Molecular characterization of integrons in Acinetobacter baumannii: Description of a hybrid class 2 integron

Twenty Acinetobacter baumannii strains resistant to various antibiotics wer e analyzed for integron content and sequences of the amplification products . Sixteen clinical isolates had a class 1 integron, 2 contained an addition al class 1 or class 2 integron, but no class 3 integron was detected. Thirt een strains had integrons with a single cassette: aac(3)-Ia (9 strains), an t(2")-Ia- (2 strains), or aac(6')-Ib (2 strains); 1 had aac(6')-Ib and oxa2 0 cassettes and an unknown gene; and I had an integron containing ant(2")-I a and an oxa3 cassette truncated by IS6100. The remaining strains harbored class 1 integrons with gene cassettes previously found in Enterobacteriacea e, One integron had a hybrid structure composed of intI2 and the 3' conserv ed segment of class 1 integrons. These data indicate that integrons pray a major role in multidrug resistance in Acinetobacter.