Class 1 integrons and virulence genes in Salmonella enterica isolates from pork and humans

Abstract In this study, 183 Salmonella enterica isolates were characterised for integrons and virulence genes. Among the isolates, 46% were positive for intI1 , but no isolates carried intI2 or intI3 . Eighteen class 1 integrons (21%) contained resistance gene cassettes (i.e. dfrA1–orfC , dfrA12–aadA2 , bla PSE-1 and aadA2 ) and five class 1 integrons with the dfrA12–aadA2 array were conjugally transferable. Two Salmonella pork isolates of serotypes Albany and Kedougou possessed Salmonella genomic island 1 variants SGI1-G and SGI1-F, respectively. Four class 1 integrons contained an atypical 3′-CS linked to the qacH – sul3 domain, and three were not a sul type. Two novel GyrA mutations (Pro-45→Ser and Met-48→Ile) and three novel ParC mutations (Ser-5→Arg, Thr-31→Met and Leu-77→Arg) were identified in ciprofloxacin-resistant isolates. At least 90% of the Salmonella isolates contained pagC , prgH , sitC , sipB or spaN , whereas all isolates harboured invA , msgA , spiA and tolC .