About
Hamidreza Khonsari, MD
Board-certified family physician serving Antioch and the East Bay since 1998.
Dr. Khonsari is a board-certified family physician. He graduated from Ross University School of Medicine in June of 1984 and completed his residency at Jamaica Hospital in New York in 1988, where he was chief resident in his final year.
After residency, Dr. Khonsari served as an attending family practice physician at Jamaica Hospital and acting director of the Family Practice Program. From 1989 to 1998, he worked as a family practice physician for Humana in Tampa, Florida and was a clinical preceptor for the University of South Florida's medical school.
In 1998, Dr. Khonsari opened his private practice in Antioch, California and incorporated it in 2005. He provides health care for men, women, and children of all ages, and is a certified advanced wound care management and hyperbaric oxygen specialist — treating complex wounds at Sutter Delta Hospital on a weekly basis.
Career
A career devoted to family medicine.
1984
Graduated from Ross University School of Medicine
1988
Completed residency at Jamaica Hospital, NY — chief resident in his final year
1989–1998
Family physician at Humana in Tampa, FL & clinical preceptor at the University of South Florida
1998
Opened private practice in Antioch, California
1999–2010
Director of Employee Health, Sutter Delta Medical Center
2005
Incorporated his private practice
2014
Named Primary Care Physician of the Year in the Sutter Network (5,000+ physicians)
Recognition
In 2014, Dr. Khonsari was recognized as Primary Care Physician of the Year among more than 5,000 physicians in the Sutter Network — a reflection of his patient-centered approach and clinical excellence.
Community service
Dr. Khonsari serves as the volunteer medical director at RotaCare, a free medical clinic in Pittsburg, CA, caring for low-income uninsured patients. He also serves on the board of Families Without Borders, a non-profit serving communities in West Africa.
Education
Medical School
Ross University, School of Medicine — Roseau, Dominica
Internship
Jamaica Hospital Medical Center — Richmond Hill, NY
Residency
Jamaica Hospital Medical Center — Richmond Hill, NY
Hospital affiliations
- Sutter Delta Medical Center — Antioch
- John Muir Health — Walnut Creek Medical Center
- John Muir Health — Concord Medical Center
Our care team
Dr. Khonsari is supported by two experienced physician assistants who help provide attentive, accessible care to every patient who walks through our doors.
Physician Assistant
Charmaine Santos, PA
Charmaine Santos is a board-certified Physician Assistant who completed her training at Samuel Merritt University after receiving her undergraduate degree in Biology with a molecular emphasis from the University of San Francisco in 2016. During her time at the University of San Francisco, she volunteered at a homeless clinic and conducted research in radiology at the San Francisco VA Medical Center. She also has prior experience as a hemodialysis technician and as a medical scribe prior to joining Bass Medical Group.
Charmaine currently works in Antioch providing primary care services. She chose to become a primary care provider because of her passion for preventive medicine. She believes that patient education is one of her most important duties as a provider and emphasizes shared decision-making. Using a patient-centered approach to medicine, her goal is to empower patients and support them to make the best-informed decisions for themselves and their health goals.
Charmaine is a Bay Area native and loves cheering on Bay Area sports teams. In her free time, Charmaine enjoys hiking, trying new foods, traveling, and spending time with loved ones.
Physician Assistant
Katherine De Castro, PA
Born and raised in the Bay Area, Katherine is a board-certified Physician Assistant (PA) who has always been deeply connected to her community and passionate about serving others. Her path to becoming a PA was shaped by a diverse background in healthcare, including work as a medical scribe and health coach in the emergency department, physical therapy aide, and behavioral technician. These roles gave her a broad perspective on patient care and highlighted the importance of strong provider-patient relationships. In addition to her clinical experience, Katherine has been actively involved in community health, including volunteering at the Alameda County Food Bank, teaching nutrition to elementary school students, and participating in medical outreach trips to Guatemala and the Philippines. These opportunities deepened her commitment to promoting health equity and serving underserved populations.
She completed her PA training at Bay Path University, where she developed a strong foundation in evidence-based medicine and compassionate care. Her experiences across various healthcare settings inspired her to pursue a career in primary care, where she could build long-term relationships with patients and focus on prevention, wellness, and continuity of care.
Outside of work, Katherine enjoys film photography, traveling to new places, reading, and spending quality time with her friends, family, and two beloved dogs. She is excited to bring her diverse experience and patient-centered approach to the primary care setting, where she is committed to supporting individuals and families in achieving their health goals.