1355. Efficacy and Tolerability of Linezolid Adjunctive Treatment for Nontuberculous Mycobacterial Infection in Patients with Acquired Anti-Interferon-Gamma Autoantibody

BACKGROUND: Despite a long duration of combined oral antimycobacterial drugs, relapse/ reinfection of nontuberculous mycobacteria (NTM) is common among patients with anti-interferon gamma autoantibodies (anti-IFN-γ auto-Abs). METHODS: We reported here, an interim analysis of the prospective study of 25 patients with anti-IFN-γ auto-Abs, who received oral linezolid (LZD) adjunctive treatment for their NTM infections, at Siriraj Hospital, Bangkok, Thailand, between December 2017 and April 2019. RESULTS: 8 patients (32%) were male, with a median age of 52.5 years. NTM identified among them included Mycobacterium abscessus (n = 19), M. avium complex (MAC) (n = 2), M. fortuitum (n = 2), M. kansasii (n = 1), and both M. abscessus and MAC (n = 1). The median duration of follow-up was 11 months (range 1.6–15 months). LZD 600 mg/day was given until clinical remission, then reduced to 300 mg/day for a total duration of at least 9 months. Other patient’s managements, including choice and duration of other antimycobacterial therapy were determined by the attending physician. Clinical remission was achieved, and LZD was discontinued at 9 months in 10 patients. NTM infection remained active and LZD was continued to 12 months in 4 patients. Two patients only completed 6 months of LZD. Culture proven relapse of M. abscessus occurred in 3 patients during LZD treatment, and 1 patient developed M. haemophilum infection after discontinuation of all drugs for 3 months. One patient was retreated with intravenous antimycobacterial drugs based on clinical suspicious of relapse NTM infection. LZD-related serious adverse events leading to discontinue of LZD occurred in 5 patients; severe myelosuppression (n = 1), peripheral neuropathy (n = 2), exfoliative dermatitis (n = 1), and idiopathic increased intracranial pressure (n = 1). Anemia occurred in 3 patients during the 600 mg LZD once-daily treatment period. No patient developed anemia after LZD was adjusted to 300 mg twice daily. The rate of peripheral neuropathy was similar throughout the study period. CONCLUSION: LZD might reduce the rate of relapsed/ reinfection of NTM infection in these patients. LZD 300 mg twice daily was less toxicity and more tolerable than 600 mg once daily. Long-term study with this modified regimen is now on-going. DISCLOSURES: All authors: No reported disclosures.