David Altarac has been appointed chief medical officer of Entasis Therapeutics (NASDAQ: ETTX). He will succeed Robin Isaacs, who will retire from the Waltham, MA-based company at the end of the year. Entasis said Isaacs will continue to serve as an advisor. Altarac’s experience includes senior roles at Shire, NeoStem, and Merck (NYSE: MRK). Entasis, an AstraZeneca (NYSE: AZN) spinout, is developing antibacterial products for infections caused by drug-resistant bacteria.