Counter Clinical Prognoses of Patients With Bloodstream Infections Between Causative Acinetobacter baumannii Clones ST191 and ST451 Belonging to the International Clonal Lineage II

Abstract

This study was conducted to evaluate the possible clinical and bacteriologic features associated with 30-day mortality from Acinetobacter baumannii (A. baumannii) bloodstream infections (BSIs). We conducted a prospective, multicenter, observational study of 181 entire episodes of A. baumannii BSI from six general hospitals between May 2016 and April 2017 in South Korea. Cox proportional-hazards regression model was used to estimate risks of the primary endpoint, i.e., all-cause mortality within 30 days from the initial blood culture. Most (84.5%) of the A. baumannii blood isolates belonged to the international clonal lineage II (ICLII) and 89.5% of the isolates were either multidrug- or extensively-drug resistant. We identified three risk factors including the old age of patient {hazard ratio, 1.033; [95% Confidential Interval (CI), 1.010-1.056]}, the sequential organ failure assessment score [1.133 (1.041-1.233)], and causative A. baumannii sequence type (ST) 191 belonging to ICLII [1.918 (1.073-3.430)], and three protective factors including causative A. baumannii ST451 belonging to ICLII [0.228 (0.078-0.672)], platelet count [0.996 (0.993-0.999)], and definitive therapy within 72 h [0.255 (0.125-0.519)]. Differing 30-day mortality rate in the dominant ICLII was observed by ST, which was much high in ST191 and low in ST451 and it was likely associated with the molecular traits, rather than the drug resistance.