EC O157:H7 Enrichment Broth

Intended Use

Used as enrichment broth for the rapid growth of E. coli 0157:H7 from food samples.

Composition**

Final pH (at 25°C): 7.1±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 22.5 grams in 1000 ml distilled water. Heat if necessary to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 mins. Mix well and dispense into sterile test tubes.

Principle And Interpretation

E. coli 0157:H7 is a cause of food borne disease in the health industry. Most of the illnesses are associated with eating undercooked, contaminated ground beef; however, contaminated fruits and vegetables are currently increasingly implicated as sources of E. coli O157:H7 infections (1). The major concern is the outbreak of E. coli 0157:H7 food poisoning in United States and Japan. E. coli 0157:H7 has been recognized as a cause of haemorrhagic colitis (3). EC0157:H7 Enrichment broth is based on the formulation described by Rappaport and Henigh (2). EC0157:H7 Enrichment Broth was designed for the rapid enrichment of E. Coli 0157: H7.

Tryptone provides nitrogenous, carbonaceous compounds and other essential growth nutrients. Yeast extract serves as a source of vitamin B complex and other nutrients. Bile salt mixture inhibits most of the gram-positive organisms.

Quality Control

Appearance: Cream to yellow homogeneous free flowing powder

Colour and Clarity of prepared medium: Light amber clear solution without any precipitate

Reaction: Reaction of 2.25% w/v aqueous solution at 25°C. pH : 7.1±0.2

pH: 6.90-7.30

Cultural Response

M1772: Cultural characteristics observed after an incubation at 35 - 37°C for 4 - 6 hours.

Key: *: Formerly known as Enterobacter sakazakii

Storage and Shelf Life

Store below 30°C in tightly closed container and the prepared medium at 2 - 8°C. Use before expiry date on the label.

Reference

1. Ackers, M. L., B. E. Mahon, E. Leahy, B. Goode, T. Damrow, P. S. Hayes, W. F. Bibb, D. H. Rice, T. J. Barrett, L. Hutwagner, P. M. Griffin, and L. Slutsker. 1998. An outbreak of Escherichia coli O157:H7 infections associated with leaf lettuce consumption. J. Infect. Dis. 1771588-1593.
2. Rappaport F and Henigh E., J. Clin. Path., 5:361.
3. Karmali M. A., Petric M., Lim C., et al, 1985, J. Infect. Dis., 151:775.