Dr. Ivan, has proudly served the Greater Ocala community for more than 20 years. While not originally from Ocala, the community has become home in every meaningful sense, with nearly half his life dedicated to caring for patients and families throughout North Central Florida. His long-standing service reflects both clinical excellence and a deep commitment to the health of the region.

Dr. Ivan specializes in the diagnosis and management of complex infectious diseases in both inpatient and outpatient settings. Patients and referring physicians rely on his expertise in treating sepsis, bloodstream infections, osteomyelitis, endocarditis, multidrug-resistant infections, HIV, and complicated wound infections.

Throughout his career, Dr. Ivan has provided infectious disease consultation services at many of the region’s leading healthcare facilities, including AdventHealth Ocala, HCA Florida Ocala Hospital, Kindred Hospital Ocala, West Marion Community Hospital, and Encompass Health Rehabilitation Hospital of Ocala.

In addition to direct patient care, he has held numerous leadership positions focused on infection prevention, antimicrobial stewardship, and hospital quality initiatives, including:

Infection Control Director @ AdventHealth Ocala and HCA Florida Ocala Hospital

Antimicrobial Stewardship Program Leadership — AdventHealth Ocala and HCA Florida Ocala Hospital

Pharmacy & Therapeutics Committee Member — AdventHealth Ocala and HCA Florida Ocala Hospital

Former Chief of Medicine — AdventHealth Ocala (2023–2025)

Dr. Ivan also works closely with the AdventHealth Wound Care & Hyperbaric Center, helping manage complex diabetic, vascular, and chronic wound infections while supporting advanced wound healing therapies and hyperbaric medicine.

At his outpatient infectious disease clinic in Ocala, Dr. Ivan provides comprehensive infectious disease evaluations alongside advanced outpatient infusion and IV antibiotic therapy services. His state-of-the-art OPAT (Outpatient Parenteral Antimicrobial Therapy) program operates 7 days a week, allowing patients to safely receive hospital-level IV antibiotic treatment in a closely monitored outpatient setting. This approach promotes continuity of care, reduces hospital readmissions, and allows patients to receive specialized treatment close to home.

Recognized nationally for both clinical excellence and compassionate care, Dr. Ivan has received multiple America’s Top Physician, Patient’s Choice, and Most Compassionate Doctor honors. Patients value his calm, analytical approach, attention to detail, and commitment to clear, thoughtful communication.

Through decades of service, Dr. Ivan remains dedicated to advancing infectious disease care, improving patient outcomes, supporting referring providers, and strengthening infection prevention efforts throughout the Greater Ocala community.

RikkiLee McCroskey is a Florida native and board-certified Advanced Practice Registered Nurse with a diverse clinical background and a passion for caring for patients with complex medical needs. She began her nursing career after earning her RN in June 2013, later completing her Bachelor of Science in Nursing at Chamberlain College of Nursing in December 2016. She went on to obtain her Master of Science in Nursing from Chamberlain in August 2020.

Throughout her career, RikkiLee has built a strong foundation in high-acuity care. She previously served as a trauma nurse in the emergency department, where she developed the ability to think critically, act decisively, and remain steady in fast-paced situations. After becoming a nurse practitioner, she worked in primary care, further strengthening her skills in comprehensive, patient-centered management.

In 2022, RikkiLee found her professional home in infectious disease, where she is dedicated to supporting patients facing serious and often progressive illnesses. She is especially recognized for her ability to manage medically complex cases while maintaining a compassionate, steady presence.

Known for quickly building strong rapport with patients and their families, RikkiLee prioritizes trust, communication, and education. She believes these elements are essential to encouraging treatment adherence and achieving the best possible outcomes. Her approach blends clinical expertise with warmth, ensuring patients feel both confident in their care and genuinely supported.

Maria Shirley is a proud Ocala, Florida native and an Advanced Practice Registered Nurse with more than a decade of experience in high-acuity and critical care settings. She began her nursing career after graduating from nursing school in September 2013. Driven by a commitment to continued growth, Maria earned her Bachelor of Science in Nursing from Florida SouthWestern State College in July 2018 and completed her Master of Science in Nursing at South University in May 2025.

Before becoming a nurse practitioner, Maria built an extensive background as an ICU, cath lab, and trauma RN, gaining 11 years of hands-on critical care experience. These roles strengthened her ability to think analytically, respond quickly, and implement timely, appropriate interventions for patients with complex and rapidly changing conditions.

Maria is known for her collaborative approach and values strong teamwork in delivering safe, effective care. She works closely with multidisciplinary teams to ensure each patient’s needs are met while also providing education and counseling that empowers patients and families to take an active role in their health.

A dedicated and hardworking clinician, Maria is passionate about improving outcomes and enhancing the overall patient experience. Her leadership style is grounded in compassion, communication, and an unwavering commitment to providing best-in-class care.

Lauren Stringer is a nationally board-certified Family Nurse Practitioner with a strong foundation in medicine that began in 2008. Her clinical background spans high-acuity hospital care, regenerative medicine, aesthetics, and infectious disease, providing her with broad, well-rounded expertise and a deep understanding of complex patient needs. She holds national certification through the American Academy of Nurse Practitioners.

Lauren has trained alongside respected medical leaders across multiple specialties, allowing her to integrate advanced clinical knowledge with thoughtful, evidence-based care. Her practice philosophy emphasizes precision in diagnosis, individualized treatment planning, and staying current with emerging medical research to ensure the highest standards of care.

Widely recognized for her diagnostic acumen, strategic clinical thinking, and attention to detail, Lauren is committed to delivering patient-centered care that prioritizes safety, outcomes, and long-term wellness. She values education, clear communication, and collaborative decision-making as essential components of effective healthcare.

A lifelong Floridian with deep roots in Citrus County, Lauren is driven by a strong commitment to her community and a passion for helping patients achieve optimal health and quality of life.