Objectives: To analyse the evolution and genetic relatedness of Acinetobacter baumannii clonal lineages in
Greece during a 10 year period.
Methods: The study included 94 randomly selected A. baumannii clinical isolates recovered from 2000 to 2009
in eight tertiary Greek hospitals. Carbapenem MICs were determined by agar dilution. PCR was applied for carbapenemase
genes. Isolates were typed by PFGE and tri-locus sequence typing (3LST), and 25 were also typed
by multilocus sequence typing (MLST) developed by the Institut Pasteur, followed by e-Burst analysis.
Results: All isolates were multidrug-resistant (MDR); 54 (57.4%) were non-susceptible to imipenem and/or meropenem.
The blaOXA-58 gene was identified in 51 (94.4%) carbapenem-non-susceptible and 15 (37.5%) carbapenem-
susceptible isolates; other carbapenemase genes were not detected. Eight different PFGE types were
identified. Sequence typing revealed previously characterized 3LST groups (1, 2, 4 and 5) and MLST types
(STs) (1, 2, 15, 45 and 54) and the novel STs 85 (in two distant hospitals) and 86. Eight novel 3LST alleles
were identified. Fifty-two (55.3%) isolates were assigned to 3LST group 1 and ST2 or ST45, both corresponding
to international clonal complex 2 (CC2). Thirty-one (33.0%) isolates were assigned to 3LST group 2 and ST1
(CC1). From 2000 to 2004 63% of isolates belonged to 3LST group 2, but from 2005 to 2009 87.5% of isolates
belonged to 3LST group 1; this shift was accompanied by an increase in carbapenem resistance from 43.5% to
64.6% of isolates.
Conclusions: The emergence of MDR A. baumannii in Greece was associated with CC1 and CC2, which are disseminated
worldwide, often harbouring the blaOXA-58 gene. Novel 3LST alleles and STs were also detected,
underlining an evolutionary divergence in Greece