Mycobacterium marinum granuloma is a rare skin infection caused by a non-ubiquitous atypical mycobacterium. Mycobacterium marinum is found primarily in freshwater and saltwater pools, aquariums, and freshwater and seawater bodies. Infection occurs through skin lesions caused by contact with contaminated water. Nodules and granulomas appear on the skin, usually on the upper limbs. In most cases, the disease is benign, but chronicity and complications may develop if not treated promptly.
History of the disease and interesting historical facts
Mycobacterium marinum was first isolated from aquarium inhabitants in 1926 and later, in 1951, became associated with skin infections in humans. The first cases were reported in aquarium workers and fishermen, giving rise to the name "aquarists' disease." For decades, M. marinum has been studied as one of the representatives of a group of atypical mycobacteria, and its ability to cause localized skin infections has made it a subject of study in dermatology and microbiology.
Epidemiology
Granuloma caused by Mycobacterium marinum is registered relatively rarely. The disease is sporadic with prevalence of cases in countries with warm climates where contacts with contaminated water often occur. According to statistics, the incidence of the disease among the population of aquarists is about 0.04–0.27% of all dermatological infections caused by atypical mycobacteria. The main age group at risk is adults aged 20 to 50 years, especially those who are engaged in fishing or have contact with aquarium water.
Genetic predisposition to this disease
To date, no clear genetic factors have been identified that predispose to the development of infection caused by Mycobacterium marinum. However, studies show that the presence of mutations in genes that regulate the immune response, such as IFNGR1 and IL12RB1, can contribute to a more severe course of the disease. These mutations are associated with disruption of the interferon-gamma and interleukin-12 signaling pathways, which leads to a weakening of the immune defense against mycobacteria.
Risk factors for the development of the disease
Risk factors for developing Mycobacterium marinum infection include:
Contact with contaminated water, especially if the skin is damaged.
Work in fish farms, aquariums and swimming pools.
Chronic skin diseases (psoriasis, eczema).
Immunodeficiency conditions such as HIV infection or taking immunosuppressants.
Exposure to chemical factors such as prolonged exposure to chlorinated water.
Diagnosis of this disease
The main symptoms of infection include the formation of nodules on the skin, most often on the hands and fingers. These nodules may develop into abscesses or ulcers. Laboratory diagnostics include:
Microscopic examination of skin biopsies with Ziehl-Neelsen staining.
A culture method for the isolation of M. marinum, which requires a long incubation period at 30-32°C.
PCR diagnostics for rapid identification of the pathogen. Radiological studies such as ultrasound and MRI can help assess the depth of tissue damage and exclude osteomyelitis. Differential diagnosis is carried out with other skin infections, including staphylococcal and fungal lesions, as well as tuberculosis of the skin.
Treatment
Treatment of Mycobacterium marinum infection includes conservative and surgical methods. The main focus is on pharmacotherapy, which includes the use of antibiotics. Antibiotics such as clarithromycin, rifampicin, and ethambutol are prescribed for a long period of time (at least 3-6 months). In case of deep lesions or the presence of abscesses, surgical opening and drainage may be required. Alternative treatments include thermotherapy (application of heat) and photodynamic therapy.
List of medications used to treat this disease
Clarithromycin
Rifampicin
Ethambutol
Doxycycline
Minoccycline
Disease monitoring
Disease control is carried out based on the clinical picture and laboratory data. It is recommended to periodically evaluate the effectiveness of antibiotic therapy every 4-6 weeks with mandatory correction of the treatment regimen if necessary. The prognosis is favorable in most cases with timely initiation of treatment, but complications in the form of chronicity and the formation of cicatricial changes are possible. A follow-up examination after completion of the course of treatment includes laboratory tests and radiological studies to exclude relapses.
Age-related features of the disease
The disease is more common in adults, but in rare cases it can also be observed in children. In childhood, the infection caused by Mycobacterium marinum occurs with more pronounced inflammatory changes and a tendency to abscess formation. In elderly patients, the disease can be protracted due to weakened immunity and the presence of concomitant chronic diseases.
Questions and Answers
- How can you become infected with Mycobacterium marinum? The infection is transmitted through broken skin when in contact with contaminated water in swimming pools, aquariums or natural bodies of water.
- How long does it take to treat an infection? Treatment can last from 3 to 6 months, depending on the severity of the disease and the depth of tissue damage.
- What complications may arise if left untreated? Complications include chronic infection, abscess formation, and the development of osteomyelitis with deep spread of infection.
- Can the disease recur after treatment? If all recommendations are followed, relapses are extremely rare, however, with immunodeficiency, a return of the disease is possible.
- What preventive measures can be taken to prevent the disease? The main preventive measure is to avoid contact with potentially contaminated water if you have damaged skin and to use protective gloves when working with aquariums and ponds.
