I have been aware of Nontuberculous Mycobacteria (NTM) for some time, but three years ago I still knew relatively little of the bacteria’s key characteristics, since the majority of our attention in healthcare water system environments is focused on Legionella and Pseudomonas aeruginosa bacteria. However, when I was informed about the NTM outbreak of Mycobacterium abscessus at the Royal Papworth Hospital in 2019,1 and the fact that the investigation confirmed water supply as the source, this further awakened my interest, and I felt that I needed to understand how this bacterium can affect our heath and how (if at all) we can control it
Ubiquitous in the environment
Nontuberculous mycobacteria, shortened to NTM, are ubiquitous in the environment, and are bacteria found in soil, dust, and water, including natural water sources (such as lakes, rivers, and streams) and municipal water sources (such as water that people drink or shower in).2 As with the majority of bacteria, there can be many different strains; in fact there are approximately 180 strains of NTM bacteria and more than 170 different species
The history of this bacterium dates to the 19th century, when ‘tuberculosis’ in chickens was first described, in 1868.3 In 1890, this organism was recognised in the laboratory to be distinct, or different from, M. tuberculosis, the cause of tuberculosis. The organism which caused disease in chickens was later identified as M. avium. Because this organism did not cause characteristic disease when injected into guinea pigs, it was recognised as distinct from M. tuberculosis, and was not believed to cause disease in humans until the 1930s.
In 1943 a man with underlying silicosis (a form of lung disease) was the first cases of lung disease due to M. avium complex, and by the 1950s, pulmonary disease due to NTM became more commonly recognized.
It is worth mentioning that under the microscope, nontuberculous mycobacteria and tuberculosis appear very similar. Most laboratories are capable of distinguishing between tuberculosis and nontuberculous mycobacteria, but fewer are equipped to determine exactly which NTM organism it might be, and its susceptibility to antibiotics, and of course it is important to be able to determine the difference to offer the optimal treatment for NTM.
The importance of precisely identifying the organism present can be illustrated with Mycobacterium gordonae and Mycobacterium scrofulaceum. While the two are very similar, and react the same way in many lab tests, they react in different ways in the human body; one organism causes disease; the other does not.
Bacteria are more prevalent when human immunodeficiency is heightened, for instance when somebody is exposed to virus and various forms of illnesses. In the case of virus (such as HIV), the patient’s infection is distributed throughout the body, affecting skin, soft tissues, and bones/joints. We should thus always approach bacteria that can cause illness with the upmost care, striving to understand its characteristics, so that we are better able to control it, and – where possible – to eliminate the bacteria from the route of exposure. We know that NTM bacteria can enter people’s lungs and other organs naturally through exposure in the environment, and are particularly likely to affect patients and/or people who are immunocompromised. While the microorganism is not usually harmful to the general population, it can cause lung infections in some individuals who already have specific underlying respiratory conditions. Knowing the path that the bacteria can take to enter our bodies is beneficial, in that makes us more aware of the high-risk areas (hospitals, clinics, augmented care and other high-risk (such as ICU and ITU) settings), and of the degree of risk that patients are exposed to.
Specific risk assessments
These areas should undergo a specific risk assessment (especially if NTM has been found to be present) with a view to ensuring that sound hygiene practices and effective water system management are in place, enabling us to concentrate our efforts to address the contamination
Why – you may ask – is all of this is so important? When a person is affected by NTM bacteria, treatment is not always needed, but when it is, it can be via a combination of antibiotics, administered intravenously (through a vein) and orally (swallowed), and unfortunately this treatment may need to be prescribed for a prolonged period due to the difficulty in removing build-up of phlegm trapped in the lungs.4 Chest physiotherapy and regular exercise can help NTM infections go away without treatment, but it can take a long time to kill all the NTM bacteria, so infected patients may need to treated for a year or two. If one takes all one’s medication correctly, and as prescribed, the infection should resolve. However, it is possible to re-contract an NTM infection, especially if the medication prescribed is not taken regularly. The bacteria can also become resistant to the antibiotics being taken, making the infection much harder to treat. Adding to the difficulties, the bacteria can still exist even after samples come back negative. NTM infections are not thought to be transmissible between individuals except in very specific circumstances (for example, M. abscessus infection can pass between people with cystic fibrosis). To reduce the risk of cross-infection, it is sensible to adopt good hygiene precautions, such as coughing into a tissue and disposing of it in a covered bin.5
When commencing treatment of an individual, often you will be trying to get rid of the microbe. In some patients, either due to a lack of tolerance of particular drugs, the drugs’ lack of effectiveness, or the fact that the disease is too severe, the aim may rather be to keep the patient stable in the knowledge that while you may not actually eliminate the bacteria, you may prevent further lung damage.
