Salmonella and Shigella

Non-Lactose Fermentors

Salmonella Shigella Proteus

Salmonella

1. Salmonella
a. Growth of Salmonella on MacConkey agar: Non-lactose fermenter (colonies pale colorless)b. Growth of Salmonella on SS agar: Non-lactose fermenter with black center due to the production of H2Sc. Biochemical tests of Salmonella:• Indole: negative• Citrate: positive• TSI: K/A, Gv H2S+• Motility test: motile• Urease test: negatived. Serology test for Salmonella infection : Widal test

Shigella

2. Shigella
a. Growth of Shigella on MacConkey agar: Non-lactose fermenter (colonies are pale colorless)b. Growth of Shigella on SS agar: Non-lactose fermenterc. Biochemical tests of Shigella:• Indole: variable• Citrate: negative• TSI: K/A, G- H2S-• Motility test: non-motile• Urease test: negative

Shigella Salmonella Motility + - Glucose AG (except S. typhi) A Indole - + H2S + -

3. Proteus

a. Growth of Proteus on MacConkey agar: Non-lactose fermenter (colonies are pale colorless)b. Growth of Proteus on blood agar: observe the swarming and smell the fishy odorc. Biochemical tests for Proteus:• Indole: variable• Citrate: variable• TSI: K/A, G- H2S+• Motility test: motile• Urease test: positive