Modified Tryptone Soy Broth (mTSB)

Modified Tryptone-Soy Broth has emerged as the medium of choice for the enrichment of E. coli O157:H7 in red meats and is incorporated into ISO/TS 13136:2012. This medium is not intended for use in the diagnosis of disease or other conditions in humans.

Concern regarding E. coli O157:H7 has grown due to the severity of the disease syndromes caused, and the increase in foodborne infection, so too has the need to optimize methods for its efficient isolation. Symptoms start with severe stomach cramps and watery, bloody diarrhea, and a percentage of individuals infected will develop Haemolytic Uraemic Syndrome (HUS) leading to acute renal failure. In a comparison of four different selective broth media, MTSB was the most productive and selective for the isolation of E. coli O157:H7. mTSB is made selective for O157:H7 by including bile salts in the dehydrated medium, and the addition of novobiocin supplement (X150).