Hektoen Enteric (SS) Agar

micro lab 2

Purpose of the Hektoen Enteric Agar

• One step further then EMB test

• Isolate Salmonella & Shigella species

• ability to Ferment lactose AND reduce sulfur to hydrogen sulfide

what inhibits gram + growth in the Hektoen Enteric (SS) agar?

Bile salts

Bromothymol blue and fushsin dyes indicate what?

Indicate pH changes

what provides sugar and sulfur source for this?

1. Lactose- sugar source

2. Sodium Thiosulfate- sulfur source

ferric ammonium citrate

provides a source of iron, reacting to hydrogen sulfite to form a black color

Sulfite producers

Salmonella and Proteus , grow black colonies or

blue/ green colonies with a black center

Yellow , Salmon pink colonies indicate what?

Ferment lactose and produce acid but do not produce hydrogen sulfite

Enterics

Blue green with black indicates what?

• Does NOT ferment lactose

• Reduces sulfur to hydrogen sulfide

• Salmonella is what it most likely is

Blue green and NO black indicates what?

• Does NOT ferment lactose

• Does NOT reduce sulfur

• Most likely Shigella

These species of bacteria have in common 1 thing in order to grow on the Hektoen Enteric Agar

• Enteric

• Salmonella

• Shigella

• Proetus

ALL ARE GRAM NEG. GRAM POS WILL NOT GROW IN THIS MEDIA