Trends in antimicrobial resistance of Acinetobacter baumannii isolates from a metropolitan Detroit health system.

A phenotypic and genotypic analysis of Acinetobacter baumannii was conducted from 2003 to 2008 in Detroit, MI. The incidence of A. baumannii increased from 1.7 to 3.7/1,000 patient days during the study period. Susceptibility to ampicillin-sulbactam and imipenem decreased from approximately 90% to approximately 40%. Genotyping revealed polyclonality, suggesting either emergence of multiple resistant strains or spread of a common genetic element. The sharp rise mandates major multidisciplinary interventions to optimize management of this multidrug-resistant pathogen.