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A1967 - Mycobacterium Abscessus Subspecies Abscessus and Subspecies Massiliense Hybrid Infection in a Lung Transplant Candidate: The Path to Eradication
Author Block: K. Pennington1, P. Escalante2; 1Mayo School of Graduate Medical Education, Rochester, MN, United States, 2Mayo Clinic, Rochester, MN, United States.
Introduction: Mycobacterium abscessus complex (MAbsC) pulmonary disease is being identified with increasing frequency in patients with structural lung disease undergoing transplant evaluation. MAbsC can cause serious pulmonary and soft tissue infections with high morbidity and mortality in lung transplant recipients. MAbsC is resistant to many antibiotics making it difficult to treat. As a result, most transplant centers screen for MAbsC pulmonary infections and will not transplant without sputum eradication. Case: A 54-year-old immunocompromised woman with a medical history notable for end-stage lung disease secondary lymphangioleiomyomatosis (LAM) on sirolimus was undergoing lung transplant evaluation when she was noted to have non-tuberculous mycobacterium on sputum culture. Symptomatically, she had a mild dry cough that had progressed to a productive cough over the preceding weeks, but she did not have a fever, chills or weight loss. Chest computed tomography revealed extensive cystic lung disease consistent with her underlying diagnosis of LAM but no infiltrates. Two sputum samples collected 1 month apart grew MAbsC. Sequencing of the 16S rRNA, erm and rpoβ genes of the isolate identified an M. abscessus subspecies massiliense and subspecies abscessus hybrid with clarithromycin-susceptible erm gene phenotype. The isolate was susceptible to amikacin with intermediate susceptibility to cefoxitin, imipenem, and linezolid. She was initiated on azithromycin, amikacin, and imipenem with the intent of eradication for lung transplantation. Her cough significantly improved, but sputum collected 2 months into treatment was notable for continued MAbsC growth. At that time, her sirolimus was discontinued to assist with eradication of her infection. Most recent sputum culture, collected within the last 30 days, has no growth to date. Conclusion: MAbsC pulmonary disease has a high post-transplant mortality making pre-transplant eradication crucial. Unfortunately, M. abscessus subsp. abscessus has a high-rate of inducible macrolide resistance and low eradication rate (less than 30 percent). However, more recently identified subsp. massiliense does not have inducible resistance to macrolides by erm gene phenotype testing. As a result, M. abscessus subspecies massiliense has a high rate of sputum eradication (more than 85 percent). Thus, distinguishing MAbsC subspecies and determining erm gene phenotype can be critical to predict the likelihood of eradication and lung transplant candidacy. Further studies are needed to determine the outcomes of patients undergoing lung transplantation after therapy for M. abscessus subsp. massiliense.