*Purpose: Mycobacterium abscessus is increasingly recognised as a human pathogen causing life-threatening infections in immunocompetent patients. Data about clinical outcomes of M. abscessus infections in solid organ transplant (SOT) recipients is limited.

*Methods: We conducted a retrospective cohort study in large academic transplant center in Miami, Florida. The cohort included a retrospective electronic medical record review of all SOT recipients with a positive culture for M.abscessus between January 1st, 2013 and September 30th, 2018. Treatment failure was characterized either by persistent positive culture for M.abscessus and/or lack of radiographic improvement within 12 weeks of treatment initiation, or death attributed to M.abscessus infection.

*Results: A total of 20 patients were included (50% female). 1(5.0%), 2(10.0%), 12(60.0%), 1(5.0%), and 4(20.0%) were kidney, liver, lung, heart, intestine and multivisceral recipients respectively. The median time to infection from SOT was 100 days (IQR: 30-431). 7 patients were not treated as their cultures represented colonization or contamination. 2 of these patients died (unrelated to infection) and 5 had no evidence of M.abscessus infection after one year of follow-up. 13 (65.0%) patients (Kidney 1, Heart 1, lung 7, Liver 1, Intestine 1, and multivisceral 2) patients were treated with combination of antibiotics with a median duration of 160 (IQR: 20-523) days; 4 (20.0%) patients had treatment failure and 3 (15.0%) had unrelated deaths within one year after diagnosis. 7/12(58.3%) lung transplant recipients were diagnosed as active infection and treated with a median duration of 184 (IQR: 20-186) antibiotic days. In our study, M.abscessus massilience (7, 58.3%) was the most common isolate, followed by M.bolletii(4, 33.3%).

*Conclusions: M.abscessus is infrequent in SOT with serious morbidity and potential mortality; is difficult to treat with potential adverse events from combined prolonged antibiotics. Our cohort demonstrated favourable outcomes but we did see a 20% treatment failure. Most organisms were identified in lung recipients yet not all were consider infected and as such were not treated, these patients had no evidence of infection within the study period. Transplant providers should carefully weigh the clinical characteristics in addition to microbiology cultures as M.abscessus could represented colonization with very low or no risk to develop infection and may not require antibiotic treatment in selected patients including lung recipients.

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