Use of rapid on-farm test for decision on clinical mastitis treatment and use of microbiological culture as a selection criteria for selective dry cows therapy

• Grant number: 21/09134-6
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: October 01, 2022
• End date: April 30, 2026
• Field of knowledge: Agronomical Sciences - Veterinary Medicine
• Principal Investigator: Marcos Veiga dos Santos
• Grantee: Breno Luis Nery Garcia
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated scholarship(s): 23/00286-3 - Prediction of clinical mastitis antimicrobial treatment outcome using machine learning, BE.EP.DR

Abstract

The increase in antimicrobial resistance (AR) is a worldwide concern, which has been partially associated with the overuse of antimicrobials in animal production. In dairy cattle, clinical mastitis (CM) treatment and dry-cow-therapy (DCT) are the main causes of antimicrobial use and, for this reason, the responsible antimicrobial use for these purposes can impact public health. In this sense, this proposal is organized into two studies, which aim to evaluate: a) the use of the rapid and direct antimicrobial susceptibility test (RDAST) as criteria for antimicrobial selection in CM treatment and b) the use of on-farm microbiological culture (OFMC) as criteria for selective dry-cow-therapy (SDCT). In study 1, two experiments will be carried out, with the following objectives: a) experiment 1.1: in vitro validation of RDAST results according to standard methodology (agar disc diffusion and minimum inhibitory concentration); and b) experiment 1.2: association between RDAST results and in vivo clinical and microbiological cure rates for mild and moderate CM cases. In study 2, the results of OFMC results will be evaluated as criteria for selection of SDCT at the cow level (treatment of all mammary quarters of cows with e1 samples per mammary quarter with microbial isolation in OFMC) and at the mammary quarter level (treatment only of the mammary quarter with microbial isolation in OFMC) compared to conventional DCT treated cows. It is expected that the results obtained may support the development of selective treatment protocols for CM and DCT, and the judicious use of antimicrobials in dairy herds.