Carriage of class 1 integrons and antibiotic resistance in clinical isolates of Acinetobacter baumannii from Northern Spain

A collection of 70 clinical isolates of Acinetobacter baumannii from Bilbao in northern Spain was examined by PCR for the presence of class 1 integron structures. The organisms comprised 21 distinct RAPD genotypes, with 10 di stinct antibiogram patterns. Four different integron structures were detect ed in a total of 59 (84%) of the 70 isolates, with two predominant integron structures found in 20 and 30 isolates each. No clear antibiogram differen ces could be correlated with the presence or absence of integron structures , but sequence analysis of two of the internal integron regions indicated h omology with genes encoding ANT(2") adenyltransferase activity and AAC(6')- Ib acetyltransferase activity. Phenotypic analysis of aminoglycoside resist ance profiles indicated that many isolates produced a combination of aminog lycoside-modifying enzymes, with most of the observed resistance to amikaci n being associated with a gene encoding APH(3')-VI phosphotransferase, as d etected by PCR, RAPD analysis indicated that all the Bilbao isolates produc ing APH(3')-VI were distinct from an epidemic integron-carrying and APH(3') -VI-producing Acinetobacter strain found in other regions of Spain. It is c oncluded that, although class 1 integrons are widely disseminated amongst c linical isolates of A. baumannii from the Bilbao region of Spain, at presen t they are not playing a major role in the dissemination of antibiotic resi stance genes in this region.