content: <PAGE>
  
                         SECURITIES AND EXCHANGE COMMISSION
  
                               Washington, D.C. 20549
  
                                      FORM 8-K
  
                                   CURRENT REPORT
  
       Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
  
                                  October 24, 2001
                  ------------------------------------------------
                  Date of Report (Date of earliest event reported)
  
                                 -------------------
  
                            ESSENTIAL THERAPEUTICS, INC.
                 (formerly known as Microcide Pharmaceuticals, Inc.)
                 ---------------------------------------------------
                 (Exact Name of Registrant as Specified in Charter)
  
  
              DELAWARE                  0-28006                  94-3186021
  --------------------------------------------------------------------------------
  (State or Other Jurisdiction        (Commission              (IRS Employer
        of Incorporation)             File Number)          Identification No.)
  
  
                      1365 Main Street, Waltham, MA         02451
                 ---------------------------------------------------
                 (Address of Principal Executive Offices) (Zip Code)
  
                                   (781) 647-5554
                ----------------------------------------------------
                (Registrant's telephone number, including area code)
  
                                   ---------------
  
  <PAGE>
                                        -2-
  
  Item 2.  Acquisition or Disposition of Assets.
  
       On October 24, 2001, Essential Therapeutics, Inc., a Delaware corporation
  (formerly known as Microcide Pharmaceuticals, Inc.) completed its acquisition of
  The Althexis Company, Inc., a Delaware corporation ("Althexis") pursuant to
  terms of the Agreement and Plan of Merger, dated as of July 27, 2001 (the
  "Agreement"), by and among Essential Therapeutics, Althexis and California MP
  Acquisition Inc., a Delaware corporation, with Althexis surviving and becoming a
  wholly owned subsidiary of Essential Therapeutics.
  
       Upon the completion of the acquisition of Althexis, a total of 5,188,026
  shares of Essential Therapeutics common stock were issued in exchange for all of
  the outstanding capital stock of Althexis. In addition, Essential Therapeutics
  assumed all outstanding stock options and warrants of Althexis, which are
  presently exercisable for 362,169 shares of Essential Therapeutics common stock.
  In addition, Essential Therapeutics agreed to file a registration statement with
  the Securities and Exchange Commission to register the resale of Essential
  Therapeutics common stock acquired by the former Althexis stockholders.
  
  Items 5. Other Events.
  
       In connection with the acquisition of Althexis on October 24, 2001,
  Essential Therapeutics, Inc. also:
  
  o    completed an equity financing by way of a private placement of an aggregate
       of 60,000 shares of its Series B convertible redeemable preferred stock for
       a total purchase price of $60,000,000; and
  
  o    changed its name from Microcide Pharmaceuticals, Inc. to Essential
       Therapeutics to better reflect the business strategy and operations of the
       combined company resulting from the acquisition of Althexis.
  
       The 60,000 shares of Series B convertible redeemable preferred stock issued
  to the investors in the financing are initially convertible into an aggregate of
  approximately 20,000,000 shares of Essential Therapeutics common stock. In
  connection with the financing, Essential Therapeutics agreed to file a
  registration statement with the Securities and Exchange Commission to register
  the shares of Essential Therapeutics common stock that would be issued to the
  investors upon conversion of the Series B preferred stock.
  
       In connection with the acquisition and financing, Essential Therapeutics
  moved its headquarters and principal executive offices to 1365 Main Street,
  Waltham, MA 02451.
  
  <PAGE>
                                        -3-
  
  Item 7.  Financial Statements, Pro Forma Financial Information and Exhibits.
  
  (a)  Financial Statements of Business Acquired.
  
       Essential Therapeutics will file any financial information required by Item
       7(a) as promptly as practicable, but in any event prior to January 7, 2002.
  
  (b)  Pro Forma Financial Information.
  
       Essential Therapeutics will file any pro forma financial information
       required by Item 7(b) as promptly as practicable, but in any event prior to
       January 7, 2002.
  
  (c)  Exhibits.
  
  Exhibit
  Number            Description
  ------            -----------
  
  2.1  Agreement and Plan of Merger, dated July 27, 2001, by and among Essential
  Therapeutics, Inc. and The Althexis Company, Inc.
  
  3.1  Fourth Amended and Restated Certificate of Incorporation of Essential
  Therapeutics, Inc. (incorporated by reference to Exhibit No. 3.1 to the
  Registration Statement on Form S-1 (File No. 333-32206)).
  
  3.2  Certificate of Designations of Series B Convertible Redeemable Preferred
  Stock filed with the Secretary of the State of the State of Delaware on October
  24, 2001.
  
  3.3  Certificate of Amendment to the Company's Restated Certificate of
  Incorporation filed with the Secretary of the State of the State of Delaware on
  October 24, 2001.
  
  10.1 Form of Subscription Agreement, dated as of July 27, 2001, by and between
  Essential Therapeutics, Inc. and each purchaser of Series B Convertible
  Redeemable Preferred Stock.
  
