**5.7** *E. coli* **on violet red bile agar**

Violet red bile agar (VRBA) is a selective medium used to detect and enumerate lactose-fermenting coliform. Lactose-fermenting microorganisms produce pink to red colonies that are generally surrounded by a reddish zone of precipitated bile. Bluish fluorescence is seen around colonies under UV [32] as shown in **Figure 9**.

#### **5.8** *E. coli* **on cystine lactose electrolyte-deficient agar**

It promotes the growth and enumeration of UTIs however due to a shortage of electrolytes; it prevents excessive swarming of *Proteus* species. On cystine lactose electrolyte-deficient (CLED) agar, lactose fermenters form yellow colonies, while non-lactose fermenters form blue colonies [33] as shown in **Figure 10**.

#### **Figure 9.**

*VRBA agar, A:* E. coli*, pinkish red with bile precipitate B: Salmonella gallinarium, fair to good growth; colorless colonies [32].*

**Figure 10.** *Growth of* E. coli *on cysteine lactose electrolyte-deficient agar, [34].*
