Mission Viejo-based nursing home company Ensign Group Inc. and its joint venture have bought a franchiser of urgent care clinics.

Ensign and its joint venture, Phoenix-based Immediate Clinic LLC, bought Doctors Express Inc. of Baltimore for an undisclosed price.

Doctors Express, founded in 2005, has 49 walk-in, urgent care facilities. The company has awarded 143 franchises in 24 states; 85 of those will be operating by the end of 2012.

Ensign formed Immediate Clinic in January to expand its presence in urgent care. It’s working with John Shufelt, founder and former chief executive of Mesa, Ariz.-based NextCare Inc., on the venture.