Rib-X Pharmaceuticals Appoints New Chair of Board of Directors

  Rib-X Pharmaceuticals Appoints New Chair of Board of Directors

—Accomplished Executive, Mary Szela, Brings 25 Years of Pharmaceutical Product
                                 Experience—

Business Wire

NEW HAVEN, Conn. -- January 4, 2013

Rib-X Pharmaceuticals, Inc. announced today that Mary Szela has been appointed
to its Board of Directors as its Chair. Ms. Szela brings her 25-year career as
an accomplished pharmaceutical executive to this leadership role.

"Mary Szela brings a wealth of talent and expertise to our team and is an
outstanding choice to lead our Board of Directors,” said Mark Leuchtenberger,
Chief Executive Officer of Rib-X. “Her broad commercial leadership experience
will be particularly valuable as we continue to advance development of an
urgently needed new antibiotic treatment option to patients and begin to
consider options for launching the product. We look forward to working closely
with Ms. Szela as we enter this exciting phase as a company and move ahead
with our plans to initiate the Phase 3 program for delafloxacin for the
treatment of acute bacterial skin and skin structure infections.”

With more than two decades in senior roles at Abbott Laboratories, Ms. Szela
most recently served as Senior Vice President, Global Strategic Marketing and
Services of the Pharmaceutical Products Group. Previously, she served as
Senior Vice President of U.S. Pharmaceuticals, an $8 billion business. For
over seven years, she directed the development, launch and growth of eight new
pharmaceutical products, including leadership of Abbott’s flagship product,
Humira.

Prior to 2001, Ms. Szela held a series of senior positions in Abbott’s
hospital products division where she was responsible for the peri-operative,
intensive care and pain management pharmaceutical business, the global
One-2-One outsourcing business, the critical care device business and the
vascular medicine pharmaceutical business.

About Rib-X:

Rib-X Pharmaceuticals, Inc. is a biopharmaceutical company developing new
antibiotics to provide superior coverage, safety and convenience for the
treatment of serious and life-threatening infections. The Company's
proprietary drug discovery platform provides an atomic-level,
three-dimensional understanding of interactions between drug candidates and
their bacterial targets and enables design of antibiotics with enhanced
characteristics. Rib-X has two antibiotic candidates in clinical development.
Delafloxacin is an enhanced spectrum IV/oral antibiotic intended for use as
first-line monotherapy primarily in hospitals and recently completed a Phase
2b clinical trial for the treatment of acute bacterial skin and skin structure
infections. Radezolid is a next-generation IV/oral oxazolidinone designed to
be a potent antibiotic with a safety profile permitting long-term treatment of
resistant infections. The Company's pipeline also includes its preclinical
RX-04 program, partnered with Sanofi, S.A., and other discovery stage
anti-infective programs. For more information, please visit www.rib-x.com.

Contact:

Company
Bob Conerly, 203-624-5606
bconerly@rib-x.com
or
Media Relations
Kari Watson, 781-235-3060
kwatson@macbiocom.com