An IncX1 plasmid isolated from Salmonella enterica subsp. enterica serovar Pullorum carrying blaTEM-1B, sul2, arsenic resistant operons

Abstract We have identified an IncX1 plasmid named pQJDSal1 from Salmonella enterica subsp. enterica serovar Pullorum ( S. Pullorum). The plasmid is 67,685 bp in size and has 72 putative genes. pQJDSal1 harbors a conserved IncX1-type backbone with predicted regions for conjugation, replication and partitioning, as well as a toxin/antitoxin plasmid addiction system. Two regions (A and B) that have not been previously reported in IncX1 plasmids are inserted into the backbone. Region A (10.7 kb), inserted between parA and taxD , consists of a new Tn 6168- like transposon containing an arsenic resistant operon arsB2CHR and sulfonamide resistance gene sul2 . Region B contains another arsenic resistant operon arsADHR , resistance gene bla TEM-1B and three transposable elements. Conjugation experiments showed that pQJDSal1 could transfer from S. Pullorum to Escherichia coli ( E. coli ) J53. Statistical analysis of 70 sequenced IncX1 plasmids revealed that IncX1 plasmids harbored various antibiotic resistance genes. The results highlight the importance of IncX1 plasmids in disseminating antibiotic resistance genes.