of birth control. Abdominal actinomycosis, on the other hand, has been reported after surgery in the abdominal area. It is most commonly seen after removal of the appendix.
Risk Factors and Frequency for Actinomycosis
The disease tends to affect men between the ages of 20 and 60 more frequently, particularly those in their 40s and 50s. For every three men who get sick, one woman gets the disease. The use of intrauterine devices (IUDs) for contraception has led to an increase in the number of women getting sick. It is also observed more often in areas where people generally have lower income. It’s important to note that people from all racial and ethnic groups can get the disease.
Signs and Symptoms of Actinomycosis
The symptoms of a particular infection can vary depending on where the infection is located in the body. A full health history, including potential risk factors, is crucial in diagnosing these conditions.
The most common infection location is in the tissues surrounding the upper and lower jaw, constituting about 60% of all cases. Symptoms include a growing, pain-free lump that becomes hard, possible red or blue skin discoloration, and eventually abscesses containing yellow sulfur granules may form. Patients might have a history of an oral procedure or injury. Other symptoms can include trouble with chewing food and stiffness of the jaw, especially in long-standing infections. Swollen lymph nodes are not typically associated with this infection.
For genitourinary infections, there’s often a history of intrauterine device (IUD) use. The symptoms can be similar to gynecological tumors, both cancerous and non-cancerous. Symptoms might include lower abdominal pain, constipation, and vaginal discharge. Fever rarely occurs unless the infection spreads to the peritoneum.
- Infections in the stomach or bowels (GI) may have a history of abdominal surgery or swallowing a fish bone. Depending on the area of infection, symptoms may vary, including difficulties swallowing, low-grade fever, weight loss, tiredness, nausea, vomiting, changes in bowel habits, and abdominal pain with or without a palpable mass.
- In the rare case where the liver and bile tract are involved, there may be right-upper abdomen pain and jaundice (a yellowing of the skin and eyes).
- Last, lung infections may develop over an extended period, and by the time they’re diagnosed, they’re often in the chronic phase. Early symptoms might include mild fever and weight loss. These infections can look like other chronic lung diseases or cancers. Common symptoms are a chronic cough that may produce mucus, possible blood in the mucus, shortness of breath, and chest pain. Sometimes, cavities form in the lung tissue, which is a hallmark of these infections. If the infection spread widely and the person’s immune system is weakened, severe low oxygen levels and acute respiratory distress syndrome (ARDS) can occur, which is a severe form of lung injury.
Testing for Actinomycosis
When investigating the possibility of an infection, doctors may start by drawing blood to check your white blood cell levels. An increase in these cells, a condition called leukocytosis, along with raised levels of inflammatory markers such as C-reactive protein and erythrocyte sedimentation rate, often indicates an underlying infection. However, these tests, along with serological tests (i.e. testing blood serum), aren’t specific to any particular infection and thus cannot solely confirm the diagnosis.
To accurately identify an infection, doctors opt for a biopsy culture test, which involves sampling tissue from the infected area. Rather than swabbing the infected sites, samples are sent to a lab to be cultured and analyzed for the presence of bacteria. Despite this, sometimes cultures can yield false-negative results. In these cases, a preliminary diagnosis can be made by searching under a microscope for certain telltale signs such as rod-shaped bacteria and sulfur granules.
The picture given by the imaging results may depend on the location of the infection and may look similar to other chronic infections like tuberculosis, or even cancer. Here’s how it breaks down for different parts of the body:
In the head and neck area, imaging won’t specifically pinpoint the disease but can help figure out the extent of soft tissue and bone damage. Dental x-rays can be useful in spotting root abscesses. CT and MRI scans might spot bone loss related to chronic infection.
For lung infections, the disease can vary in appearance drastically. For instance, an acute infection may present like any common pneumonia while a chronic one could show up on a scan as a mass, potentially with cavities forming within it. A CT scanner might reveal a range of findings such as inflammation, cavitation (formation of cavities), fluid buildup around the lungs, enlarged lymph nodes, collapse of lung areas, and hazy lung fields. Despite these findings, a biopsy obtained with bronchoscopy; CT-guided methods; or through video-assisted minimally invasive surgery by a chest surgeon is the gold standard for diagnosis. Culturing pleural fluid doesn’t usually yield the organism. Same for sputum culture, unless the patient has cavitary disease.
