2023 Volume 76 Issue 6 Pages e170-e176
Dairy cows suffering from mastitis are mainly treated by administering antimicrobials. In this study, we evaluated the usefulness of CHROMagarTM Mastitis, which can estimate the causative pathogenic bacteria based on the color of the colonies. In addition, we evaluated the usefulness of performing the estimation of antimicrobial susceptibility using penicillin-containing agar and placing antimicrobial-containing discs on the same agar in order to simply estimate antimicrobial susceptibility. One hundred thirty-five samples of mastitis milk were collected and tested. The results for Escherichia coli, Klebsiella spp., Staphylococcus aureus, and Streptococcus uberis, which are considered the major causative bacteria of mastitis, were in agreement with the identification of 100, 100, 87, and 42%, respectively. Penicillin-containing agar made it possible to estimate susceptibility to penicillin, and by combining the antimicrobial susceptibility discs, susceptibility to other antimicrobials could also be estimated. The present method is expected to facilitate the appropriate choice of antimicrobials by providing simple estimates of mastitis-causing bacteria and antimicrobial susceptibility.
