Objective:

To report a case of pneumonia caused by Mycobacterium shimoidei in a young woman with anorexia nervosa and chronic kidney disease, emphasizing the diagnostic and therapeutic challenges and the potential link between anorexia and increased infection risk.

Key Findings:

• M. shimoidei is a rare non-tuberculous mycobacterium with fewer than 40 documented cases worldwide, highlighting the need for awareness among clinicians.
• Next-generation sequencing provided timely diagnosis, confirming M. shimoidei after initial negative tuberculosis tests, demonstrating the importance of advanced diagnostic techniques.
• The patient showed clinical improvement and no evidence of ongoing infection after treatment, underscoring the effectiveness of the chosen therapeutic regimen.

Interpretation:

The case underscores the importance of molecular diagnostics in identifying rare pathogens and suggests that anorexia nervosa may increase susceptibility to infections, warranting further investigation.

Limitations:

• The rarity of M. shimoidei limits generalizability of findings.
• Long-term effects of the infection and treatment on the patient's health remain uncertain.
• Potential for misdiagnosis due to the rarity of M. shimoidei may affect clinical outcomes.

Conclusion:

This case illustrates the diagnostic challenges and treatment considerations for rare non-tuberculous mycobacterial infections, particularly in immunocompromised patients, and highlights the need for awareness and advanced diagnostic methods.