Review Question - QID 211004

A 59-year-old man presents to the emergency department because of severe flank pain. He says that the pain came on suddenly while he was at home and is located on his right side. He also says that he has had fever and chills for the last 2 days, but he did not seek medical attention because he assumed that it was just a cold. His past medical history is significant for intermittent kidney stones, hypertension, peptic ulcer disease, and low back pain. He says that he takes vitamin supplements, antihypertensives, a proton pump inhibitor, and occasional over the counter pain medicine though he doesn't recall the names of these drugs. He also drinks socially with his friends but does not exceed 2 drinks per day. Physical exam reveals severe costovertebral angle tenderness as well as gross hematuria. A computed tomography scan is obtained showing ring shadows in the medullae of the right kidney. Which of the following most likely contributed to the development of this patient's condition?