Amputation of a finger in a patient with multidrug-resistant Mycobacterium marinum skin infection

A Rapid PCR-Based Diagnostic Method for Skin Infection with Mycobacterium marinum

Objective

The increasing incidence of chronic skin infections caused by Mycobacterium marinum, coupled with the time-consuming and low detection rates nature of traditional culture and histological-based diagnostic methods, underscores the need for an expedited approach. The study aims to develop a rapid and efficient method for detecting M. marinum with PCR technology.

Methods

We designed four pairs of primers based on DNA sequences from GeneBank and prior studies, we utilized both PCR and Real-time PCR to identify M. marinum. Specificity and sensitivity assessments were conducted in vitro by DNAs extracted from M. marinum and other bacterial or fungal cultures. Further validation was performed through the implementation of a mouse skin infection model to optimize and confirm the efficacy of the detection method in both fresh and paraffin-embedded skin tissues. The same PCR testing system was further confirmed with paraffin-embedded skin tissues samples from patients as well.

Results

The results of the study indicate promising outcomes for the four-pair primers system. It demonstrated 100% sensitivity in detecting M. marinum from purified cultures, including typical strains and nine clinical isolates, while achieving a specificity of 100%. This specificity was evidenced by the absence of PCR products from 12 bacterial species, 12 fungi species, and six other non-tuberculous mycobacterium (NTM) species. In the animal model, the PCR assay exhibited high detection efficacy for both infected fresh tissues and paraffin-embedded tissues, with a slight superiority observed in fresh tissues. However, the PCR assay exhibited high detection efficacy for clinical paraffin-embedded tissues. These findings collectively underscore the robust detection capabilities of our four-pair primers in both in vitro and in vivo settings.

Conclusion

A sensitive and highly specific rapid detection system has been successfully developed that can be used to detect M. marinum in both infected fresh tissues and paraffin-embedded tissues.

Mycobacterium marinum: A brief update for clinical purposes

Mycobacterium marinum (M. marinum) is a free-living, slow grower nontuberculous mycobacteria (NTM), strictly related to Mycobacterium tuberculosis, that causes disease in fresh and saltwater fish and it is one of the causes of extra-pulmonary mycobacterial infections, ranging in human from simple cutaneous lesions to disseminated forms in immunocompromised hosts. The first human cases of M. marinum infection were reported from skin lesions of swimmers in a contaminated pool, in 1951, in Sweden by Norden and Linell. Two conditions are required to develop M. marinum infection: (1) skin solution of continuity and (2) exposure to the contaminated water or direct contact with fish or shellfish. The so-called "fish-tank granuloma", the most frequent cutaneous manifestation of M. marinum infection, is characterized by a single papulonodular, verrucose and/or ulcerated granulomatous lesion in the inoculum site. Careful patient's history collection, high clinical suspicion and appropriate sample (e.g. cutaneous biopsy) for microbiological culture are crucial for a timely diagnosis. The treatment is not standardized yet and relies on administration of two active antimycobacterial agents, always guided by antimicrobial susceptibility test on culture, with macrolides and rifampin as pivotal drugs, as well as prompt surgery when feasible. In this narrative review, we provide to Clinicians an updated report of epidemiology, microbiological characteristics, clinical presentation, diagnosis, and management of M. marinum infection.

An octopus gift: Mycobacterium marinum multiple skin lesions

Mycobacterium marinum is a nontuberculous mycobacterium responsible of infections in humans, ranging from skin infection to disseminated infection in immunocompromised hosts. Clinical suspicion and prompt diagnosis are crucial to prescribe appropriate antimycobacterial treatment and avoid sequelae.

Mycobacterium agri Skin Infection in a Previously Healthy Patient: A Case Study

Nontuberculous mycobacteria infections present mostly pulmonary characteristics. However, the incidence of skin and soft tissue infections caused by nontuberculous mycobacteria has increased in part due to the increased popularity of cosmetic and plastic surgery. Here, we report a case of Mycobacterium agri infection. The patient underwent a one-year course of anti-infection therapy. To the best of our knowledge, this is the first report of a previously healthy patient presenting a skin and soft tissue infection caused by Mycobacterium agri. Clinical personnel should be aware of possible causes of persistent skin and soft tissue infection after cosmetic and plastic surgery.

Mycobacterium marinum infection simulating chromomycosis: a case report

Skins infections caused by Mycobacterium marinum occur only rarely. We report one case of chronic and extensive M. marinum cutaneous infection simulating chromoblastomycosis and review the pertinent literature. A 52-year-old farmer reported a 32-year chronic skin problem on his right lower limb, resulting from contact with cacti. It consisted of skin lesion presenting with dyschromic atrophic center plate and verrucous borders with hematic crusts, extending from the knee anteriorly to the inferior third of the right leg. Mycobacterium marinum infection was detected by histopathological examination of a skin fragment, culture for mycobacteria and genetic mapping of the culture material. The patient was successfully treated with Ethambutol, Rifampicin and Trimethoprim-Sulfamethoxazole. The clinical and histopathological findings of M. marinum infection is nonspecific showing clinical polymorphism and bacilli are rarely evident on histopathological examination. Given these difficulties, it is essential to perform tissue culture in a suspicious case and it is important keep this infection in mind in patients with long-lasting indolent verrucous lesions and a history of exposure to sea water, freshwater, aquaria or fish.