First Report of a Clinical, Multidrug-Resistant Enterobacteriaceae Isolate Coharboring Fosfomycin Resistance GenefosA3and Carbapenemase GeneblaKPC-2on the Same Transposon, Tn1721

Abstract

ABSTRACTIn order to understand the genetic background and dissemination mechanism of carbapenem resistance and fosfomycin resistance inEnterobacteriaceaeisolates, we studied a clinicalEscherichia colistrain HS102707 isolate and anEnterobacter aerogenesstrain HS112625 isolate, both of which were resistant to carbapenem and fosfomycin and positive for theblaKPC-2andfosA3genes. In addition, a clinicalKlebsiella pneumoniaestrain HS092839 isolate which was resistant to carbapenem was also studied. A 70-kb plasmid was successfully transferred to recipientE. coliJ53 by a conjugation test. PCR and Southern blot analysis showed thatblaKPC-2was located on this plasmid. The complete sequence of pHS102707 showed that this plasmid belongs to the P11 subfamily (IncP1) and has a replication gene, several plasmid-stable genes, an intact type IV secretion system gene cluster, and a composite transposon Tn1721-Tn3that harboredblaKPC-2. Interestingly, a composite IS26transposon carryingfosA3was inserted in the Tn1721-tnpAgene in pHS102707 and pHS112625, leading to the disruption of Tn1721-tnpAand the deletion of Tn1721-tnpR. However, only IS26with a truncated Tn21-tnpRwas inserted in pHS092839 at the same position. To our knowledge, this is the first report offosA3andblaKPC-2colocated in the same Tn1721-Tn3–like composite transposon on a novel IncP group plasmid.