Spread of amikacin resistance in Acinetobacter baumannii strains isolated in Spain due to an epidemic strain

Sixteen amikacin-resistant clinical Acinetobacter baumannii isolates from n ine different hospitals in Spain were investigated to determine whether the high incidence of amikacin-resistant A. baumannii was due to the dissemina tion of an amikacin-resistant strain or to the spread of an amikacin resist ance gene, The epidemiological relationship studied by repetitive extrageni c palindromic PCR and low-frequency restriction analysis of chromosomal DNA showed that the same clone was isolated in eight of nine hospitals, althou gh other clones were also Pound, The strains were studied for the presence of the aph(3')-VIa and aac(6')-I genes, which encode enzymes which inactiva te amikacin, by PCR All 16 clinical isolates had positive PCRs with primers specific far the amplification of the aph(3')-VIa gene, whereas none had a positive reaction for the amplification of the aac(6')-I gene. Therefore, the high incidence of amikacin resistance among clinical ri. baumannii isol ates in Spain was mainly due to an epidemic strain, although the spread of the aph(3')-VI gene cannot be ruled out.