Mycobacteria is a genus of bacteria that includes several human pathogens, including Mycobacterium tuberculosis and Mycobacterium leprae, the infections involved in tuberculosis (TB) and leprosy respectively.[i] For dental professionals, understanding the nature of Mycobacteria is essential. Not only because of the risk of exposure in clinical settings, but also due to their relevance in infection control protocols.
Unique microbiological features
Mycobacteria are aerobic, rod-shaped, non-spore-forming bacilli.[ii] A defining characteristic is their acid-fastness, so named because their lipid-rich cell wall, packed with mycolic acids, retains certain stains even when treated with acid alcohol. This waxy outer layer not only makes them resilient in environmental conditions but also contributes to their resistance to many disinfectants and antibiotics.[iii]
Their slow growth is another hallmark. For example, M. tuberculosis can take 20–24 hours to divide, which is much slower than typical oral flora. This growth rate affects how quickly infections are diagnosed and treated.[iv]
Although leprosy (Hansen’s disease), caused by Mycobacterium leprae[v] is rare in most developed countries, it affects around 200,000 people every year, and there is still a small risk of exposure in the UK.[vi] Oral manifestations of leprosy, such as mucosal ulcers, inflammation of the periodontium and gingiva, and lesions of the palate and nasal bones, can be seen in advanced cases.[vii]
Tuberculosis and dentistry
Tuberculosis is an airborne infectious disease primarily affecting the lungs but potentially impacting any organ system. Globally, TB infects 10 million people every year and 1.4 million people die from the disease annually. About 5,480 people in the UK were infected in 2024, up by 13% from the previous year. Numbers of rifampicin-resistant (RR) or multidrug-resistant (MDR) TB cases also increased slightly compared with 2023 (from 71 to 75 people) and there is evidence that this is likely to increase further.[viii]
While active TB in dental patients is rare, undiagnosed or latent TB does pose a risk. Patients with latent TB are asymptomatic and may not be contagious,[ix] but clinicians should be vigilant during health history reviews and assess for signs such as chronic cough, weight loss, night sweats, or recent exposure.[x]
Dental procedures – such as tooth preparation with a rotary instrument or air abrasion, air-water syringe, ultrasonic scaling and air polishing – create airborne aerosol droplets that can carry disease.[xi] When inhaled, M. tuberculosis faces different environments in the lungs, both extracellular and intracellular, particularly within alveolar phagocytes. The tuberculosis bacterium can tap into the host’s energy and metabolic systems to avoid the immune response, allowing it to thrive as an active or dormant infection.[xii]
From an infection control standpoint, standard precautions should always be followed, but additional measures are warranted if TB is suspected. Elective treatment for patients with suspected or confirmed active TB should be deferred, and the use of high-efficiency particulate air (HEPA) filtration or N95 respirators for dental staff in aerosol-generating procedures should be used, especially if TB status is unknown. Every dental practice should have proper ventilation, and rubber dam isolation should be used where appropriate to reduce the spread.[xiii]
Non-tuberculous mycobacteria (NTM)
Non-tuberculous mycobacteria (NTM), such as Mycobacterium abscessus and M. fortuitum, are environmental organisms found in soil, dust, and water. These bacteria are not transmitted person-to-person but can cause opportunistic infections, particularly in immunocompromised individuals or in post-surgical wounds.[xiv]
Importantly for dental practices, NTM have been implicated in infections linked to contaminated dental unit waterlines (DUWLs). An outbreak of M. abscessus infection in children was traced to DUWLs used during pulpotomy procedures.[xv]
Mitigation against infection
To mitigate against the spread of mycobacteria, the dental team should follow health technical memorandum (HTM) 01-05,[xvi] and manufacturer guidelines for routine maintenance and disinfection of DUWLs. Sterile water or saline should be used during surgical procedures involving bone or soft tissue. DUWLs must be periodically tested to ensure microbial counts are within acceptable limits.[xvii]
Using broad range pathogenic products that include mycobactericidal products is a must to protect patients and the dental team from infection. For example, the BePro range of hygiene products from W&H is bactericidal, mycobactericidal, tuberculocidal, fungicidal and virucidal within extremely short exposure times, to ensure total protection from pathogens.
While the mycobacteria involved in TB and leprosy may not be everyday concerns in dental practice, their potential for causing serious infections, and their resilience in healthcare environments, requires attention. Dental professionals play a crucial role in the prevention of disease transmission, through the maintenance of rigorous infection control practices. Staying informed about pathogens like Mycobacteria can safeguard patients and occupational health in dental practices.
