Antimicrobial In vitro Activity of Corynebacterium spp. Isolated from Chronic Mastitis Cases in a High Producing Dairy Herd

摘要

Corynebacterium spp. is a contagious pathogen usually enrolled in subclinical mastitis cases in dairy herds. However, this microorganism normally determines high SCC levels and milk production decrease in infected cows. These factors directly affect milk quality and cause important economical losses that are not usually measured by farmers. The contagiously characteristic of this pathogen may cause a high subclinical prevalence in dairy herds, and cows may persist as chronically infected animals. Continuous strategic preventive measures are necessary for its control. Treatment during lactation is not feasible, because the main drugs used for dry cow therapy generally eliminate this microorganism. However, in some reported cases, there are infected cows that remain infected (in the same quarter) in subsequent lactations. By this way, it is important to study the antimicrobial efficacy of commonly used actives against Corynebacterium spp. strains, especially those involved with chronic mastitis casesin dairy herds. The aim of this study was to evaluate antimicrobial in vitro activity of 10 large spectrum antimicrobials against 80 Corynebacterium spp. strains isolated from chronic subclinical mastitis cases.