Antimicrobial resistance (AMR) is a global health threat affecting treatment outcome in animals and humans. A pre-requisite for development of AMR reduction strategies is knowledge of antimicrobial use patterns, and how these affect resistance development. The aim of this study was to determine antimicrobial usage (AMU) and whether such usage was associated with AMR in Salmonella from poultry farms in Northwest Nigeria. ; Published version ; An African Research Leader Award to INO from the UK Medical Research Council (MRC) and the UK Department supports INO for International Development (DFID) under the MRC/DFID Concordat agreement that is also Jibril et al. BMC Veterinary Research (2021) 17:234 Page 8 of 10 part of the European Union EDCTP2 programme. The funder had no role in the implementation of the study.
Antimicrobial resistance is a global public health concern, and resistance genes in Salmonella, especially those located on mobile genetic elements, are part of the problem. This study used phenotypic and genomic methods to identify antimicrobial resistance and resistance genes, as well as the plasmids that bear them, in Salmonella isolates obtained from poultry in Nigeria. Seventy-four isolates were tested for susceptibility to eleven commonly used antimicrobials. Plasmid reconstruction and identification of resistance and virulence genes were performed with a draft genome using in silico approaches in parallel with plasmid extraction. Phenotypic resistance to ciprofloxacin (50.0%), gentamicin (48.6%), nalidixic acid (79.7%), sulphonamides (71.6%) and tetracycline (59.5%) was the most observed. Antibiotic resistance genes (ARGs) detected in genomes corresponded well with these observations. Commonly observed ARGs included sul1, sul2, sul3, tet (A), tet (M), qnrS1, qnrB19 and a variety of aminoglycoside-modifying genes, in addition to point mutations in the gyrA and parC genes. Multiple ARGs were predicted to be located on IncN and IncQ1 plasmids of S. Schwarzengrund and S. Muenster, and most qnrB19 genes were carried by Col (pHAD28) plasmids. Seventy-two percent (19/24) of S. Kentucky strains carried multidrug ARGs located in two distinct variants of Salmonella genomic island I. The majority of strains carried full SPI-1 and SPI-2 islands, suggesting full virulence potential ; This work was part-supported by an African Research Leader Award to INO from the UK Medical Research Council (MRC) and the UK Department for International Development (DFID) under the MRC/DFID Concordat agreement that is also part of the EDCTP2 programme supported by the European Union. VG acknowledges Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia for her post-doctoral grant (Grant Number ED481B-2018/018) ; SI
