The presence of class 1, 2, and 3 integrons was investigated in four pediatric isolates of Salmonella enterica ser. Typhimurium (S. Typhimurium). A class 1 integron was detected in one S. Typhimurium strain, the only one that also showed resistance to various aminoglycoside antibiotics. This integron, called InJR06, and the aminoglycoside resistance determinants were located in pS06, a large (≥ 55 kb) conjugative plasmid. A single mobile cassette (encoding the aminoglycoside adenylyltransferase ANT(3´´)-Ia) was detected in the variable region of InJR06, while the architecture of the attI1 and attC sites was conserved.Se investigó la presencia de integrones de clase 1, 2 y 3 en cuatro aislamientos pediátricos de Salmonella enterica ser. Typhimurium (S. Typhimurium). Un integrón de clase 1 se detectó en una cepa de S. Typhimurium, la única que además presentaba resistencia a varios antibióticos aminoglucósidos. Este integrón, llamado InJR06, y los determinantes de resistencia a aminoglucósidos se localizaron en pS06, un plásmido conjugativo de tamaño grande (≥ 55 kb). El análisis de la región variable de InJR06 mostró que un casete génico codifica la aminoglucósido adeniltransferasa ANT(3´´)-Ia y que la arquitectura de los sitios attI1 y attC está conservada.This work was supported in part by grants from the University of Buenos Aires, Argentina (TB 039), CONICET (PID 4413), and SEPCYT (PICT 0693) to GG, grants from the Fundación A. J. Roemmers to JDC and grants from the Ministerio de Ciencia y Tecnología, Spain (BMC-2001-2346), and the European Union (LSHM-CT-2003-503335) to JAA. GG is a member of Carrera de Investigador Científico, CONICET, Argentina.Peer reviewed