Healthcare firm Sam Brown Inc. is outside communications counsel to Tetraphase Pharmaceuticals as the Watertown, Mass.-based biotech company pursues an initial public offering worth up to $86.3M.

SBI, based in Wayne, Pa., is led by pharma PR vet Laura Liotta.

Tetraphase, which develops antibiotics for drug-resistant infections, filed for the IPO on Feb. 11. Its lead product candidate is eravacyclinem, which has wrapped a successful Phase 2 clinical trial. It expects data from a Phase 3 program, slated to begin in Q3 of 2013, by Q1 of 2015.

The company reported $4.3M in contract and grant revenue through the third quarter of 2012 for a net loss of $12M. It has raised about $60M in venture funding, according to CrunchBase.