Dr. Steven A. “Steve” Geller, a Howard County internist and medical director of the Centennial Medical Group in Columbia, died of undetermined causes Aug. 6 at Johns Hopkins Howard County Medical Center. The Pikesville resident was 65.

“Steve had a passion for primary care medicine and he believed in taking care of the whole patient and this led him to primary care rather than a specialization,” said Connor J. Ferguson, CEO of Centennial Medical Group. “He was always delivering high-level primary care to his patients.”

The son of Louis Geller, a chemist, and Bernice Geller, a teacher, Steven Andrew Geller was born and raised in the Bronx, New York, where he graduated from the Bronx High School of Science.

He earned a bachelor’s degree from Union College in Schenectady, New York, and his medical degree from the Johns Hopkins University School of Medicine.

He completed his residency at Hopkins and earned a fellowship at the American College of Physicians.

“He graduated at the top of his class at Hopkins and was positively brilliant,” Mr. Ferguson said.

Dr. Geller joined what was then the Howard County General Hospital — now Johns Hopkins Howard County Medical Center — where he rose to become president of its professional staff.

“His leadership, expertise and unwavering commitment to patient care were truly exemplary,” according to a statement announcing his death from the hospital.

Dr. Geller joined several predecessors of what became Centennial Medical Group in 2001, according to Mr. Ferguson, where he was medical director.

“His research gave him the opportunity to stay on the cutting edge of medicine and as new pharmaceutical opportunities came to market, he was able to help improve the health care of his patients. He would be doing principal research on 14 studies at a time,” Mr. Ferguson said.

“He was recognized in his practice for keeping people out of the hospital and he improved the quality of life for his patients,” he said. “He clearly had a tremendous ability in communicating with his patients and he did it in a most humble manner. His answers always provided a great deal of comfort and you could tell that medicine was truly his passion.”

Mr. Ferguson added: “He took care of people 365 days a year — that was part of his DNA — he wanted to give back to his patients. He lived health care every day. He practiced in Howard County for 36 years and his work ethic was unmatched.”

Dr. Geller had not retired at his death.

He enjoyed fishing, playing tennis and spending time with his grandchildren. He was a member of Har Sinai-Oheb Shalom Congregation.

Funeral services were held Aug. 8 at Sol Levinson & Bros. in Pikesville.

Dr. Geller is survived by his wife of 39 years, Beth Cohen, a pharmacist; three daughters, Dr. Kaitlin Baron, of Silver Spring, Meredith Zuckerman, of Catonsville, and Erin Stafford, of Miami; a brother, Dr. Robert Geller, of Atlanta; and four grandchildren.