Spread of multidrug carbapenem-resistant Acinetobacter baumannii in different wards of an Italian hospital.

Background: Multidrug-resistant Acinetobacter baumannii (MDRAB) is an important cause of hospital acquired infection. We describe a 7-month outbreak of a MDRAB infection involving various wards of an Italian hospital and an investigation of the possible source of the infection was conducted. Methods: A baumannii was isolated from various biological samples from 22 colonized or infected patients, and was identified and characterized for its antibiotic sensitivity. Typing of A baumannii was performed by multilocus sequence typing (MLST). Investigation of the outbreak involved extensive microbiological sampling of the environment. Results: In 50% of cases the infection occurred in the ICU. Invasive procedures were performed in 63.6% of patients. The strain isolated proved to be resistant to all the antibiotics tested, including carbapenems, and displayed the same allelic profile in all patients. None of the 141 samples taken during environmental monitoring showed positivity for A baumannii. Conclusion: The results of the present study reveal the importance of strict adherence to control measures by all health care personnel and highlight the fact that regular staff training and frequent revision of control measures are essential to the successful management of an outbreak.