Our Staff

Dr. Leslie Schmitz, DO


After graduating with high honors from St. Xavier University’s Pre-Med program, Dr. Leslie Schmitz earned her Medical degree and served her Internship at Chicago College of Osteopathic Medicine. She served her residency in Illinois at Evanston Northwestern Hospital where, recognizing her leadership skills, she was installed as Chief Medical Resident in her final year.

While waiting for her commencement of a Nephrology Fellowship at St. Louis University she practiced Internal Medicine as a Hospitalist in Lihue, Hawaii. As a Nephrology fellow, again cited for her leadership, was named Chief Nephrology Fellow for the last year of her tenure.
Upon completion of her Fellowship and after successfully passing her Board exams she practiced Nephrology for five years working with leading Nephrologists in Illinois and Indiana. She is board certified in Nephrology.

In December 2012, she joined with her friend and fellow Nephrologist, Dr. Margaret Quate in forming the partnership of Kidney Care of Michiana, a thriving practice here in Mishawaka, Indiana.

In her leisure time she cherishes time spent with her family, looks forward to travel and enjoys working out at the gym, swimming and gardening.

Dr. Margaret Quate-Operacz, MD


Dr. Margaret Quate (Peggy) combines a high degree of medical skills with great communication skills. She graduated with high honors from the University of Toledo. From there she attended the University of Cincinnati for seven years completing her Medical Degree, Internal Medicine Residency and a Fellowship in Nephrology. She is Board Certified in both fields.

She has been practicing Nephrology and Internal Medicine for over 6 years since the completion of her training. Since December 2012, she has partnered with her friend and fellow Nephrologist, Dr. Leslie Schmitz to form Kidney Care of Michiana, a growing practice here in Mishawaka. She believes strongly in providing the best and most up to date quality care to her patients. Good communication and close attention to detail are things she strives for.

Peggy is married with three children. What free time she has, she enjoys spending time with her family. She loves to travel and exercise.



Sarah Bortone, NP

Sarah S. Bortone, RN, MSN, FNP-BC graduated from the University of Indianapolis with a Bachelor of Science in Chemistry and Biology. Wanting to enter the medical field, she then earned her Bachelor of Science in Nursing from the Indiana University South Bend and then proceeded to graduate with her Masters of Science in Nursing degree from Indiana University of South Bend. Prior to joining Kidney Care of Michiana, Sarah worked at Mishawaka Orthopedics and was on staff at St. Joseph Regional Medical Center as an R.N. She began her career as a Nurse Practitioner with Decatur Vein Clinic. Sarah believes strongly in holistic, compassionate care for her patients and strives to achieve this.

Sarah is a mother of two children. She enjoys spending time with her family, traveling, exercising and the outdoors.

Joseph Muriithi, NP

Joseph Muriithi is a Board Certified Adult Acute Care Nurse Practitioner (ACNPC-AG) and licensed in the State of Indiana. He originally attended Goshen College, In Goshen Indiana where he received a Bachelor of Science in Nursing Degree in 2012. While working in Acute Care Dialysis as Registered Dialysis Nurse (RN) covering the four major hospitals in Michiana. Joseph then continued to pursue his interest in nursing, graduating with honors, from Walden University with a Master's of Science in Nursing. 

He believes in forging relationships with people to understand their health needs and goals and working collaboratively with each individual to develop a working plan to achieve their best possible state of health. 

Joseph is an active member of the American Association of Nurse Practitioners, the American Association of Critical Care Nurses and American Nephrology Nurses Association. 

In his free time, he enjoys spending time with his wife and their three children. He is an avid fan of Notre Dame Football, the Chelsea Soccer Club (UK) and the Chicago Bears.