Water safety in UK healthcare is regulated by the Health and Safety Executive, with the consent of the Secretary of State for Health, who has approved the Code of Practice ACoP L8,6 which gives clear guidance on how to comply with the law. Health Technical Memorandum (HTM) 04-01, issued by the Department of Health & Social Care, also sets clear guidelines on good water quality management.
However, none of the aforementioned guidance covers the management or control of NTM bacteria in healthcare. The Health and Safety Executive (HSE) provides a list in the Approved List of biological agents – Advisory Committee on Dangerous Pathogens (Third edition 2013) of a range of pathogens that fall under the high-risk category.6 This list includes a wide range of Mycobacteria, including one mentioned earlier – Mycobacterium scrofulaceum (pathogen hazard group 3. Vaccine available). Mycobacterium scrofulaceum is a slowgrowing, Nontuberculous Mycobacterium that belongs to the Mycobacterium avium complex.
Preventing the bacterium taking hold
With the information that is available to us, how can we prevent or control this bacterium from taking hold in our domestic water systems within healthcare; can we prevent the bacteria entering our water distribution system? The latest study reported via the News Medical Life Science interview with Dr Michael Loebinger conducted by April CashinGarbutt, MA (Cantab), showed an increase in the number of NTM isolates from 137 in 2000 to 759 in the 2013.7 The increase in NTM bacteria may be due to the increase in elderly population, a rise in the number of people with chronic lung disease and underlying diseases, and the fact that we are getting better at killing other bugs, and so NTM have less competition
It is widely acknowledged that NTM bacteria in patients are proving to be difficult to treat, and with this in mind and referring to the outbreak of Mycobacterium abscessus at the Royal Papworth Hospital in 2019 mentioned earlier, once we know that the bacteria are present in the water system, we should prevent the contamination reaching our patients wherever possible
This is normally achieved by implementing the correct point-of-use filtration at our water outlets (taps, showers). It is very important to ensure the filtration product used is of a type that will remove the NTM bacterium, as not all POU filters developed take this bacterium into consideration.
Water filters must be specifically tested on their retention of NTMs, rather than simply based on the theory that if Legionella / Pseudomonas aeruginosa bacteria are removed, then NTM bacteria should be too. Therefore, only filters on the market that have been tested against NTMs and provide 100% absolute retention guarantee, including a validation guide, should be considered
Karina Jones
Karina Jones MIHEEM, MIET, MWMSoc, MWES, of Eta Projects, is an IHEEM-registered Authorising Engineer (Water), and a member of the Institute’s Water Technical Platform. She has extensive water management experience. She provides independent advice to clients across a range of industries, but specialises in healthcare. She is also a member of the Water Management Society, the Institution of Engineering and Technology, and the Women’s Engineering Society (MWES). She has considerable experience providing advice on water hygiene management, advising clients on the legal drivers for statutory obligations and ACoP L8 compliance, and providing comprehensive guidance on microbiological waterborne contamination to NHS Trusts across the country
References 1 Mycobacterium abscessus, Royal Papworth Hospital NHS Foundation Trust. https://royalpapworth.nhs.uk/ mycobacterium-abscessus 2 Nontuberculous Mycobacteria. Aksamit T, Carreon M, Daley CL, Griffith DE, Levinger A, Estrada-Y-Martin RM. CHEST Foundation, 22 April 2021. https://tinyurl. com/4v3twua6 3 Mycobacterial skin infections National Jewish Health. Reviewed by Shannon H. Kasperbauer, MD. 1 July 2017) https:// tinyurl.com/uc8skuc9 4 Patient Information. For patients with Nontuberculous Mycobacterium infections (NTM). Worcestershire Acute Hospitals NHS Trust. https://tinyurl. com/48s6uh53 5 Non-tuberculous mycobacterial infection (NTM). Asthma + Lung UK. https:// tinyurl.com/22bh5crd 6 The Approved List of biological agents. Advisory Committee on Dangerous pathogens. Health & Safety Executive 2000. https://www.hse.gov.uk/pubns/ misc208.pdf 7 NTM lung infections. Cashin-Garbutt A. News-Medical.net. 23 November 2016. https://www.news-medical.net/ news/20161123/NTM-lung-infections.aspx