Question

A 25-year-old female complained of burning on urination. The urine culture grew a clear colony on MacConkey agar. Biochemical testing revealed the following: TSI A/A H2S 37.C SIM +/+/+ 25.C SIM +/+/+ Citrate - Urea - MR/VP +/-ONPG PAD + Arginine - Lysine - Ornithine. This organism will also need to be serotyped. swarm. exhibit multiple antibiotic resistance, appear as a mucold colony.

Answer 1

The 25 years old female complaints of burning sensation on urination. So most probably the diagnosis is Urinary tract infection (UTI).
Now the causative organism grow on the MacConkey agar. So the most common organisms can be E.coli, Klebsiella, proteus.
Since the colony is clear in MacConkey agar so it is lactose non fermenter (pink if lactose fermenter). So it can be Proteus.

E. coli and Klebsiella both don't produce H2S. In case of E. coli urease should be negative, ONPG + in some cases. And in case of Klebsiella Citrate, urease and VP tests should be positive; MR should be negative. So these two organisms are ruled out.

But in Proteus sp. In TSI H2S is produced, citrate +/- , Urease +, MR/VP +/- , ONPG -.

Most of the test confirms that it is Proteus species (P. vulgaris/ P. mirabilis).

Since it's motile and has ability to swarm. So option 2nd swarming .