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摘要
Objectives: The aim of this study was to explore the prevalence of bla crx _ m and elucidate the characteristics of transferable bla(CTX-M ) plasmids. @@@ Methods: Escherichia coli were isolated from 10 large-scale duck farms from nine counties and cities in Guizhou Province. They were identified, subjected to antimicrobial susceptibility testing and screened for antibiotic resistance genes. bla(CTX-M)-positive strains were subtyped, and bla(CTX-M-55)-containing strains were further analysed by multilocus sequence typing, conjugation experiments and polymerase chain reaction-based replicon typing. Three transferable plasmids were selected for whole genome sequencing sequencing and further analysis of genetic context. @@@ Results: In total, 128 E. coli strains were identified, and 23 were bla(CTX-M)-positive. Subtype analysis of bla(CTX-M)-positive strains revealed that 23 were bla(CTX-M-55) and one of the strains contained both bla(CTX-M-65) and bla(CTX-M-55). They were divided into 12 multilocus sequence typing types, and 6 were undetermined. bla(CTX-M-55)-bearing plasmids in seven were transferred to E. coli C600 at frequencies between 10(-6) and 10(-9), and bla(CTX-M-55) was found to be located on IncN, IncFII and IncFII-N fusion type plasmids. Three plasmids (IncFII plasmids pEC99_Plas3 and pS1_Plas2 and IncFII-N plasmid pD2_plas2) shared a homologous region of IS26-ARGs-IS26-bla(TEM)-orf477-bla(CTX-M-55)-ISEcp1 Delta-IS26. @@@ Conclusion: Our study demonstrates the environmental presence of bla(CTX-M-55 ) harbouring E. coli in Guizhou. Analysis of the genetic context of bla(CTX-M-55 ) aids in understanding possible dissemination routes of ESBL genes and controlling widespread antibiotic resistance.
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单位广东省农业科学院
