Antibiotic-resistant mechanisms of plasmid pA1137 carrying aminoglycoside resistance gene aacC2 / 军事医学

ABSTRACT

Objective To achieve detailed genomic characterization and investigate the antibiotic-resistant mechanisms of plasmid pA1137 carrying the aminoglycoside resistance gene aacC2.Methods Antibiotic-resistant genes were deter-mined by PCR.Conjugation experiments were performed to verify the transferability of plasmid pA 1137.The minimum in-hibitory concentration(MIC)values of bacterial strains were tested with microdilution method.The genetic background, mobile elements and antibiotic resistance mechanisms of pA 1137 were determined using a whole genome sequencing meth-od.Results Both carbapenem-resistant gene blaIMP-8and aminoglycoside-resistant genes aacC2 and aacA4 were carried by A1137 isolated from Enterobacter cloacae(ECL).aacC2 was located in plasmid pA1137 while the other two resistant genes were observed in chromosomes.Plasmid pA1137 was an IncFⅡplasmid,whose total length was 68.97 kb,and GenBank accession number was MF190369.Plasmid pA1137 contained multiple replicons and intact conjugative transfer regions,so it could be transferred into ECL through conjugation experiments and confer corresponding antibiotic resistance to the transconjugant A1137-EC600.Conclusion IncFⅡ plasmid pA1137 has a single accessory region, the first reported Tn5403-based aacC2-tmrB-related region,which can cause stable inheritance and mediate the resistance to aminoglycoside antibiotics in ECL A1137.