Tetraphase Pharmaceuticals, Inc. (NASDAQ:TTPH), a clinical-stage biopharmaceutical company developing novel antibiotics for serious and life-threatening multidrug-resistant (MDR) bacterial infections, today announced that it has been selected for addition to the NASDAQ Biotechnology Index® (Nasdaq:^NBI). The annual re-ranking of the NASDAQ Biotechnology Index will become effective upon market open on Monday, December 22, 2014. The NASDAQ Biotechnology Index is designed to track the performance of a set of securities listed on The NASDAQ Stock Market® (NASDAQ®) that are classified as either biotechnology or pharmaceutical according to the Industry Classification Benchmark (ICB). The NASDAQ Biotechnology Index is calculated under a modified capitalization-weighted methodology and ranked on annual basis. All securities in the NASDAQ Biotechnology Index are listed on the NASDAQ Global Market or the NASDAQ Global Select Market, and meet minimum market value and share volume requirements among other criteria. The NASDAQ Biotechnology Index is the basis for the iShares NASDAQ Biotechnology Index(SM) Fund. In addition, options based on the iShares NASDAQ Biotechnology Index Fund trade on various exchanges. For more information about the NASDAQ Biotechnology Index visit www.nasdaq.com. About Tetraphase Pharmaceuticals, Inc. Tetraphase is a clinical-stage biopharmaceutical company using its proprietary chemistry technology to create novel antibiotics for serious and life-threatening multidrug-resistant (MDR) bacterial infections, including many of the MDR Gram-negative bacteria highlighted as urgent public health threats by the Centers for Disease Control and Prevention (CDC). Tetraphase's lead product candidate, eravacycline, is a fully synthetic tetracycline derivative being developed as a broad-spectrum intravenous and oral antibiotic in the IGNITE program (Investigating Gram-negative Infections Treated with Eravacycline). Under this program, two Phase 3 clinical trials are ongoing: IGNITE 1 for the indication of complicated intra-abdominal infections (cIAI) and IGNITE 2 for complicated urinary tract infections (cUTI). Tetraphase has created more than 3,000 novel tetracycline analogs using its technology platform; in addition to eravacycline, Tetraphase has generated multiple preclinical antibiotic candidates that are currently being evaluated for clinical suitability. Please visit www.tphase.com for more company information. Forward-Looking Statements Any statements in this press release about our future expectations, plans and prospects, including statements regarding our strategy, future operations, prospects, plans and objectives, and other statements containing the words "anticipates," "believes," "expects," "plans," "will" and similar expressions, constitute forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including: whether our cash resources will be sufficient to fund our continuing operations for the period anticipated; whether results obtained in preclinical studies and early clinical trials will be indicative of results obtained in future clinical trials; whether eravacycline will advance through the clinical trial process on a timely basis and receive approval from the United States Food and Drug Administration or equivalent foreign regulatory agencies; whether, if eravacycline obtains approval, it will be successfully distributed and marketed; and other factors discussed in the "Risk Factors" section of our most recent quarterly report on Form 10-Q, filed with the Securities and Exchange Commission on November 10, 2014. In addition, the forward-looking statements included in this press release represent our views as of December 15, 2014. We anticipate that subsequent events and developments will cause our views to change. However, while we may elect to update these forward-looking statements at some point in the future, we specifically disclaim any obligation to do so.