EXHIBIT 23.1

               CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS

     We consent to the incorporation by reference in the Registration Statement
(Form S-8) pertaining to the Essential Therapeutics, Inc. 1996 Employee Stock
Purchase Plan of our report dated February 2, 2001, with respect to the
financial statements of Essential Therapeutics, Inc. (formerly Microcide
Pharmaceuticals, Inc.) included in its Annual Report (Form 10-K/A) for the year
ended December 31, 2000, filed with the Securities and Exchange Commission.

                                            /s/ ERNST & YOUNG LLP

Palo Alto, California
October 26, 2001