Principles and diagnostic application of the Hotis test:
(A) The Hotis test was developed by Hotis and Miller (1936) specifically to detect and differentiate the primary contagious mastitis pathogens, distinguishing Streptococcus agalactiae from Staphylococcus aureus in aseptically collected milk samples. The milk is mixed with bromocresol purple (0.5%) and incubated at 37 deg C for 24-48 hours. Streptococcus agalactiae ferments lactose, producing characteristic canary-yellow colonies or buttons along the side and bottom of the tube with an acid (yellow) column, whereas Staphylococcus aureus produces rust-colored or brown colonies/deposits with digest formation.
(B), (C), and (D) are not the primary differential target pair designed for the test.