Physicians are the cornerstone of medicine, which is why we employ only the most skilled and experienced doctors. Our physicians set the standard for quality and care, we encourage you to get to know them better by reading a little about each practitioner below.


Salvador J. Abrams, MD FACEP
Medical Director

Born in Chicago, Illinois, Dr. Abrams grew up in Mexico City, where he attended school and obtain his medical degree from the UNAM (National Autonomous University of Mexico). After graduating, he returned to his native Chicago, where he completed his post graduate training at Swedish Covenant Hospital/Rush Presbyterian St. Luke’s Hospital. He obtained his board certification in emergency medicine since 1993, and spent the first part of his career as the medical director of the Emergency Department at Alexian Brothers Medical Center in Elk Grove Village, Illinois. In addition, he was the president of Emergency and Ambulatory Care Consultants, providing staffing to several hospitals in the Chicago area.

Dr. Abrams moved to San Antonio in 2001, where he joined Edcare Management/Hospital Physician Partners, becoming the medical director of the emergency department at southwest general hospital in San Antonio, as well as regional medical director for the company, supervising medical care in over 10 emergency departments. He joined Arete medical group in 2010, serving as medical director/chief medical officer of our clinics. Dr. Abrams brings experience and leadership to our new emergency clinic. Focused on providing excellent medical care and customer service, he says that “we should treat patients as if they were members of our own family”.

Doctor Gonzales

Robert M. Gonzalez, MD

Dr Gonzalez is a Board Certified, residency trained, Emergency Medicine Physician. He brings 20 years of Emergency Medicine experience to the Schertz-Cibolo Emergency Clinic. He completed his undergraduate degree at  Abilene Christian University; medical school at the University of Illinois College of Medicine; and  his Emergency Medicine  specialty training at Maricopa Medical Center, a  level one trauma and regional burn center in Phoenix, AZ. He began his practice in San Antonio, TX in 1997 with the Baptist Health system. In 2006 he transferred to the Seton Health System in Austin, TX;  where in addition to his clinical duties as an attending physician in the ER, he served as Chief of Staff at Seton Southwest Hospital..The Gonzalez family has a special connection with Schertz-Cibolo area, as their son graduated from Samuel Clemens High School. They reside in the Garden Ridge area where they dabble in their favorite hobbies which are beekeeping and dog sport. He and his wife, Nancy,  are very happy to be back, closer to family and friends.




Dr. MacGillivray

Dr. MacGillivray is a California native raised in both Los Angeles and Del Rio, Texas. He received his undergraduate degree in Zoology in 1992 from the University of California at Davis and attended medical school at the University of Kansas, School of Medicine, in Kansas City. Dr. MacGillivray subsequently finished his Family Medicine residency training as Chief Resident at The University of Kansas Medical Center. He is currently board certified in Family Medicine.

During the last ten years, Dr. MacGillivray has actively practiced in a wide spectrum of Family Medicine including outpatient and inpatient medicine, Occupational Medicine, Emergency Medicine, Obstetrics and Pediatrics. His experience allows him to incorporate a comprehensive approach to the care of his patients through all stages of their lifespan.




Dr. Tellez Florez
Dr. Tellez Flores graduated from Family Medicine Residency at Henry Ford Health System in Detroit Michigan in 2013. During his 3 years of training, he liked the fast pace in the Emergency Department, doing his last two years of training mainly in the ED. After completing his residency he completed one more year of fellowship in Emergency Medicine in Ohio. He graduated 2014 and since then he has been practicing Emergency Medicine.

“Emergency Medicine appeals to me as a humanistic, challenging field, offering the opportunity to provide immediate help to people in the most vital aspect of their lives: their health.”






Dr. Castillo











Doctor Altamirano

Dr. Altarimano
Dr. Ray Altamirano  is a local native, proudly born and raised in San Antonio, Texas. After graduating as valedictorian from his high school, he attended Texas A&M University in College Station and received his undergraduate degree in Biology in 2002. He then attended medical school at Universidad Autonoma de Guadalajara and New York Medical College. Dr. Altamirano subsequently finished his Family Medicine residency training as Chief Resident at Conroe Family Practice Residency Program. He is currently board certified in Family Medicine.

Dr. Altamirano has engaged in a multitude of medical scopes including community outpatient medicine, inpatient medicine, and emergency medicine. Recognizing that the practice of medicine is an art and not absolute; it is being familiar with all aspects of the health system that allows Dr. Altamirano to be practical and comprehensive in his approach to his patients.

Dr. Altamirano is married with 4 children. He is an avid Spurs and Aggies sports fan. He enjoys traveling, painting, and playing poker in his spare time.

Dr. John Rayfield

John Rayfield, MD is a staff physician at the Schertz/Cibolo Emergency Clinic. He is Board Certified in Emergency Medicine and has 20 years of experience as a doctor.
Dr Rayfield retired from the Army as a Lieutenant Colonel in 2013 after 20 years of service. He enjoyed operational medicine and spent the majority of his career assigned to troop units. He has almost 3 years of combat time in Iraq and Afghanistan serving with the 24th Infantry Division, 1st Cavalry Division and US Special Operations Command in addition to a tour as a United Nations Peacekeeper in Macedonia while assigned to the 1st Armored Division. One of the many highlights of his career was being the recipient of the Spurgeon Neel Award, given annually to the top US Army Flight Surgeon for 2004. The latter part of his career was devoted to teaching and his last assignment was at the San Antonio Military Medical Center (SAMMC) as one of the Program Directors for the Emergency Medicine residency.
Dr Rayfield graduated from the United States Military Academy at West Point, then earned his medical degree from the Uniformed Services University of the Health Sciences in Bethesda, Maryland. He completed internship and Emergency Medicine residency training at SAMMC, serving as a Chief Resident during his senior year.
It is a pleasure to be part of an outstanding group of healthcare professionals here in Schertz and looking forward to being of service to the community.

William Gibson MD

Dr. Gibson is residency trained in Emergency Medicine and Pediatrics. He is board certified by the American Board of Emergency Medicine. Dr. Gibson is an honorably retired officer for the United States Air Force having spent over 23 years active duty. While a member of the military, Dr. Gibson served as a Flight Surgeon as well as pediatrician and emergency medicine physician with numerous deployments and significant leadership positions. These include the Associate Program Director for the San Antonio Joint Air Force and Army Emergency Medicine Residency program at Brooke Army Medical Center. After his retirement, he served as Assistant Professor and Pediatric Emergency Medicine Consultant at the University of Texas Health Science Center in San Antonio. Dr. Gibson is the author of multiple publications in the medical literature. He has also given local, regional and national lectures including to the national meeting of the Society of Academic Emergency Medicine. Dr. Gibson is married with two adult children. His daughter is a world-class swimmer who represented the United States at the 2017 World Aquatics Championships. Her accolades include being named to the NCAA Today’s Top Ten Athlete Scholars in 2018. His son is both a student and a leader of the Georgia Institute of Technology Robojackets team which competes nationally in robotics competitions. Honorably Discharged from USAF effective 1 July 2006