  10.2 Form of Voting Agreement, dated as of October 24, 2001, by and between
  Essential Therapeutics, Inc. and each purchaser of Series B Convertible
  Redeemable Preferred Stock.
  
  99.1 Press release, dated October 25, 2001.
  
  <PAGE>
                                        -4-
  
                                     SIGNATURES
                                     ----------
  
       Pursuant to the requirements of the Securities Exchange Act of 1934, the
  Registrant has duly caused this report to be signed on its behalf by the
  undersigned hereunto duly authorized.
  
  Date: November 8, 2001            ESSENTIAL THERAPEUTICS, INC.
  
  
                                      By:  /s/ Mark Skaletsky
                                          ----------------------------------------
                                           Mark Skaletsky,
                                           President, Chief Executive Officer and
                                           Chairman of the Board of Directors
                                           (Principal Executive Officer)
  
  <PAGE>
                                        -5-
  
                                    Exhibit Index
  
  Exhibit
  Number            Description
  ------            -----------
  
  2.1  Agreement and Plan of Merger, dated July 27, 2001, by and among Essential
  Therapeutics, Inc. and The Althexis Company, Inc.
  
  3.1  Fourth Amended and Restated Certificate of Incorporation of Essential
  Therapeutics, Inc. (incorporated by reference to Exhibit No. 3.1 to the
  Registration Statement on Form S-1 (File No. 333-32206)).
  
  3.2  Certificate of Designations of Series B Convertible Redeemable Preferred
  Stock filed with the Secretary of the State of the State of Delaware on
  October 24, 2001.
  
  3.3  Certificate of Amendment to the Company's Restated Certificate of
  Incorporation filed with the Secretary of the State of the State of Delaware on
  October 24, 2001.
  
  10.1 Form of Subscription Agreement, dated as of July 27, 2001, by and between
  Essential Therapeutics, Inc. and each purchaser of Series B Convertible
  Redeemable Preferred Stock.
  
  10.2 Form of Voting Agreement, dated as of October 24, 2001, by and between
  Essential Therapeutics, Inc. and each purchaser of Series B Convertible
  Redeemable Preferred Stock.
  
  99.1 Press release, dated October 25, 2001.
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metadata_filer: {"company-data": {"conformed-name": "ESSENTIAL THERAPEUTICS INC", "cik": "0001010915", "assigned-sic": "2834", "irs-number": "943186021", "state-of-incorporation": "CA", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "000-28006", "film-number": "1778670"}, "business-address": {"street1": "850 MAUDE AVE", "city": "MOUNTAIN VIEW", "state": "CA", "zip": "94043", "phone": "4154281550"}, "mail-address": {"street1": "850 MAUDE AVE", "city": "MOUNTAIN VIEW", "state": "CA", "zip": "94043"}, "former-company": {"former-conformed-name": "MICROCIDE PHARMACEUTICALS INC", "date-changed": "19960319"}}
text: SECURITIES AND EXCHANGE COMMISSION
  
                               Washington, D.C. 20549
  
                                      FORM 8-K
  
                                   CURRENT REPORT
  
       Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
  
                                  October 24, 2001
                  ------------------------------------------------
                  Date of Report (Date of earliest event reported)
  
                                 -------------------
  
                            ESSENTIAL THERAPEUTICS, INC.
                 (formerly known as Microcide Pharmaceuticals, Inc.)
                 ---------------------------------------------------
                 (Exact Name of Registrant as Specified in Charter)
  
              DELAWARE                  0-28006                  94-3186021
  --------------------------------------------------------------------------------
  (State or Other Jurisdiction        (Commission              (IRS Employer
        of Incorporation)             File Number)          Identification No.)
  
                      1365 Main Street, Waltham, MA         02451
                 ---------------------------------------------------
                 (Address of Principal Executive Offices) (Zip Code)
  
                                   (781) 647-5554
                ----------------------------------------------------
                (Registrant's telephone number, including area code)
  
                                   ---------------
  -2-
  
  Item 2.  Acquisition or Disposition of Assets.
  
       On October 24, 2001, Essential Therapeutics, Inc., a Delaware corporation
  (formerly known as Microcide Pharmaceuticals, Inc.) completed its acquisition of
  The Althexis Company, Inc., a Delaware corporation ("Althexis") pursuant to
  terms of the Agreement and Plan of Merger, dated as of July 27, 2001 (the
  "Agreement"), by and among Essential Therapeutics, Althexis and California MP
  Acquisition Inc., a Delaware corporation, with Althexis surviving and becoming a
  wholly owned subsidiary of Essential Therapeutics.
  
       Upon the completion of the acquisition of Althexis, a total of 5,188,026
  shares of Essential Therapeutics common stock were issued in exchange for all of
  the outstanding capital stock of Althexis. In addition, Essential Therapeutics
  assumed all outstanding stock options and warrants of Althexis, which are
  presently exercisable for 362,169 shares of Essential Therapeutics common stock.
  In addition, Essential Therapeutics agreed to file a registration statement with
  the Securities and Exchange Commission to register the resale of Essential
  Therapeutics common stock acquired by the former Althexis stockholders.
  
