Genome and plasmid context of two rmtG-carrying Enterobacter hormaechei isolated from urinary tract infections in Brazil.

Abstract

OBJECTIVES\nEnterobacter hormaechei is an important agent of severe infections in critically ill patients. Aminoglycosides are among the main antibiotics for treatment; however the development of resistance is an increasing problem. RmtG is a 16S rRNA methyltransferase, a class of enzymes that confer high-level resistance to clinically relevant aminoglycosides. This study aimed to characterize the full genetic context of plasmids harboring the rmtG gene in two aminoglycoside resistant E. hormaechei isolated in Brazil.\n\n\nMETHODS\nThe rmtG-harboring plasmids were transferred to Escherichia coli J53 recipient strains and fully sequenced in MiSeq sequencing system. Complete genome assemblies were accomplished using combination of Newbler v 3.0, SPAdes 3.10.0 and phrap/cross_match programs. Plasmid sequences were annotated using RAST server and then curated manually using BLAST databases and ISfinder. EasyFig 2.0 was used to map and compare regions of interest containing rmtG of both plasmids.\n\n\nRESULTS\nBoth isolates carry the rmtG genes in IncA/C plasmids of about 152\u2009kb and 235\u2009kb associated to Tn3 transposons. The plasmids contain a transfer region, genes involved in stability, genes codifying resistance to beta-lactams, sulfonamide, and quaternary ammonium compound. One of the plasmids also carries the mrk operon encoding type 3 fimbriae.\n\n\nCONCLUSIONS\nThis first detection of rmtG in E. hormaechei reinforces the ability to horizontal transfer. Location in complex genetic platforms carried by Tn3 transposons in IncA/C plasmids may facilitate dissemination to other Gram-negative pathogens and further limit the treatment options.