Genome-wide Genetic Marker Analysis and Genotyping of Escherichia fergusonii strain OTSVEF-60

Abstract

Poultry originated Escherichia fergusonii (POEF), an emerging bacterial pathogen, causes a wide range of intestinal and extra-intestinal infections in the poultry industry which incurred significant economic losses worldwide. Chromosomal co-existence of antibiotics and metal resistance genes has recently been the focal point of POEF isolates besides its pathogenic potentials. This study reports the complete genome analysis of POEF strain OTSVEF-60 from the poultry originated samples of Bangladesh. The assembled draft genome of the strain was 4.2 Mbp containing 4,503 coding sequences, 120 RNA (rRNA = 34, tRNA = 79, ncRNA = 7), and three intact phage signature regions. Forty one broad range antibiotic resistance genes (ARGs) including dfrA12, qnrS1, blaTEM-1, aadA2, tet(A) and sul-2 along with multiple efflux pump genes were detected, which translated to phenotypic resistant patterns of the pathogen to trimethoprim, fluoroquinolones, {beta}-lactams, aminoglycoside, tetracycline, and sulfonamides. Moreover, 22 metal resistance genes were found co-existing within the genome of the POEF strain, and numerous virulence genes (VGs) coding for cit (AB), feo (AB), fep (ABCG), csg (ABCDEFG), fliC, ompA gadA, ecpD etc were also identified throughout the genome. In addition, we detected a Class I integron gene cassette harboring dfrA12, ant (3'')-I and qacE{Delta}-sul2) genes, 42 copies of insertion sequence (IS) elements, and two CRISPR arrays. The genomic functional analysis revealed overexpression of several metabolic pathways related to motility, flagellar assembly, epithelial cell invasion, quorum sensing, biofilm formation, and biosynthesis of vitamin, co-factors, and secondary metabolites. We herein for the first time detected multiple ARGs, VGs, mobile genetic elements, and some metabolic functional genes in the complete genome of POEF strain OTSVEF-60, which might be associated with the pathogenesis, spreading of ARGs and VGs, and subsequent treatment failure against this emerging avian pathogen with currently available antimicrobials.