Characterization of class I integrons in clinical strains of Salmonella enterica subsp. enterica serovars Typhimurium and Enteritidis from Norwegian hospitals

The characterization of integrons and their promoters in 156 antibiotic-resistant clinical isolates of the important zoonotic pathogens Salmonella enterica subsp. enterica serovars Typhimurium (S. Typhimurium) and Enteritidis (S. Enteritidis) from Norwegian hospitals were performed. Integrons were found in 64 of 66 S. Typhimurium isolates (97 %) and in 20 of 90 S. Enteritidis isolates (22.2 %) with the following sizes; 650, 1000, 1200, 1500, 1600, 1700, 2000 and 2100 bp. The integrons were further sequenced and the aadA1, aadA2, aadA5, aadB, pse-1, catB3, oxa1, dfrA1, dfrA12 and dfrA17 genes, as well as a fragment of the sat1 gene, were found embedded in cassettes. An internal fragment of the purG gene was additionally found as an artefact PCR amplicon.