BY SHEFAA EL ASTAL ID 220052425 Supervisedby Dr

BY : SHEFAA EL ASTAL ID : 220052425 Supervisedby: Dr. Abdelraouf A. Elmanama

Introduction Urea is a waste product of protein digestion in most vertebrates is excreted in the urine. Presence of the enzyme urease , which liberates ammonia from urea , is a useful diagnostic test for identifying bacteria.

Introduction Urea agar contains peptone, glucose , urea, and phenol red. p. H of the prepared medium is 6. 8(phenol red turns yellow ) . During incubation , bacteria possessing urease will produce ammonia that raise the p. H of the medium , turning the indicator fuchsia (hot pink) at p. H 8. 4.

Urease Test Urease, an enzyme produced by some microorganisms, attacks the nitrogen and carbon bond in amide compounds and forms the alkaline end product ammonia.

Significance The urease test is particularly helpful in identifying Proteus from other species to due to the rapid action of the enzyme by Proteus compared to other nonlactose fermenting enterics. The p. H indicator phenol red changes to a deep pink color in the present of the alkaline ammonia.

Proteus * gram (-ve) bacilli * (+ve) glucose fermentation *(-ve) oxidase test *(-ve) lactose fermentation *(+ve) urease test

Proteus

Salmonella *Gram (-)bacilli *(+ve) glucose fermentation *(-ve) oxidase test *(-ve) lactose fermentation *(-ve)urease test *motile

Salmonella infection Salmonella enteica

Shigella *Gram (-)bacilli *(+ve) glucose fermentation *(-ve) oxidase test *(-ve) lactose fermentation *(-ve)urease test *(-ve) motile Shigella grow on XLD agar

Procedure n n 1 -streak the slant of christensen s urea medium with the test organism. 2 -incubate at 35 C (or the appropriate temperature for the organism) for 24 hours to four days.

Result Positive: A bright pink with proteus , and some citrobacter species Negative : No charge with salmonella and shigella species

The tube on the left is a positive reaction, the tube in the middle is a negative reaction and the tube on the right in an un-inoculated control.

Urease test for the differentiation of T. mentagrophytes var. interdigitale [+7 days] from T. rubrum. [-7 days]

Urease test Urea Agar

Control and positive urease test

Urease Test *Strong Urease production *Uninoculated Tube *Negative Urease production