Outcomes of nontuberculous mycobacteria isolation among lung transplant recipients: A matched case-control with retrospective cohort study.

Disclaimer In an effort to expedite the publication of articles , AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time. Purpose Lung transplant recipients are at increased risk for acquiring nontuberculous mycobacteria (NTM), but the clinical significance of NTM isolation, particularly among patients not meeting guideline-endorsed diagnostic criteria for NTM pulmonary disease, is unclear. Methods A case-control study of lung transplant recipients with culture-positive NTM infections treated at a large transplant center during a 7-year period (2013-2019) was performed. Results Twenty-nine cases were matched 1:2 to non-NTM controls. The median time to NTM isolation was 10.7 months post transplant. Only 34.5% of all cases, and half of treated cases, met diagnostic criteria for NTM pulmonary infection. All-cause mortality at 12 months was numerically higher among NTM cases versus controls (20.7% vs 8.6%, P = 0.169); however, no deaths were attributed to NTM. No increase in the 12-month rate of acute rejection was observed (27.6% vs 36.2%, P = 0.477). Recent augmented immunosuppression was associated with increased odds of NTM isolation, while azithromycin prophylaxis was associated with reduced odds of isolation and was not associated with macrolide resistance. Both adverse events and actual or potential drug-drug interactions occurred in more than 90% of treated cases; these events included ocular toxicity, hearing loss, and supratherapeutic calcineurin inhibitor concentrations. Eight of the 14 treated cases (57.1%) required early antibiotic discontinuation due to adverse events or drug-drug interactions. Conclusion Among lung transplant recipients, most patients with NTM isolation did not meet guideline criteria for infection and had outcomes similar to non‒NTM-infected patients, which may reflect transient lung colonization by NTM rather than true disease. As adverse events are common with NTM therapy, limiting unnecessary antibiotic treatment represents an area for future antimicrobial stewardship efforts.