In the gastrointestinal tract, imaging may show an abnormal connection between the skin and intestines (enterocutaneous fistula) and multiple abscesses in the abdomen in chronic cases. Confirmatory diagnosis is usually made by culturing a sample from the infected site.
In the genitourinary system, a CT scan may reveal pelvic mass along with cystic lesions and swollen lymph nodes. Especially for women, an abscess in the fallopian tubes and ovaries is a particularly strong sign of infection. If there’s suspicion of infection in the bladder, it can show up as bladder thickening and blood in urine, mimicking bladder cancer. In these cases, fluid samples might be taken after removing an intrauterine device (IUD) or a tissue sample may be required to rule out cancer.
Treatment Options for Actinomycosis
Most cases of this condition can be treated using antibiotics, and sometimes, surgery may be used as an additional treatment. Often, the following antibiotics are prescribed:
- Penicillin G
- Long-lasting beta-lactam antibiotics followed by oral amoxicillin
- Cephalosporin
If you’re allergic to penicillin, there are alternative medications available including:
- Clindamycin
- Macrolides (like erythromycin, clarithromycin, or azithromycin)
- Doxycycline
For infections caused by multiple types of bacteria, a combination of metronidazole and a beta-lactamase inhibitor might be used. There’s no need for antimicrobial susceptibility testing because the antibiotic resistance patterns are predictable.
Treatment usually lasts 6 to 12 months, but it could be cut short if the patient undergoes surgery to remove the infected area. The specific type of surgery depends on the location and severity of the disease. It often involves making an incision to drain abscesses, decompressing a closed space, and removing sinus tracts (abnormal tunnels connecting tissues).
Doctors use imaging techniques to monitor how well the treatment is working.
What else can Actinomycosis be?
When an infection occurs, understanding what caused it can be a tricky process. This is because the rate at which the infection spreads is slow, causing it to mimic conditions like non-cancerous or cancerous tumors, nocardiosis (a type of bacterial infection), and tuberculosis (commonly known as TB).
When doctors are trying to diagnose the issue, they also consider these other possible conditions:
- Aspiration pneumonia (lung infection due to inhaling food, stomach acid, or saliva).
- Appendicitis (swelling of the appendix).
- Diverticulosis (a condition where small pouches form and bulge outward through weak spots in the colon).
- Crohn’s disease (a digestive tract disorder).
- Lung abscess (pus-filled cavity in the lung).
- Fungal pneumonia (lung infection caused by fungi).
- Pelvic inflammatory disease (infection of the female reproductive organs).
- Brain abscess (pocket of infection in the brain).
- Dental abscess (build-up of pus caused by a bacterial infection, usually around a tooth).
Understanding the cause of the infection helps doctors to create an effective treatment plan.
What to expect with Actinomycosis
Long-term use of antibiotics is generally needed, but the outlook is positive. Thanks to improvements such as better mouth care, availability of antibiotics, and advanced surgical procedures, both recovery rates and survival rates have gotten better. For more serious and complex cases, though, both antibiotics and surgery will likely be needed. In these more severe situations, the risk of complications is high and, in some cases, can even lead to death.
Possible Complications When Diagnosed with Actinomycosis
Actinomycosis is a medical condition that can lead to several complications. These include the formation of pus-filled areas in your body called abscesses, and the spreading of the infection to other parts of your body. Certain structures and organs can get affected, like the ribs, vertebrae, and the jawbone, potentially leading to a condition known as osteomyelitis. In some cases, the infection can affect the nervous system, causing illnesses like meningitis, abscesses in the brain, infections in the skull, or infections in or around the spinal cord.
Some other possible complications include liver disorders, heart inflammation, and a severe spread of the infection throughout the body.
The potential complications include:
- Development of abscesses
- Spread of the infection
- Osteomyelitis
- Meningitis
- Brain abscess
- Infection in the skull or around the spinal cord
- Liver disorders
- Inflammation in the heart
- Widespread infection throughout the body
