TOPIC: Chest Infections TYPE: Fellow Case Reports INTRODUCTION: Mycobacterium Simiae (M. Simiae) is a slow-growing photochromogenic mycobacterium transmitted by inhalation of aerosols or by inoculation. It has been recognized as a causative agent of pulmonary and disseminated disease. Lack of a standardized treatment regimen makes treating M.Simiae a challenge. Here we present a case of multi-drug resistant M.Simiae with pulmonary involvement causing massive hemoptysis requiring coil embolization. CASE PRESENTATION: A 72-year-old female known to have bronchiectasis with multiple episodes of hemoptysis requiring coil embolization of bronchial artery presents for evaluation. Bronchoscopy cultures confirm M. Simiae. The patient was started empirically on clarithromycin, ethambutol, and ciprofloxacin while awaiting drug sensitivities. The patient had 2 more admissions for hemoptysis and weight loss, loss of appetite, and night sweats. Drug sensitivities showed resistance to fluoroquinolones, macrolides, trimethoprim/sulfamethoxazole, isoniazid, ethambutol, rifampin, rifabutin, and linezolid. The patient was referred to the National Jewish Medical Center and was started on clofazimine, bedaquiline, and inhaled amikacin. Therapy was continued for 18 months. The patient had no episodes of hemoptysis while being on therapy. The patient had negative bronchoscopic cultures and resolution of associated symptoms. DISCUSSION: The Infectious Diseases Society of America guidelines recommend a clarithromycin-based multi-drug regimen for treatment for M. Simiae, but due to limited in-vitro susceptibility and with little evidence of its correlation with clinical response, the treatment is challenging. In our case, the bacteria being multi-drug resistant makes it even more difficult to treat and hence required a multidisciplinary team approach to determine the best treatment option available. Only 9-21% of isolated M.Simiae are clinically relevant. It rarely affects immunocompetent patients and is mainly described in patients with immunodeficiency syndromes, pneumoconiosis, bronchiectasis, or cystic fibrosis. Very few cases of extra-pulmonary involvement including salivary glands, gastrointestinal tract, skin lesions, osteomyelitis, and lymphadenitis have been reported. The commonly used drug regimen includes clarithromycin with trimethoprim/sulfamethoxazole or moxifloxacin and amikacin. The duration of treatment ranges from 6 to 24 months. Drug susceptibility should be requested in each case. Clofazimine and bedaquiline are used in drug-resistant cases with skin pigmentation being the most common side effect. CONCLUSIONS: The approach to and duration for treatment of multidrug resistance M. Simiae is unclear due to few cases being reported, necessitating further research. Clofazimine and bedaquiline are available options. REFERENCE #1: Lotfi H, Aryan E, Sankian M, Meshkat Z, Khalifeh Soltani A, Alvandi AH, et al. A case of multidrug-resistant Mycobacterium simiae in an elderly woman. Respirol Case Rep [Internet]. 2021 Feb 1 [cited 2021 Apr 25];9(3). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7848708/ REFERENCE #2: Griffith DE, Aksamit T, Brown-Elliott BA, Catanzaro A, Daley C, Gordin F, et al. An Official ATS/IDSA Statement: Diagnosis, Treatment, and Prevention of Nontuberculous Mycobacterial Diseases. Am J Respir Crit Care Med. 2007 Feb 15;175(4):367–416. REFERENCE #3: Javeri H, Vélez-Mejía C, Cadena J. Disseminated Mycobacterium simiae infection in a non-immunosuppressed patient in the USA. IDCases. 2018 Jan 8;11:58–60. DISCLOSURES: No relevant relationships by Mohammed Ali, source=Web Response No relevant relationships by Rahul Dadhwal, source=Web Response No relevant relationships by Jared Head, source=Web Response no disclosure on file for Lauren Howard; No relevant relationships by Salim Surani, source=Web Response