Q: Which antibiotic can be used to counter cholestatic pruritus?

Answer: Rifampicin

Rifampicin can be used in the treatment of cholestatic pruritus. Actual mechanism of action is not very clear though.  First line therapy is generally cholestyramine, a bile acid sequestrant. But if needed Rifampicin can be used for patient's comfort.

Reference:

Hofmann, AF (2002). "Rifampicin and treatment of cholestatic pruritus". Gut 2002;50:436–9 51 (5): 756–757.