Flare or foe? - Mycobacterium marinum infection mimicking rheumatoid arthritis tenosynovitis: case report and literature review

Rheumatologic Perspective on Persistent Right-Hand Tenosynovitis Secondary to Mycobacterium marinum Infection

BACKGROUND

Rheumatologic conditions share many symptoms with infectious processes. The immunosuppressive therapies used in rheumatology unfavorably impact any underlying infection. Nontuberculous mycobacteria (NTM) are difficult to grow in culture media and may affect the musculoskeletal system, developing manifestations that may imitate rheumatic inflammatory arthritis. For this reason, surgical debridement and biopsy culture are essential in cases where suspicion remains high.

CASE PRESENTATION

We present the case of a patient with progressively worsening right-hand tenosynovitis who was evaluated for rheumatic conditions given initial negative synovial tissue biopsy cultures. He was finally diagnosed with Mycobacterium marinum infectious tenosynovitis after repeated surgical debridement.

CONCLUSIONS

Our case reinforces the vital role of history gathering in establishing diagnoses and underscores the value of clinical suspicion in patients unresponsive to standard treatment for inflammatory arthritis. Tissue biopsy with culture for acid-fast bacilli is crucial for accurate diagnosis in NTM infection, which may imitate rheumatic inflammatory arthritis. Physicians should be keenly aware of this fastidious, indolent organism in the setting of persistent localized tenosynovitis.

Protective Efficacy of BCG Vaccine against Mycobacterium leprae and Non-Tuberculous Mycobacterial Infections

The genus mycobacterium includes several species that are known to cause infections in humans. The microorganisms are classified into tuberculous and non-tuberculous based on their morphological characteristics, defined by the dynamic relationship between the host defenses and the infectious agent. Non-tuberculous mycobacteria (NTM) include all the species of mycobacterium other than the ones that cause tuberculosis (TB). The group of NTM contains almost 200 different species and they are found in soil, water, animals—both domestic and wild—milk and food products, and from plumbed water resources such as sewers and showerhead sprays. A systematic review of Medline between 1946 and 2014 showed an 81% decline in TB incidence rates with a simultaneous 94% increase in infections caused by NTM. Prevalence of infections due to NTM has increased relative to infections caused by TB owing to the stringent prevention and control programs in Western countries such as the USA and Canada. While the spread of typical mycobacterial infections such as TB and leprosy involves human contact, NTM seem to spread easily from the environment without the risk of acquiring from a human contact except in the case of M. abscessus in patients with cystic fibrosis, where human transmission as well as transmission through fomites and aerosols has been recorded. NTM are opportunistic in their infectious processes, making immunocompromised individuals such as those with other systemic infections such as HIV, immunodeficiencies, pulmonary disease, or usage of medications such as long-term corticosteroids/TNF-α inhibitors more susceptible. This review provides insight on pathogenesis, treatment, and BCG vaccine efficacy against M. leprae and some important NTM infections.

Role of Infections in the Pathogenesis of Rheumatoid Arthritis: Focus on Mycobacteria

Rheumatoid arthritis (RA) is a systemic inflammatory autoimmune disease characterized by chronic erosive polyarthritis. A complex interaction between a favorable genetic background, and the presence of a specific immune response against a broad-spectrum of environmental factors seems to play a role in determining susceptibility to RA. Among different pathogens, mycobacteria (including Mycobacterium avium subspecies paratuberculosis, MAP), and Epstein–Barr virus (EBV), have extensively been proposed to promote specific cellular and humoral response in susceptible individuals, by activating pathways linked to RA development. In this review, we discuss the available experimental and clinical evidence on the interplay between mycobacterial and EBV infections, and the development of the immune dysregulation in RA.