Actinomycosis
Actinomycosis is a rare, slow-burning infection caused by bacteria that live permanently in the mouth, the gut and the genital tract.
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Medicines commonly prescribed for Actinomycosis
For informational purposes only. Always consult a doctor before using any medicine.
Dosage form: TABLET, 500 mgActive substance: amoxicillinManufacturer: Teva Pharma S.L.U.Prescription requiredDosage form: INJECTABLE, 150 mg/mlActive substance: clindamycinManufacturer: Kalceks AsPrescription requiredDosage form: TABLET, 500 mgActive substance: azithromycinManufacturer: Laboratorios Cinfa S.A.Prescription required
Actinomycosis is a rare, slow-burning infection caused by bacteria that live permanently in the mouth, the gut and the genital tract. While the lining is intact they are harmless. The illness starts wherever that barrier is broken: next to a decayed tooth, in a surgical wound, in injured tissue. It develops over weeks and months, and its defining trait is the ability to look like something else — most often a tumour. Actinomycosis does not pass from person to person.
Why your own bacteria turn harmful
These organisms tolerate oxygen poorly, so they need dense, deep tissue with no air. An ordinary scratch does not provide that environment; a decayed tooth, the socket after an extraction, an abdominal wound or irradiated tissue does.
What most often opens the way for them:
- deep decay, inflammation around a tooth root, extractions, fractures and blows to the jaw;
- food or stomach contents passing into the airways;
- abdominal surgery and perforations, including after appendicitis;
- an intrauterine device left in place longer than recommended;
- radiotherapy to the head and neck, which damages the lining and the bone.
The risk is higher with poorly controlled diabetes, a weakened immune system, heavy regular drinking and undernutrition. In a healthy person with well-kept teeth the chance of developing it is very small.
What it looks like
The picture depends on where the infection has taken hold. All forms share one thing: a firm lump that grows slowly, hardly hurts at first, and does not clear with short courses of antibiotics.
- Jaw, cheek, neck. The commonest form. A hard swelling appears near the angle of the lower jaw, making it hard to open the mouth wide and to chew. The skin over it reddens and takes on a purple tinge, then a sinus opens and pus seeps out. Tiny yellow grains are sometimes visible in the pus — clumps of the bacteria themselves.
- Chest. A long-running cough, sometimes with sputum and blood, chest pain, breathlessness, night sweats and weight loss. A sinus can break through the chest wall to the outside.
- Abdomen. A firm mass, more often in the lower right side, a dull ache, altered bowel habit, fever and weight loss. A sinus sometimes opens on the abdominal wall.
- Pelvis. Usually linked to a long-standing intrauterine device: dragging pain low in the abdomen, unusual discharge, bleeding outside the cycle, and a hardened area in the pelvis.
Why it is so often mistaken for a tumour
This is the single most important feature of the disease and it is worth knowing in advance. Actinomycosis ignores anatomical boundaries: it spreads straight through muscle, fat and bone without respecting tissue planes, and on scans it looks like an invading tumour. Neither CT nor MRI can reliably tell it apart from cancer or tuberculosis.
As a result, people with actinomycosis are not uncommonly prepared for surgery for a presumed malignancy, and the real diagnosis emerges afterwards from examination of the removed tissue. The opposite error happens too: a hard lump in the neck is treated for months with short antibiotic courses, shrinks briefly and returns.
The practical conclusion is simple. If a firm lump or a sinus that will not close is behaving differently from what your doctor expects, it is reasonable to ask calmly whether actinomycosis has been considered and whether a sample has been sent for culture in oxygen-free conditions.
When to see a doctor
- a hardened area on the cheek, by the jaw or on the neck lasts longer than two or three weeks;
- an opening has formed in the skin, leaks pus and will not close;
- a cough persists beyond a month, especially together with chest pain and weight loss;
- a painful mass in the abdomen comes with fever and a change in bowel habit;
- unusual discharge or low abdominal pain appears and an intrauterine device has been in place a long time.
Seek help without delay if a high temperature with shivering develops, if swelling in the neck makes it hard to open the mouth, swallow or breathe, or if abdominal pain worsens sharply. Rapidly advancing swelling of the floor of the mouth and the neck is dangerous in its own right, whatever bacterium is behind it.
How the diagnosis is confirmed
The most reliable route is culture of material from the focus in oxygen-free conditions, together with examination of the tissue under a microscope. Both methods have a catch worth knowing about.
Culture is slow, taking up to two weeks, and is easily derailed: if antibiotics were started before the sample was taken, the bacteria do not grow and the result comes back negative despite obvious disease. A swab from an open sinus adds little either, because it is full of unrelated flora. What counts is material taken from deep inside the focus by needle or during surgery, before antibiotics begin.
CT or MRI are needed to see the size of the focus, the tracks and the abscesses, but on their own they do not make the diagnosis. Blood tests only reflect inflammation.
Why antibiotics are prescribed for months
Treatment rests on antibiotics of the penicillin group, to which these bacteria are sensitive. In severe forms it begins intravenously in hospital and then moves to tablets. If there is a penicillin allergy, the doctor selects a substitute from other groups, most often tetracyclines, lincosamides or macrolides.
The course is long, usually several months. The reason is not bacterial resistance but the fact that the organisms sit in dense scar tissue that the drug penetrates poorly. Visible improvement arrives well before the focus is clear, which is exactly why a course abandoned early so often ends in relapse.
A surgeon is needed when there is a large abscess to drain, long sinus tracks or dead tissue. In the pelvic form the intrauterine device is removed. The doctor may shorten the course if the focus has been fully cleared — that decision is taken as follow-up proceeds.
With timely treatment the outlook is good: the disease is curable, though it takes considerable patience.
What lowers the risk
There is no specific prevention, only ordinary measures that close off the entry point.
- treat decay, do not let inflammation around a tooth drag on, and clean teeth and the spaces between them every day;
- do not put off a dental visit after a blow to the jaw or a difficult extraction;
- replace an intrauterine device within the interval your doctor gives, rather than leaving it "another couple of years";
- keep blood sugar under control if you have diabetes.
Online consultation
In an online appointment a doctor can go through how long the lump has been there and how it has changed, judge whether there are grounds to look for an uncommon infection, explain which investigations make sense and in what order, and advise which specialist to see in person.
This material is for information only and does not replace medical advice.
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