Administrative Office

22 South Market St., Ste. 6D
Frederick, MD 21701

Phone: 301-682-5683
Fax: 301-682-3499
Mobile Clinic Phone: 410-340-3791
Email: main@aMissionofMercy.org


Medical Team

Michael Sullivan, M.D. – Chief Medical Director
Roslyn Kellum, RN, DDS, Dental Director
Barbara Rebele, PA – Staff Clinician
Maureen Liddle, RN – Nursing Director
Errol Kellum, Dental Coordinator
Darren Guarino, Equipment Manager


Executive Administrative Staff

Linda Ryan
Executive Director

Jennifer White
Development Manager

Rachel Smith
Administrative Assistant