Molecular characterization of class 1 integrons in clinical strains of Salmonella Typhimurium isolated in Slovakia

The presence of class 1 integrons was investigated in 156 epidemiologically unrelated Salmonella Typhimurium isolates. Of these 156 isolates, 70 were of definitive phage type DT104 and 86 were strains of various phage type, RDNC and untypable, designated here as non-DT104 strains. Intégrons were found in 47 of DT104 isolates (67.1%), while in all strains with characteristic pentaresistance (R-type ACSSuT) two intégrons 1.0 kb and 1.2 kb in size were found. Among 86 non-DT 104 strains, intégrons with sizes of 1.6 kb and 1.9 kb in four multidrug-resistant strains DT193 and U302 were found. The intégrons from selected strains were further sequenced and the aadA1, aadA2, dlifrl, dhfr12 and blaPSE genes were found embedded in cassettes.