Epidemiology and clinical outcomes associated with extensively drug-resistant (XDR)

Although infections caused by Acinetobacter baumannii are often healthcare-acquired, difficult to treat, and associated with high mortality, epidemiologic data for this organism are limited. We describe the epidemiology, clinical characteristics, and outcomes for patients with extensively drug-resistant Acinetobacter baumannii (XDRAB). Retrospective cohort study. Department of Veterans' Affairs Medical Centers (VAMCs). Patients with XDRAB cultures (defined as nonsusceptible to at least 1 agent in all but 2 or fewer classes) at VAMCs between 2012 and 2018. Microbiology and clinical data was extracted from national VA datasets. We used descriptive statistics to summarize patient characteristics and outcomes and bivariate analyses to compare outcomes by culture source. Among 11,546 patients with 15,364 A. baumannii cultures, 408 (3.5%) patients had 667 (4.3%) XDRAB cultures. Patients with XDRAB were older (mean age, 68 years; SD, 12.2) with median Charlson index 3 (interquartile range, 1-5). Respiratory specimens (n = 244, 36.6%) and urine samples (n = 187, 28%) were the most frequent sources; the greatest proportion of patients were from the South (n = 162, 39.7%). Most patients had had antibiotic exposures (n = 362, 88.7%) and hospital or long-term care admissions (n = 331, 81%) in the prior 90 days. Polymyxins, tigecycline, and minocycline demonstrated the highest susceptibility. Also, 30-day mortality (n = 96, 23.5%) and 1-year mortality (n = 199, 48.8%) were high, with significantly higher mortality in patients with blood cultures. The proportion of Acinetobacter baumannii in the VA that was XDR was low, but treatment options are extremely limited and clinical outcomes were poor. Prevention of healthcare-associated XDRAB infection should remain a priority, and novel antibiotics for XDRAB treatment are urgently needed.