RESUMEN
A colistin-resistant Escherichia coli isolate from a commercial poultry farm in China carried two colistin resistance genes, mcr-1 and variant of mcr-3, in an IncP plasmid. The variant of the mcr-3 gene, named mcr-3.11, encoded two amino acid substitutions compared with the mcr-3 gene. A novel genetic structure, ISKpn40-mcr-3-dgkA-ISKpn40, might be the key element mediating the translocation of mcr-3 through the formation of a circular form. The mcr-1 and mcr-3 genes, which are colocated on a plasmid, might pose a huge threat to public health.
Asunto(s)
Colistina/farmacología , Proteínas de Escherichia coli/metabolismo , Escherichia coli/efectos de los fármacos , Escherichia coli/metabolismo , Plásmidos/genética , Polimixinas/farmacología , Animales , Antibacterianos , Pollos , Farmacorresistencia Bacteriana , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Granjas , Pruebas de Sensibilidad Microbiana , Transferasas (Grupos de Otros Fosfatos Sustitutos)/genética , Transferasas (Grupos de Otros Fosfatos Sustitutos)/metabolismoRESUMEN
The novel 63,558-bp plasmid pSA-01, which harbors nine antibiotic resistance genes, including cfr, erm(C), tet(L), erm(T), aadD, fosD, fexB, aacA-aphD, and erm(B), was characterized in Staphylococcus arlettae strain SA-01, isolated from a chicken farm in China. The colocation of cfr and fosD genes was detected for the first time in an S. arlettae plasmid. The detection of two IS431-mediated circular forms containing resistance genes in SA-01 suggested that IS431 may facilitate dissemination of antibiotic resistance genes.
Asunto(s)
Antibacterianos/farmacología , Proteínas Bacterianas/genética , Farmacorresistencia Bacteriana Múltiple/genética , Fosfomicina/farmacología , Plásmidos/química , Infecciones Estafilocócicas/veterinaria , Staphylococcus/genética , Animales , Proteínas Bacterianas/metabolismo , Pollos , China/epidemiología , Granjas , Secuenciación de Nucleótidos de Alto Rendimiento , Pruebas de Sensibilidad Microbiana , Plásmidos/metabolismo , Enfermedades de las Aves de Corral/epidemiología , Enfermedades de las Aves de Corral/microbiología , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Staphylococcus/efectos de los fármacos , Staphylococcus/aislamiento & purificación , Staphylococcus/metabolismoRESUMEN
Recently, a novel variant of the CTX-M enzyme, CTX-M-98, was detected in Escherichia coli isolates from food animals. However, few plasmids carrying blaCTX-M-98 have been fully characterized. In this study, we sequenced the complete pHeBE7 plasmid, an 86,015-bp plasmid that contains the blaCTX-M-98b, blaTEM-1, rmtB, and traT genes, using whole-genome sequencing. The backbone of pHeBE7 shows a high similarity (>99%) to pMC-NDM, which carries the blaNDM-1 gene, however its mosaic regions remain relatively unique among sequenced plasmids. We discovered that a typical ISEcp1-blaCTX-M-IS903 element in the mosaic region harbors the blaCTX-M-98b gene. Conjugation and growth competition assays indicate that pHeBE7 can be easily transmitted and that it confers a limited fitness cost to the recipient cell. The genetic characterization of pHeBE7 may improve our knowledge of how antibiotic resistance disseminates in enterobacteria.
Asunto(s)
Escherichia coli/genética , Plásmidos/genética , Animales , Antibacterianos/farmacología , Pollos/microbiología , Conjugación Genética , Escherichia coli/aislamiento & purificación , Genes Bacterianos , Hígado/microbiología , Pruebas de Sensibilidad Microbiana , Enfermedades de las Aves de Corral/microbiología , Virulencia/genética , Resistencia betalactámica/genética , beta-Lactamasas/genética , beta-Lactamas/farmacologíaRESUMEN
The mcr-1 gene was detected in 5.11% (58/1136) of Escherichia coli isolates of chicken origin from 13 provinces in China. A novel mcr-1 variant, named mcr-1.3, encoding an Ile-to-Val functional variant of MCR-1 was identified in a sequence type 155 (ST155) strain. An mcr-1.3-containing IncI2 plasmid, pHeN867 (60,757 bp), was identified. The transfer of pHeN867 led to a 32-fold increase in the MIC of colistin in the recipient, exhibiting an effect on colistin resistance that was similar to that of mcr-1.