1348. Mycobacterium Chimera Infection Following Cardiac Surgery: A Review of a Large Cohort of Cases in the United States

BACKGROUND: Mycobacterium chimera (MC) is a nontuberculous mycobacterium associated with infections originating from heater-cooler devices following cardiac surgery globally from 2012 to 2016. Twenty-eight cases occurred within our health system in Southern California, the largest number of cases in the United States to date. We aim to summarize the clinical features, diagnosis, treatments, and outcomes of these cases. METHODS: We reviewed the electronic health records of 28 patients with identified MC infection who had index coronary artery bypass (CABG) and/or valve replacement surgery between 2014 and 2016. All diagnoses were confirmed by cultures speciated to MC by 16S partial DNA sequencing or Karius testing, except for one case. Patients were grouped by clinical presentation of disseminated disease (n = 18) or localized disease (n = 10). Treatment delay was calculated from the time of initial presentation to the start date of antibiotics and evaluation for surgical intervention. RESULTS: All patients who underwent CABG alone (n = 5) developed localized sternal wound infections, whereas patients who had valve replacement surgery (n = 23) developed either localized or disseminated disease. Disseminated disease carried a mortality rate of 40% in those with surgical source control vs. 72% in patients who were not surgical candidates (OR 6.6, 95% CI 0.8–55). The mortality rate of patients with localized sternal wound infections was 11% after incision/drainage and sternal wire removal (n = 9). Delay of antimicrobial treatment greater than 6 months in all 28 patients was associated with a mortality rate of 54% compared with 35% in patients who started treatment within 6 months (OR 2.2, 95% CI 0.47–10.35). Overall mortality rate of patients with MC infection was 42%. CONCLUSION: Disseminated MC infection should be considered early in at-risk patients presenting with constitutional symptoms. In this review of 27 confirmed and 1 probable case of MC infection, disseminated infection only occurred in patients who underwent valve surgery while localized disease occurred in patients who underwent CABG. Surgical source control with early initiation of antimicrobial therapy is associated with improved outcomes. Optimal duration of antimicrobial treatment is still unknown. DISCLOSURES: All authors: No reported disclosures.