Contract research organization Chiltern, which is based in Wilmington and London, is expanding its footprint globally with a deal to buy Theorem Clinical Research.

Financial terms weren’t disclosed. The deal was announced early Wednesday.

Chiltern will grow to 3,700 from 2,200 employees with the deal and offer service in more than 45 countries.

It’s the third acquisition for Chiltern in two years. In 2014, Chiltern bought Cary-based Ockham and Pacific Clinical Research.

Chiltern is part of the growing CRO industry in North Carolina, and the deal reflects a continuing global acquisition spree or partnership agreements, such as recent ones made by Burlington-based LabCorp and Durham-based Quintiles (a with joint venture with Quest)

“This is a direct response to client demand for a clinical research partner that can provide scientific and operating strengths globally, in a responsive and flexible way,” said Dr. Jim Esinhart, Chiltern’sCEO. “This transaction will bring together more than 3,700 people in more than 45 countries dedicated to the philosophy of Designed Around You [Chiltern’s marketing slogan].”

The combined firm will keep the Chiltern name.

“Chiltern and Theorem have carved out complementary niches, even across key geographies,” said Dr. John Potthoff, Theorem’s CEO. “In key areas, our capabilities will dovetail into current Chiltern operations — this is a mutually beneficial deal.”

Ciltern says the deal will expand its reach not only physically (Japan, China) but also add more service offerings (medical devices and diagnostics, clinical analytics and clinical supplies.)

The deal is expected to close in the near future.