Carbapenem‐resistant Acinetobacter baumannii infections are a worldwide endemic nosocomial threat. Between December 2010 and April 2011, an increase of carbapenem‐resistant A. baumannii infections occurred in several Marseille University Hospitals. The aim of this study was to investigate the increase of carbapenem‐resistant A. baumannii infections and to characterize the mechanisms of carbapenem resistance. The increase was detected by a homemade computer surveillance program, known as EPIMIC, that monitors antibiotic resistance profiles on a weekly basis. During this period, positive samples of carbapenem‐resistant A. baumannii were retrieved from patients hospitalized in different units. Genotyping of the isolates was performed using pulsed‐field gel electrophoresis (PFGE) and multi‐locus sequence typing (MLST), and carbapenemase gene analyses were performed to detect the presence of carbapenemases and to determine the relationships of the isolates. Carbapenem‐resistant A. baumannii were isolated in a total of 11 patients who were hospitalized in different hospitals units. We identified the presence of the blaOXA23‐like carbapenemase‐encoding gene in all of the isolates and found four major PFGE groups and different MLST groups. These results demonstrate a current evolution in the A. baumannii epidemiology in Marseille with a switch from an epidemic situation to an endemic situation and with several circulating clones.