Summary: Mastitis is characterized as inflammation of the mammary gland caused by a variety of bacteria and is a costly disease for the dairy industry. Klebsiella species are important mastitis-causing pathogens not only because treatment with antimicrobials is unsuccessful, but also because their prevalence has been increasing over the years. It is important to monitor development of antimicrobial resistance in Klebsiella because there is a growing concern that it could negatively affect human health and it could be associated with poorer treatment outcomes in dairy cows.