Exploring Mycobacterium riyadhense: Epidemiology, Clinical Presentation, and Treatment Outcome.

BACKGROUND

Mycobacterium riyadhense, an emerging nontuberculous mycobacterium (NTM), closely resembles Mycobacterium tuberculosis (TB) clinically, often complicating its diagnosis and management.

METHODS

We retrospectively analyzed 8 new cases of M riyadhense infection diagnosed at Prince Sultan Military Medical City from 2019 to 2024. Additionally, a systematic review was conducted of 24 previously reported cases from 2009 to 2025, identified through extensive searches of PubMed and Google Scholar databases. Data extracted included patient demographics, clinical features, diagnostic methods, treatments administered, and clinical outcomes.

RESULTS

Pulmonary infections were predominant and frequently mistaken for TB, resulting in diagnostic delays. Extrapulmonary infections included lymphadenitis and osteomyelitis. A novel association with immune complex glomerulonephritis was identified. Molecular sequencing was critical in confirming diagnoses due to limitations in conventional microbiological techniques. Treatment regimens based on macrolides and fluoroquinolones yielded superior therapeutic outcomes, exhibiting lower relapse rates and fewer adverse effects compared with conventional anti-TB therapy. Surgical interventions played a crucial role in managing complicated or refractory cases.

CONCLUSIONS

Enhancing clinical awareness, employing accurate molecular diagnostic techniques, and adopting targeted antimicrobial therapy are essential for effective management of M riyadhense infections. Further research is needed to optimize treatment protocols and improve patient outcomes.