Novel trimethoprim resistance gene dfrA34 identified in Salmonella Heidelberg in the USA.
J Antimicrob Chemother
; 74(1): 38-41, 2019 01 01.
Article
en En
| MEDLINE
| ID: mdl-30202900
ABSTRACT
Background:
Trimethoprim/sulfamethoxazole is a synthetic antibiotic combination recommended for the treatment of complicated non-typhoidal Salmonella infections in humans. Resistance to trimethoprim/sulfamethoxazole is mediated by the acquisition of mobile genes, requiring both a dfr gene (trimethoprim resistance) and a sul gene (sulfamethoxazole resistance) for a clinical resistance phenotype (MIC ≥4/76 mg/L). In 2017, the CDC investigated a multistate outbreak caused by a Salmonella enterica serotype Heidelberg strain with trimethoprim/sulfamethoxazole resistance, in which sul genes but no known dfr genes were detected.Objectives:
To characterize and describe the molecular mechanism of trimethoprim resistance in a Salmonella Heidelberg outbreak isolate.Methods:
Illumina sequencing data for one outbreak isolate revealed a 588 bp ORF encoding a putative dfr gene. This gene was cloned into Escherichia coli and resistance to trimethoprim was measured by broth dilution and Etest. Phylogenetic analysis of previously reported dfrA genes was performed using MEGA. Long-read sequencing was conducted to determine the context of the novel dfr gene. Results andconclusions:
The novel dfr gene, named dfrA34, conferred trimethoprim resistance (MIC ≥32 mg/L) when cloned into E. coli. Based on predicted amino acid sequences, dfrA34 shares less than 50% identity with other known dfrA genes. The dfrA34 gene is located in a class 1 integron in a multiresistance region of an IncC plasmid, adjacent to a sul gene, thus conferring clinical trimethoprim/sulfamethoxazole resistance. Additionally, dfrA34 is associated with ISCR1, enabling easy transmission between other plasmids and bacterial strains.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Infecciones por Salmonella
/
Resistencia al Trimetoprim
/
Brotes de Enfermedades
/
Salmonella enterica
/
Genes Bacterianos
Límite:
Humans
País/Región como asunto:
America do norte
Idioma:
En
Revista:
J Antimicrob Chemother
Año:
2019
Tipo del documento:
Article
País de afiliación:
Estados Unidos