RESUMO
Objectives: To determine the occurrence of mcr-1 and mcr-2 genes in Gram-negative bacteria isolated from healthy pigs in Great Britain. Methods: Gram-negative bacteria (n = 657) isolated from pigs between 2014 and 2015 were examined by WGS. Results: Variants of mcr-1 and mcr-2 were identified in Moraxella spp. isolated from pooled caecal contents of healthy pigs at slaughter collected from six farms in Great Britain. Other bacteria, including Escherichia coli from the same farms, were not detected harbouring mcr-1 or mcr-2. A Moraxella porci-like isolate, MSG13-C03, harboured MCR-1.10 with 98.7% identity to MCR-1, and a Moraxella pluranimalium-like isolate, MSG47-C17, harboured an MCR-2.2 variant with 87.9% identity to MCR-2, from E. coli; the isolates had colistin MICs of 1-2 mg/L. No intact insertion elements were identified in either MSG13-C03 or MSG47-C17, although MSG13-C03 harboured the conserved nucleotides abutting the ISApl1 composite transposon found in E. coli plasmids and the intervening â¼2.6 kb fragment showed 97% identity. Six Moraxella osloensis isolates were positive for phosphoethanolamine transferase (EptA). They shared 62%-64.5% identity to MCR-1 and MCR-2, with colistin MICs from 2 to 4 mg/L. Phylogenetic analysis indicated that MCR and EptA have evolved from a common ancestor. In addition to mcr, the ß-lactamase gene, blaBRO-1, was found in both isolates, whilst the tetracycline resistance gene, tetL, was found in MSG47-C17. Conclusions: Our results add further evidence for the mobilization of the mcr-pap2 unit from Moraxella via composite transposons leading to its global dissemination. The presence of mcr-pap2 from recent Moraxella isolates indicates they may comprise a reservoir for mcr.
Assuntos
Genes Bacterianos , Variação Genética/genética , Moraxella/genética , Moraxella/isolamento & purificação , Animais , Antibacterianos/farmacologia , Colistina/farmacologia , Elementos de DNA Transponíveis/genética , Farmacorresistência Bacteriana/genética , Escherichia coli/efeitos dos fármacos , Proteínas de Escherichia coli/genética , Fazendas , Transferência Genética Horizontal , Humanos , Proteínas de Membrana/genética , Testes de Sensibilidade Microbiana , Moraxella/classificação , Moraxella/efeitos dos fármacos , Infecções por Moraxellaceae/epidemiologia , Infecções por Moraxellaceae/microbiologia , Infecções por Moraxellaceae/transmissão , Infecções por Moraxellaceae/veterinária , Filogenia , Sus scrofa/microbiologia , Suínos , Doenças dos Suínos/microbiologia , Reino Unido/epidemiologia , beta-Lactamases/genéticaRESUMO
The identification of factors involved in the interaction of Mycobacterium bovis with the hosts will lead to new strategies to control bovine tuberculosis. In this study we compared the transcriptional profile of an attenuated M. bovis strain and a virulent M. bovis strain as a means to elucidate the molecular basis for their differential phenotype. Microarray and RT-qPCR results demonstrated that the expression of mce4D, Mb2607/Mb2608 and Mb3706c were up-regulated in the virulent strain whereas alkB, Mb3277c and Mb1077c were expressed at higher levels in the attenuated strain. These differential expression profiles were confirmed for Mb2607/Mb2608, mce4D, Mb1077c, alkB and Mb3277c during the replication of bacteria inside macrophages.