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Epidemiology and clonality of carbapenem-resistant Acinetobacter baumannii from an intensive care unit in Palermo, Italy

Caterina Mammina1*, Daniela Maria Palma2, Celestino Bonura3, Aurora Aleo1, Teresa Fasciana3, Concetta Sodano4, Maria Antonietta Saporito4, Maria Stella Verde4, Cinzia Calà3, Andrea Neville Cracchiolo2 and Romano Tetamo2

Author Affiliations

1 Department of Sciences for Health Promotion “G. D’Alessandro”, Section of Hygiene, University of Palermo, Palermo, Italy

2 II Intensive Care Unit, ARNAS General Hospital “Civico & Benfratelli, Palermo, Italy

3 Department of Sciences for Health Promotion “G. D’Alessandro”, Section of Microbiology, University of Palermo, Palermo, Italy

4 Laboratory of Microbiology, ARNAS General Hospital “Civico & Benfratelli, Palermo, Italy

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BMC Research Notes 2012, 5:365  doi:10.1186/1756-0500-5-365

Published: 20 July 2012



Multidrug-resistant Acinetobacter baumannii, initially considered as having a poor clinical relevance, is frequently isolated from infection cases in intensive care units. We describe the epidemiology of carbapenem resistant A. baumannii (CRAB) in a general ICU in Palermo, Italy, from October 2010 to March 2011.


58 of 61 isolates exhibited MICs for meropenem or imipenem ≥16 mg/L. Forty-nine carried blaOXA-23 and two blaOXA-58 genes.

Five subtype clusters were detected by rep-PCR. Clusters D and E included 10 isolates that tested negative for the carbapenem resistance genes. MLST attributed all isolates, but two, with sequence type (ST)2, whereas the two remaining isolates with ST78.

The respiratory tract was the most common site of infection (26 out of 36 cases. 72.2%). A high infection related mortality rate was observed (18 out of 35 patients, 51.4%). Nineteen patients tested positive for other multidrug resistant organisms in addition to CRAB. In eight cases isolates belonging to distinct subtype clusters and/or with distinct carbapenemase profiles were identified.


Carbapenem resistance was prominently driven by the dissemination of CRAB isolates belonging to ST2, carrying the carbapenemase gene blaOXA-23. The colonization/infection of some patients by multiple strains is suggestive of an endemic circulation of CRAB.