Non-tuberculous (atypical) Mycobacteria
Non-tuberculous mycobacteria (NTM) are also known as atypical mycobacteria. These are bacteria that are distantly related to tuberculosis or TB, which is a type of chronic chest infection.
NTM live in soil and water, and we can all get exposed to them. It is thought that toddlers / children ingest them, perhaps through contaminated hands, and the bacteria then travel to the lymph glands in the neck, where the infection then sets in. Usually it happens close to the parotid gland in front of the ear or in the area under the jaw.
The infection is usually caught from the environment, rather than through transmission from one person to another.
NTM causes lymph node infection, but the child usually isn't particularly unwell. A swelling appears and gets bigger over a few weeks, then the skin becomes red and violet in colour. The lump can also develop into an abscess. Sometimes it can burst through the skin, and create a discharging wound.
The key in NTM is that the child is otherwise feeling well. Unlike children with lymphadenitis or neck infection that feel very unwell, children with NTM have a neck lump and maybe even an abscess, but feel perfectly well with it.
How is NTM diagnosed?
NTM is difficult to diagnose. In the early stages there is a neck lump but without any specific features. Often the diagnosis only becomes obvious once skin turns red or violet, or the area starts to discharge pus. Scans and blood tests usually can't give the specific diagnosis. If the wound is discharging doctors will send some of the pus to be analysed. If the diagnosis isn't clear then a biopsy may be performed, and that can give the answer. Identifying NTM in the laboratory is extremely difficult, so even if samples are sent to the laboratories sometimes it is still not possible to get the diagnosis, or it could take 12 weeks for the results to be available.
How is NTM treated?
If identified early, it may be possible to remove the infected lymph nodes. However, it is not often that we can identify NTM in the early stages, and surgery to remove the infection can be quite complex.
Usually we make the diagnosis once the lump has been present a while, and skin has become discoloured. Surgery to remove the nodes would at that stage not usually be an option, because extensive surgery would be required.
If no treatment is given, the infection settles down in one or two years. And that really is the key to management of NTM. Although extensive surgery may be an option, is that worth doing for something that will just settle down? The infection usually occurs close to the nerve that moves the face. Surgery could potentially cause life-long facial paralysis, whereas if we don't operate then the infection settles down of its own accord one or two years later. In general, it is best to just wait, rather than operate and create a life-long problem. That's not to say that thing's are not miserable if there is a leaking wound on the face for two years, it is miserable, but probably a better option than the risk of life-long facial paralysis.
Surgical excision may be suitable for some children. For others, just waiting is a better option. If the wound is discharging badly, then a wound clean out under general anaesthetic can be helpful. The nursing team can give advice on wound care and dressings, and the parents are usually able to provide dressing changes themselves at home.
Antibiotics may also be considered. The problem with NTM is that antibiotic treatment would need to be continued for many months to be effective. There isn't much high quality evidence to say that antibiotics actually do anything. Because the infection just burns itself out one or two years later, showing that antibiotics achieved anything is difficult. And because the infection does just settle, is it worth spending months on antibiotics?
As you can see there are lots of unknown things about NTM. The good thing is that is just settles with time. But we don't quite know what the right management is, so many parents and children experience a difficult few months with a discharging lump before it eventually settles.
Working with an ENT consultant that understands the management of NTM and can discuss the options with you is vital.