Genetic insights of antibiotic resistance, pathogenicity (virulence) and phylogenetic relationship of Escherichia coli strains isolated from livestock, poultry and their handlers - a one health snapshot.

BACKGROUND: Pathogenic and non-pathogenic strains of Escherichia coli harbouring antibiotic resistance genes (ARGs) from any source (clinical samples, animal settings, or environment) might be transmitted and contribute to the spread and increase of antibiotic resistance in the biosphere. The goal of this study was to investigate the genome to decipher the repertoire of ARGs, virulence genes carried by E. coli strains isolated from livestock, poultry, and their handlers (humans), and then unveil the genetic relatedness between the strains. METHODS: Whole genome sequencing was done to investigate the genetic makeup of E. coli isolates (n = 20) [swine (n = 2), cattle (n = 2), sheep (n = 4), poultry (n = 7), and animal handlers (n = 5)] from southern India. The detection of resistome, virulome, biofilm forming genes, mobile genetic elements (MGE), followed by multilocus sequence typing (MLST) and phylogenetic analyses, were performed. RESULTS: E. coli strains were found to be multi drug resistant, with a resistome encompassing > 20 ARGs, the virulome-17-22 genes, and > 20 key biofilm genes. MGE analysis showed four E. coli isolates (host: poultry, swine and cattle) harbouring composite transposons with ARGs/virulence genes (blaTEM, dfr, qnr/nleB, tir, eae,and esp) with the potential for horizontal transfer. MLST analyses revealed the presence of ST937 and ST3107 in both livestock/poultry and their handlers. Phylogenomic analyses with global E. coli isolates (human/livestock/poultry hosts) showed close relatedness with strains originating from different parts of the world (the United States, China, etc.). CONCLUSION: The current study emphasizes the circulation of strains of pathogenic sequence types of clinical importance, carrying a diverse repertoire of genes associated with antibiotic resistance, biofilm formation and virulence properties in animal settings, necessitating immediate mitigation measures to reduce the risk of spread across the biosphere.

Reverse vaccinology & immunoinformatics approach to design a multiepitope vaccine (CV3Ag-antiMRSA) against methicillin resistant Staphylococcus aureus (MRSA) - a pathogen affecting both human and animal health.

Infections caused by drug resistant bacteria is a silent detrimental pandemic affecting the global health care profoundly. Methicillin resistant Staphylococcus aureus (MRSA) is a pathogen that causes serious infections in different settings (community, hospital & veterinary) whose treatment remains highly challenging due to its powerful characteristics (antibiotic resistance strategies, virulence factors). In this study, we used reverse vaccinology (RV) approach and designed an immunogenic multi epitope vaccine (CV3Ag-antiMRSA) targeting three potential antigen candidates viz., mecA encoding transpeptidase (PBP2a) protein responsible for conferring methicillin resistance and two virulence determinants - hlgA encoding gamma-hemolysin component A (a pore forming toxin) and isdB encoding iron regulated surface determinant B (heme transport component that allows S. aureus to scavenge iron from host hemoglobin and myoglobin). We employed an array of immunoinformatic tools/server to identify and use immunogenic epitopes (B cell and MHC class) to develop the chimeric subunit vaccine V4 (CV3Ag-antiMRSA) with immune modulating adjuvant and linkers. Based on different parameters, the vaccine construct V4 (CV3Ag-antiMRSA) was determined to be suitable vaccine (antigenic and non-allergen). Molecular docking and simulation of CV3Ag-antiMRSA with Toll Like Receptor (TLR2) predicted its immuno-stimulating potential. Finally, in silico cloning of CV3Ag-antiMRSA construct into pet28a and pet30 vector displayed its feasibility for the heterologous expression in the E. coli expression system. This vaccine candidate (CV3Ag-antiMRSA) designed based on the MRSA genomes obtained from both animal and human hosts can be experimentally validated and thereby contribute to vaccine development to impart protection to both animal and human health.Communicated by Ramaswamy H. Sarma.

Genetic characterization and comparative genomics of a multi drug resistant (MDR) Escherichia coli SCM-21 isolated from a subclinical case of bovine mastitis.

Escherichia coli is one of the major pathogens causing mastitis that adversely affects the dairy industry worldwide. This study employed whole genome sequence (WGS) approach to characterize the repertoire of antibiotic resistance genes (resistome), virulence genes (virulome), phylogenetic relationship and genome wide comparison of a multi drug resistant (MDR) E. coli(SCM-21) isolated from a case of subclinical bovine mastitis in Bangalore, India. The genome of E. coli SCM- 21 was found to be of 4.29 Mb size with 50.6% GC content, comprising a resistome of 22 genes encoding beta-lactamases (blaTEM,blaAmpC), polymyxin resistance (arnA) and various efflux pumps (acr, ade, emr,rob, mac, mar, rob), attributing to the bacteria's overall antibiotic resistance genetic profile. The virulome of E. coli SCM-21 consisted of genes encoding different traits [adhesion (ecp, fim, fde), biofilm formation (csg) and toxin production (ent, esp, fep, gsp)], necessary for manifestation of the infection. Phylogenetic relationship of E. coli SCM- 21 with other global E. coli strains (n = 4867) revealed its close genetic relatedness with E. coli strains originating from different hosts of varied geographical regions [human (Germany) bos taurus (USA, Belgium and Scotland) and chicken (China)]. Further, genome wide comparative analysis with E. coli (n = 6) from human and other animal origins showed synteny across the genomes. Overall findings of this study provided a comprehensive insight of the hidden genetic determinants/power of E. coli SCM-21 that might be responsible for manifestation of mastitis and failure of antibiotic treatment. Aforesaid strain forms a reservoir of antibiotic resistance genes (ARGs) and can integrate to one health micro biosphere.