Clinical manifestations, antimicrobial therapy, and prognostic factors of monomicrobial Acinetobacter baumannii complex bacteremia

Abstract

Bacteremia due to Acinetobacter baumannii complex (ABC), which composed of four genomic species (gen. sp.), is a serious and potentially fatal condition. The epidemiology and outcome of such infections due to individual gen. sp. remain undefined. A retrospective study of patients with monomicrobial ABC bacteremia over six years was conducted at a medical center to determine the association of gen. sp. with clinical outcome. Included were 291 patients with monomicrobial ABC bacteremia. Of them, 222 (76.3%) patients had bacteremia caused by gen. sp. 2, i.e. A. baumannii. The presence of multidrug-resistant phenotype was the only independent predictor of Acinetobacter gen. sp. 2 bacteremia (adjusted odd ratio, 7.5; 95% confidence interval, 3.8-14.7; P < 0.001). Patients with Acinetobacter gen. sp. 2 bacteremia had a higher sepsis-related (P = 0.006) and 30 day (P = 0.028) mortality rates than the non-Acinetobacter gen. sp. 2 group. The fatal outcome was independently associated with high SPAS II scores (P = 0.002), rapidly fatal underlying diseases (P = 0.002), bacteremia caused by Acinetobacter gen. sp. 2 (P = 0.01), inappropriate definitive antimicrobial therapy (P < 0.001), and severe sepsis (P < 0.001). Acinetobacter gen. sp. 2 bacteremia heralded a worse clinical outcome, and therefore the gen. sp. identification of ABC bacteremic isolates is justified.