Identification of widespread, closely related Acinetobacter baumannii isolates in Portugal as a subgroup of European clone II

The aims of this study were to determine whether a multidrug-resistant Acinetobacter baumannii clone, known to be endemic in three tertiary-care Portuguese hospitals, had disseminated throughout Portugal, and whether this clone was related to one of the European clones I-III described previously. The isolates were first screened by pulsed-field gel electrophoresis and/or M13 random amplified polymorphic DNA fingerprint analysis. Ten representative isolates were compared by amplified fragment length polymorphism (AFLP) analysis, and were also compared with isolates contained in the AFLP library of the Leiden University Medical Centre. All of the Portuguese isolates clustered in European clone II (clone delineation level > 80%). Following AFLP analysis, seven isolates clustered at > 96%, indicating a striking degree of genetic relatedness and suggesting recent spread of a (sub)clone. Three isolates were slightly more separated from this main group, but all isolates clustered at 87.4%. Thus, the Portuguese multidrug-resistant isolates formed a sub-cluster of European clone II, suggesting that they belong to a recent lineage within clone II.