Mycobacterial infections
Mycobacterial infections are systemic infections caused by bacteria from the Mycobacteriaceae family, commonly found in the environment, especially in aquatic settings. These infections can be either chronic or acute and include well-known diseases such as tuberculosis, which is caused by Mycobacterium tuberculosis. Other atypical mycobacterial infections can affect various body parts, including the skin, lungs, and lymph nodes, potentially leading to conditions like lung disease and septic arthritis.
Individuals at higher risk for mycobacterial infections often have weakened immune systems, existing lung diseases, or live in unsanitary conditions, with exposure to contaminated water being a significant factor. Symptoms vary depending on the type of infection but may include persistent cough, weight loss, fever, and skin nodules. Diagnosis typically involves a combination of culture tests, imaging studies, and sometimes tissue biopsies.
Treatment usually consists of long-term antibiotic therapy, and in severe cases, surgical intervention may be necessary. Preventative measures include avoiding stagnant water and ensuring proper sanitation in aquatic environments. Understanding these infections is crucial for effective management and reducing transmission risks.
Mycobacterial infections
- ANATOMY OR SYSTEM AFFECTED: All
Definition
Mycobacterial infections are chronic or acute systemic infections that are spread by a common type of bacteria in the environment, especially aquatic environments. Mycobacterial infections include tuberculosis; atypical mycobacterial infections include those of the skin, bone, soft tissue, lymph nodes, and gastrointestinal tract; they also include lung disease and septic arthritis.
Causes
Mycobacterial infections are caused by one of the species within the gram-positive, aerobic bacteria family called Mycobacteriaceae, which belongs to the Actinomycetales order. Specifically, Mycobacterium tuberculosis causes tuberculosis, M. kansasii causes lung disease, and M. ulcerans and M. marinum cause skin infections. M. avium subspecies intracellulare causes lung disease but primarily affects the lungs of those with acquired immunodeficiency syndrome; M. avium subspecies intracellulare also causes ulcers, diarrhea, fever, pustules, nodules, lesions, and swollen lymph nodes.
Risk Factors
Exposure to contaminated water sources is a major risk factor for mycobacterial infection. Other risk factors are having a preexisting lung disease, having an impaired immune system, undergoing surgery, and having an organ transplant. Also at higher risk are persons with human immunodeficiency virus (HIV) infection and persons living in unsanitary conditions.
Symptoms
Persons with HIV who have a mycobacterial infection often show a cough, weight loss, chest pain, breathlessness, hemoptysis, night sweats, chills, and fever. Persons with a mycobacterial skin infection will often have reddish raised nodules on the elbows, feet, knees, and hands. Pain in the joints, tendons, and bones can be signs of tenosynovitis and of infections that could lead to arthritis and osteomyelitis. Enlarged lymph nodes are often a symptom of persons with mycobacterial infection of the lymph nodes. Signs of tuberculosis include fever and chills, rapid breathing, night sweats, pale skin, prolonged coughing that produces bloody sputum, weight loss, loss of appetite, and pleurisy.
Screening and Diagnosis
Screening methods include blood, bone marrow, lymph node, sputum, and stool cultures. Traditional methods of bacteria analysis, including growth rate and pigmentation studies and acid-fast staining, confirm the identity of the bacteria. A bacterial-species-specific polymerase chain reaction analysis for screening assays has been developed. Deoxyribonucleic acid (DNA) fingerprinting and DNA sequencing techniques are often used for bacteria identification. A tissue biopsy is useful for diagnosis, and X-rays or computed tomography scans may be used to detect internal infection sites.
Treatment and Therapy
Antibiotics, including rifampicin, streptomycin, and tetracyclines have been helpful for preventing the spread of the bacteria. The use of these antibiotics for two weeks to eighteen months can decrease the growth of the bacteria enough to prevent an infection that could lead to lung disease, skin disease, or tuberculosis. If the antibiotics have not been effective enough, then surgery, debridement of the infected tissues, or amputation of infected limbs may be needed to remove the bacteria.
Prevention and Outcomes
To decrease the chance of getting a mycobacterial infection, one should avoid stagnant aquatic environments and should avoid contact with fish and cattle. Chlorination of swimming pools is also an effective method of prevention because chlorine kills the bacteria that can cause these infections.
Bibliography
Heifets, Leonid, ed. Drug Susceptibility in the Chemotherapy of Mycobacterial Infections. Boca Raton, Fla.: CRC Press, 1991.
LaBombardi, Vincent J. “The Genus Mycobacteria.” In Practical Handbook of Microbiology, edited by Emanuel Goldman and Lorrence H. Green. 2d ed. Boca Raton, Fla.: CRC Press, 2009.
Madigan, Michael T., and John M. Martinko. Brock Biology of Microorganisms. 12th ed. Upper Saddle River, N.J.: Pearson/Prentice Hall, 2010.
Malhotra, Akanksha Mimi, et al. "Extrapulmonary Nontuberculous Mycobacterial Infections: A Guide for the General Physician." Clinical Medicine, vol. 24, no. 1, Jan. 2024, doi.org/10.1016/j.clinme.2024.100016. Accessed 4 Feb. 2025.
Schlossberg, David, ed. Tuberculosis and Nontuberculous Mycobacterial Infections. 5th ed. New York: McGraw-Hill Professional, 2006.