Mycobacterium marinum hand infection masquerading as tinea manuum: a case report and literature review

Unusual swelling of the hand and multiple nodules over the body - beware of mycobacteria

Atypical mycobacteria can cause rare and atypical infections of the hand. We report the case of an immunocompetent 46-year-old male initially presenting with thumb felon and progressively developing symptoms of carpal tunnel syndrome, tenosynovitis of multiple fingers and a sporotrichoid lymphocutaneous infection causing chronic cutaneous lesions all over the body. We would like to highlight the diagnostic and therapeutic difficulties of these atypical infections, which mimic other conditions and can cause a lot of morbidity.

Mycobacterium marinum hand infection: a case report and literature review

Mycobacterium marinum, a photochromogenic, slow-growing mycobacterium, thrives in both marine and freshwater environments. Optimal growth occurs between 25°C and 35°C, with survival becoming challenging above 37°C. Typically, M. marinum enters the body via skin abrasions, often leading to infections of the upper extremities. Diagnosis of M. marinum infection is frequently challenging and delayed due to the difficult pathogen identification. At present, a standardized treatment protocol has yet to be established. Presented herein is a case study detailing an infection of the right hand's middle finger caused by M. marinum. Notably, his occupation as a chef, handling fish and seafood post-injury, was a significant factor. Histological examination of the skin biopsy and positive acid-fast staining were consistent with a diagnosis of mycobacterial infection. Pathological examination confirmed a skin infection with infectious granuloma, and tissue section acid-fast staining revealed acid-fast bacill. Cultures on Columbia blood agar yielded rough, flattened, yellow-fleshy colonies after 10 days, which was identified as M. marinum through 16S rRNA sequencing. The patient responded well to a 3-month regimen of oral moxifloxacin (0.4 qd) and linezolid (0.6 qd), resulting in rash resolution and pain relief, with no recurrence observed for 1-year follow-up. This report presents the first documented acid-fast staining images of M. marinum tissue sections and colony morphology photographs, offering an in-depth view of M. marinum's morphological characteristics. It aims to enhance awareness of M. marinum infections, underscore the necessity for clinicians to delve into patient histories, and provide a review of the clinical manifestations, diagnostic techniques, therapeutic approaches, and pathogenic mechanisms associated with M. marinum.

Treatment of non-tuberculosis mycobacteria skin infections

Non-tuberculosis mycobacteria (NTM) skin infections have become increasingly prevalent in recent years, presenting a unique challenge in clinical management. This review explored the complexities of NTM infections localized to the superficial tissues and provided valuable insights into the optimal therapeutic strategies. The antibiotic selection should base on NTM species and their susceptibility profiles. It is recommended to adopt a comprehensive approach that considers the unique characteristics of superficial tissues to improve treatment effectiveness and reduce the incidence of adverse reactions, infection recurrence, and treatment failure. Infection control measures, patient education, and close monitoring should complement the treatment strategies to achieve favorable outcomes in managing NTM skin infections. Further efforts are warranted to elucidate factors and mechanisms contributing to treatment resistance and relapse. Future research should focus on exploring novel treatment options, innovative drug development/delivery platforms, and precise methodologies for determining therapeutic duration. Longitudinal studies are also needed to assess the long-term safety profiles of the integrated approaches.

Current treatment options for Mycobacterium marinum cutaneous infections

INTRODUCTION

Mycobacterium marinum is a slowly growing photochromogenic nontuberculous mycobacterium that has special growth characteristics. It causes a uniquely human disease, a cutaneous syndrome named fish tank granuloma or swimming pool granuloma because of the strong epidemiological links with water. The treatment of this disease involves the use of different antimicrobials alone and in combination, depending on the severity of the disease. The antibiotics most frequently used are macrolides, tetracyclines, cotrimoxazole, quinolones, aminoglycosides, rifamycins, and ethambutol. Other approaches include the use of surgery in some cases. New treatment options, like new antibiotics, phage therapy, phototherapy, and others are currently being developed with good in vitro experimental results. In any case, the disease is usually a mild one, and the outcome is good in most of the treated patients.

AREAS COVERED

We have searched the literature for treatment schemes and drugs used for treatment of M. marinum disease, as well as other therapeutic options.

EXPERT OPINION

Medical treatment is the most recommended approach option, as M. marinum is usually susceptible to tetracyclines, quinolones, macrolides, cotrimoxazole, and some tuberculostatic drugs, usually used in a combined therapeutic scheme. Surgical treatment is an option that can be curative and diagnostic in small lesions.

Mycobacterium marinum cellulitis: A fishy etiology

Skin and soft tissue infections account for 2% of emergency department visits annually, though more unusual causative bacteria associated with saltwater exposure may result in morbidity. Mycobacterium marinum represents a rare but important cause of cellulitis, which if untreated or improperly managed, can progress to dactylitis or osteomyelitis. This unusual diagnosis is made more challenging due to the prolonged incubation period of approximately 21 days, temporally separating the inoculation from the disease. Patients will present with a nodular rash in a sporotrichoid pattern. While doxycycline is one antibiotic providing saltwater coverage, M. marinum has variable sensitivities to anti-mycobacterial antibiotics, and thus biopsy helps confirm the diagnosis as well as provide sensitivities for treatment. Emergency clinicians should inquire about environmental risk factors when caring for patients with cellulitis, especially with atypical skin presentations, and consider M. marinum as a rare but important cellulitis etiology.

Nontuberculous Mycobacteria: Ecology and Impact on Animal and Human Health

Nontuberculous mycobacteria (NTM) represent an important group of environmentally saprophytic and potentially pathogenic bacteria that can cause serious mycobacterioses in humans and animals. The sources of infections often remain undetected except for soil- or water-borne, water-washed, water-based, or water-related infections caused by groups of the Mycobacterium (M.) avium complex; M. fortuitum; and other NTM species, including M. marinum infection, known as fish tank granuloma, and M. ulcerans infection, which is described as a Buruli ulcer. NTM could be considered as water-borne, air-borne, and soil-borne pathogens (sapronoses). A lot of clinically relevant NTM species could be considered due to the enormity of published data on permanent, periodic, transient, and incidental sapronoses. Interest is currently increasing in mycobacterioses diagnosed in humans and husbandry animals (esp. pigs) caused by NTM species present in peat bogs, potting soil, garden peat, bat and bird guano, and other matrices used as garden fertilizers. NTM are present in dust particles and in water aerosols, which represent certain factors during aerogenous infection in immunosuppressed host organisms during hospitalization, speleotherapy, and leisure activities. For this Special Issue, a collection of articles providing a current view of the research on NTM-including the clinical relevance, therapy, prevention of mycobacterioses, epidemiology, and ecology-are addressed.