SHM Converge Scientific Abstract ePoster Gallery-Uncharted Territory in Mycobacterial World: Second Case Report in Us

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This case report describes a rare pulmonary infection caused by <em>Mycobacterium shimoidei</em>, a slow-growing nontuberculous mycobacterium first identified in Japan in 1968 and reported only about 15 times worldwide. It is presented as the second reported case in the United States.

The patient was a 68-year-old man with heavy smoking history, COPD, and asbestos exposure who developed worsening chronic cough with sputum, night sweats, weight loss, and malaise. He had been treated repeatedly with azithromycin for presumed pneumonia without improvement. Chest imaging showed a complex cavitary lesion in the left upper lobe with surrounding consolidation and nodular densities. Bronchoscopy revealed mucosal inflammation, and bronchial lavage cultures grew acid-fast bacilli later identified as <em>M. shimoidei</em>.

He was started on clarithromycin, rifabutin, and ethambutol. Drug susceptibility testing showed sensitivity to ethambutol and rifabutin but resistance to clarithromycin. Despite treatment, his symptoms persisted and follow-up CT demonstrated progression of the cavitary lesion. Because medical therapy appeared to have failed, a multidisciplinary team decided to proceed with left upper lobectomy.

The surgery was uncomplicated, symptoms improved significantly, and pathology showed non-caseating granulomatous inflammation. Over five years of follow-up, he remained symptom-free, with negative sputum AFB cultures and no radiographic recurrence.

The report highlights that <em>M. shimoidei</em> usually affects middle-aged men with risk factors such as immunosuppression, underlying lung disease, prior TB, or lung cancer, and its clinical presentation can resemble tuberculosis. Although triple-drug therapy with clarithromycin, rifabutin, and ethambutol is commonly used, there is no established standard treatment. In selected patients, surgical resection may be a curative option when antibiotic therapy fails.

Asset Subtitle

Aung Naing

Meta Tag

Author List Aung Naing, Erin Bartholomew, Nadeem Inayet

Category Clinical Vignettes

Concept Mycobacterium shimoidei

Concept Pulmonary infection

Concept Diagnostic Workup

Concept Risk Factors

Concept Antibiotic Therapy

Distinguished Non-Finalist

Presenter Organization EVMS at ODU

Presenting Author Aung Naing

Track Adult

Keywords

Mycobacterium shimoidei

nontuberculous mycobacteria

pulmonary infection

cavitary lung lesion

chronic cough

bronchoscopy

acid-fast bacilli

rifabutin

ethambutol

lobectomy

Mycobacterium shimoidei

Pulmonary infection

Diagnostic Workup

Risk Factors

Antibiotic Therapy