Risk factors of multidrug resistance in nosocomial bacteremia due to Acinetobacter baumannii: a case-control study

Acinetobacter baumannii is an important nosocomial pathogen. Bacteremia caused by multidrug-resistant A. baumannii (MDRAB) leads to higher mortality and medical cost compared with non-MDRAB bacteremia. We aimed to identify risk factors of multidrug resistance in A. baumannii bacteremia.

A matched case-control study was conducted to compare the differences in risk factors of patients with MDRAB and non-MDRAB bacteremia.

Sixty three patients with MDRAB bacteremia and 63 matched patients with non-MDRAB bacteremia were identified from hospital and laboratory records of the period 1996 to 2002. Multivariate logistic regression analysis identified four independent risk factors associated with multidrug resistance in A. baumannii bacteremic patients: previous colonization with A. baumannii (odds ratio [OR], 7.99; 95% confidence interval [CI], 2.1-30.6; p=0.002), antecedent antimicrobial therapy (OR, 6.10; 95% CI, 1.2-29.9; p=0.026) the number of recently prescribed antibiotics (OR 1.35; 95% CI, 1.0-1.8; p=0.026), and recent invasive procedures (OR, 4.17; 95% CI, 1.6-11.1; p=0.004).

Overall, patients with MDRAB bacteremia had earlier A. baumannii colonization, greater previous exposure to antimicrobial agents and recent invasive procedures. The results of this study demonstrate a rationale for the development of effective interventions to minimize the impact of MDRAB.