To find out more about the full range from W&H, visit www.wh.com/en_uk, call 01727 874990 or email office.uk@wh.com
Jon Bryant – General Manager W&H UK
[i] Cook GM, Berney M, Gebhard S, Heinemann M, Cox RA, Danilchanka O, Niederweis M. Physiology of mycobacteria. Adv Microb Physiol. 2009;55:81-182, 318-9. doi: 10.1016/S0065-2911(09)05502-7. PMID: 19573696; PMCID: PMC3728839.
[ii] Cook GM, Berney M, Gebhard S, Heinemann M, Cox RA, Danilchanka O, Niederweis M. Physiology of mycobacteria. Adv Microb Physiol. 2009;55:81-182, 318-9. doi: 10.1016/S0065-2911(09)05502-7. PMID: 19573696; PMCID: PMC3728839.
[iii] Sachan RSK, Mistry V, Dholaria M, Rana A, Devgon I, Ali I, Iqbal J, Eldin SM, Mohammad Said Al-Tawaha AR, Bawazeer S, Dutta J, Karnwal A. Overcoming Mycobacterium tuberculosis Drug Resistance: Novel Medications and Repositioning Strategies. ACS Omega. 2023 Sep 1;8(36):32244-32257. doi: 10.1021/acsomega.3c02563. PMID: 37720746; PMCID: PMC10500578.
[iv] Jilani TN, Avula A, Zafar Gondal A, et al. Active Tuberculosis. [Updated 2023 Jan 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513246/
[v] https://www.who.int/news-room/fact-sheets/detail/leprosy
[vi] https://www.gov.uk/government/publications/leprosy-memorandum/memorandum-on-leprosy-2023.
[vii] Vohra P, Rahman MSU, Subhada B, Tiwari RVC, Nabeel Althaf MS, Gahlawat M. Oral manifestation in leprosy: A cross-sectional study of 100 cases with literature review. J Family Med Prim Care. 2019 Nov 15;8(11):3689-3694. doi: 10.4103/jfmpc.jfmpc_766_19. PMID: 31803674; PMCID: PMC6881956.
[viii] National quarterly report of tuberculosis in England: quarter 4, 2024, provisional data. Gov.uk. April 2025. Available at: https://www.gov.uk/government/statistics/tuberculosis-in-england-national-quarterly-reports/national-quarterly-report-of-tuberculosis-in-england-quarter-4-2024-provisional-data Accessed May 2025
[ix] Price C, Nguyen AD. Latent Tuberculosis. [Updated 2024 Jan 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK599527/
[x] https://www.nhs.uk/conditions/tuberculosis-tb/
[xi] Harrel SK, Molinari J. Aerosols and splatter in dentistry: a brief review of the literature and infection control implications. J Am Dent Assoc. 2004 Apr;135(4):429-37. doi: 10.14219/jada.archive.2004.0207. PMID: 15127864; PMCID: PMC7093851.
[xii] Sachan RSK, Mistry V, Dholaria M, Rana A, Devgon I, Ali I, Iqbal J, Eldin SM, Mohammad Said Al-Tawaha AR, Bawazeer S, Dutta J, Karnwal A. Overcoming Mycobacterium tuberculosis Drug Resistance: Novel Medications and Repositioning Strategies. ACS Omega. 2023 Sep 1;8(36):32244-32257. doi: 10.1021/acsomega.3c02563. PMID: 37720746; PMCID: PMC10500578.
[xiii] Chapter 2: Transmission based precautions (TBPs) NHS England. Available at: https://www.england.nhs.uk/national-infection-prevention-and-control-manual-nipcm-for-england/chapter-2-transmission-based-precautions-tbps/ Accessed May 2025.
[xiv] To K, Cao R, Yegiazaryan A, Owens J, Venketaraman V. General Overview of Nontuberculous Mycobacteria Opportunistic Pathogens: Mycobacterium avium and Mycobacterium abscessus. J Clin Med. 2020 Aug 6;9(8):2541. doi: 10.3390/jcm9082541. PMID: 32781595; PMCID: PMC7463534.
[xv] Gianna Peralta, Melissa Tobin-D’Angelo, Angie Parham, Laura Edison, Lauren Lorentzson, Carol Smith, Cherie Drenzek. Notes from the Field: Mycobacterium abscessus Infections Among Patients of a Pediatric Dentistry Practice — Georgia, 2015. April 2016. Center for Disease Control (CDC). Available at: https://www.cdc.gov/mmwr/volumes/65/wr/mm6513a5.htm Accessed May 2025.
[xvi] Health Technical Memorandum 01-05: Decontamination in primary care dental practices. Available at: https://www.england.nhs.uk/estates/health-technical-memoranda/. Accessed May 2025
[xvii] https://www.cqc.org.uk/guidance-providers/dentists/dental-mythbuster-5-legionella-dental-waterline-management
