Use of Eosin Methylene Blue Agar to Differentiate Escherichia coli from other Gram-negative Mastitis Pathogens

Abstract

Mastitis is a continuous concern for dairy producers in the US because of its economic consequences. Coliform mastitis accounts for 20% to 80% of acute clinical mastitis cases and includes gram-negative pathogens Escherichia coli, Klebsiella and Enterobacter species. Rapid identification of the causative organism is essential to implement a prudent treatment plan. Escherichia coli can be rapidly identified with eosin methylene blue (EMB) agar based on the occurrence of a green-metallic sheen that appears on the surface of the bacterial colonies. The primary goal of this study was to evaluate EMB agar for differentiation of E. coli from other gram-negative mastitis pathogens. The secondary goal was to determine the time to first visible sheen.