Virulence factors related to extraenteric Escherichia coli (ExPEC) isolated from lambs with different severity scores of umbilical infections

• Grant number: 24/10328-8
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: May 01, 2025
• End date: November 30, 2027
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Marcio Garcia Ribeiro
• Grantee: Thaís Spessotto Bello
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

The umbilical infections in lambs show a polymicrobial nature and result in significative losses to ovine breeding, due to secondary clinical complications, e.g., organ abscesses, pneumonia, polyarthritis, encephalitis, and septicemia, resulting in early culling, high mortality rates and replacement of animals. Besides etiological complexity, Escherichia coli is the main primary agent of umbilical infections in lambs. It is characterized by versatility, high genetic diversity, adaptability to the environment and different biomes, high complexity of virulence factors (VF), and multidrug resistance to conventional antimicrobials. The pathotypes of E. coli are traditionally classified as enteric (or diarrheagenic-DEC) and extraenteric (ExPEC). The main VF related to extraenteric infections is represented by fimbriae/adhesins, toxins, endotoxins, exotoxins, invasins, iron-uptake mechanisms, and serum resistance. Although umbilical infections by E. coli in lambs represent extraenteric disorders, is unclear the profile or associations of ExPEC genes that could be used as biomarkers of this disease, nor the influence of this VF in severity scores of clinical umbilical infections. In addition, most studies involving omphalopathies in lambs have been performed on diagnosing of microorganisms using traditional phenotypic methods. Considering this scenario, the goal of this study is to investigate the main VF related to ExPEC infections, using a panel of 16 genes: fímbriae/adhesins (sfaDEa, papA, papC, afaBC), toxins (hlyA, sat, cnf1, cdt), siderophores (iroN, irp2, iucD, ireA), invasins (ibeA), and serum resistance mechanisms (ompT, traT, kpsMT II). The detection of genes above will be compared with severity scores of clinical umbilical infections: score 1 (or mild), score 2 (or moderate), and score 3 (or severe), adapted to use in calves. E. coli isolates will be identified at species level using mass spectrometry (MALDI-TOF MS), and subjected to biofilm-formation and in vitro susceptibility testing using nine antimicrobials from seven classes recommended to therapy of bacterial disorders in lambs, including umbilical infections. Overall, is expected to determine the main associations (profile) or higher frequencies of ExPEC genes that may be used as genetic biomarkers of umbilical infections in lambs and likely relationship with severity scores of omphalopathies, as well as to investigate the multidrug resistance of isolates, biofilm-formation, and mortality of animals until 6 months of age.Keywords: ExPEC genes, sheep, omphalopathies, severity scores, MALDI-TOF MS, multidrug