VIRULENCE FACTORS AND ANTIMICROBIAL SENSITIVITY PROFILE OF E. coli CAUSING MASTITIS IN DAIRY CATTLE IN THE ARAÇATUBA REGION, SP

• Grant number: 25/25224-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2026
• End date: January 31, 2027
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Ricardo Antonio Pilegi Sfaciotte
• Grantee: Luana Medeiros Rezende Mendonça
• Host Institution: Faculdade de Medicina Veterinária (FMVA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil

Abstract

Bovine mastitis is one of the main diseases affecting dairy farming, causing significant economic losses due to decreased milk production, milk disposal, and costs related to treatment and animal replacement. Among the etiological agents, Escherichia coli stands out for its remarkable adaptability and antimicrobial resistance, representing an increasing challenge for both animal and public health. The general objective of this project is to characterize E. coli strains isolated from clinical and subclinical mastitis in dairy cows from the Araçatuba region, identifying their virulence factors and antimicrobial susceptibility profiles. Milk samples will be collected from animals diagnosed with mastitis following strict aseptic procedures. Bacterial isolation will be performed on blood agar and identified using classical biochemical tests. Confirmed E. coli strains will be evaluated for antimicrobial susceptibility using the disk diffusion method, with antibiotics of veterinary and public health relevance, according to CLSI recommendations. The isolates will also undergo phenotypic and genotypic characterization, including tests for biofilm formation and multiplex PCR analyses for the detection of virulence genes (EHEC, EPEC, ETEC, EIEC, EAEC) and resistance, with emphasis on ¿-lactam antibiotics. The analysis of the results will provide a regional overview of antimicrobial resistance and the presence of virulence genes in E. coli associated with bovine mastitis. It is expected to identify multidrug-resistant and biofilm-producing strains with the potential for persistence and dissemination within herds. Statistical analysis will be descriptive, complemented by cluster analysis based on genetic and phenotypic profiles of the isolates. The results will contribute to understanding the epidemiology of E. coli in bovine mastitis, supporting control strategies, rational antimicrobial use, and the prevention of resistant strain dissemination. The study aligns with the "One Health" approach, reinforcing the importance of integrated monitoring between animal, human, and environmental health. By identifying virulence factors and resistance mechanisms, the project aims to promote more sustainable practices in dairy farming, improve therapeutic protocols, and reduce the economic and health impacts of this disease. (AU)