Rate and review Doctor Johnston on patientschoice.org. This physician has current office locations in Louisville, KY and has been practicing for over 27 years in their current profession. Post reviews on other Internists who you have had positive or negative office visit experiences with in the past. PCA empowers the patient with information to help you make a more informed decision when choosing a qualified doctor in your area. If you think you have an excellent Internist then show your appreciation and help nominate Doctor Johnston as a Patients' Choice Award winner.