  Items 5. Other Events.
  
       In connection with the acquisition of Althexis on October 24, 2001,
  Essential Therapeutics, Inc. also:
  
  o    completed an equity financing by way of a private placement of an aggregate
       of 60,000 shares of its Series B convertible redeemable preferred stock for
       a total purchase price of $60,000,000; and
  
  o    changed its name from Microcide Pharmaceuticals, Inc. to Essential
       Therapeutics to better reflect the business strategy and operations of the
       combined company resulting from the acquisition of Althexis.
  
       The 60,000 shares of Series B convertible redeemable preferred stock issued
  to the investors in the financing are initially convertible into an aggregate of
  approximately 20,000,000 shares of Essential Therapeutics common stock. In
  connection with the financing, Essential Therapeutics agreed to file a
  registration statement with the Securities and Exchange Commission to register
  the shares of Essential Therapeutics common stock that would be issued to the
  investors upon conversion of the Series B preferred stock.
  
       In connection with the acquisition and financing, Essential Therapeutics
  moved its headquarters and principal executive offices to 1365 Main Street,
  Waltham, MA 02451.
  -3-
  
  Item 7.  Financial Statements, Pro Forma Financial Information and Exhibits.
  
  (a)  Financial Statements of Business Acquired.
  
       Essential Therapeutics will file any financial information required by Item
       7(a) as promptly as practicable, but in any event prior to January 7, 2002.
  
  (b)  Pro Forma Financial Information.
  
       Essential Therapeutics will file any pro forma financial information
       required by Item 7(b) as promptly as practicable, but in any event prior to
       January 7, 2002.
  
  (c)  Exhibits.
  
  Exhibit
  Number            Description
  ------            -----------
  
  2.1  Agreement and Plan of Merger, dated July 27, 2001, by and among Essential
  Therapeutics, Inc. and The Althexis Company, Inc.
  
  3.1  Fourth Amended and Restated Certificate of Incorporation of Essential
  Therapeutics, Inc. (incorporated by reference to Exhibit No. 3.1 to the
  Registration Statement on Form S-1 (File No. 333-32206)).
  
  3.2  Certificate of Designations of Series B Convertible Redeemable Preferred
  Stock filed with the Secretary of the State of the State of Delaware on October
  24, 2001.
  
  3.3  Certificate of Amendment to the Company's Restated Certificate of
  Incorporation filed with the Secretary of the State of the State of Delaware on
  October 24, 2001.
  
  10.1 Form of Subscription Agreement, dated as of July 27, 2001, by and between
  Essential Therapeutics, Inc. and each purchaser of Series B Convertible
  Redeemable Preferred Stock.
  
  10.2 Form of Voting Agreement, dated as of October 24, 2001, by and between
  Essential Therapeutics, Inc. and each purchaser of Series B Convertible
  Redeemable Preferred Stock.
  
  99.1 Press release, dated October 25, 2001.
  -4-
  
                                     SIGNATURES
                                     ----------
  
       Pursuant to the requirements of the Securities Exchange Act of 1934, the
  Registrant has duly caused this report to be signed on its behalf by the
  undersigned hereunto duly authorized.
  
  Date: November 8, 2001            ESSENTIAL THERAPEUTICS, INC.
  
                                      By:  /s/ Mark Skaletsky
                                          ----------------------------------------
                                           Mark Skaletsky,
                                           President, Chief Executive Officer and
                                           Chairman of the Board of Directors
                                           (Principal Executive Officer)
  -5-
  
                                    Exhibit Index
  
  Exhibit
  Number            Description
  ------            -----------
  
  2.1  Agreement and Plan of Merger, dated July 27, 2001, by and among Essential
  Therapeutics, Inc. and The Althexis Company, Inc.
  
  3.1  Fourth Amended and Restated Certificate of Incorporation of Essential
  Therapeutics, Inc. (incorporated by reference to Exhibit No. 3.1 to the
  Registration Statement on Form S-1 (File No. 333-32206)).
  
  3.2  Certificate of Designations of Series B Convertible Redeemable Preferred
  Stock filed with the Secretary of the State of the State of Delaware on
  October 24, 2001.
  
  3.3  Certificate of Amendment to the Company's Restated Certificate of
  Incorporation filed with the Secretary of the State of the State of Delaware on
  October 24, 2001.
  
  10.1 Form of Subscription Agreement, dated as of July 27, 2001, by and between
  Essential Therapeutics, Inc. and each purchaser of Series B Convertible
  Redeemable Preferred Stock.
  
  10.2 Form of Voting Agreement, dated as of October 24, 2001, by and between
  Essential Therapeutics, Inc. and each purchaser of Series B Convertible
  Redeemable Preferred Stock.
  
  99.1 Press release, dated October 25, 2001.