How Negative Is Culture-Negative Endocarditis in the Presence of a Pacemaker?

A case report of a 70-year-old man with pacemaker placed for atrial fibrillation in 1999 (generator change in 2016). His illness began 4 months earlier with "hots-and-colds" sensation for which he was admitted to an outside hospital and treated for community-acquired pneumonia for 7 days. Fevers persisted after discharge, and he received a 7-day doxycycline course 1 week later. Persistent fevers led to a second admission at the outside hospital. Infectious workup was negative but transesophageal echocardiography showed mass on pacemaker lead so he was transferred to our hospital. No mass on repeat transesophageal echocardiography (TEE) was seen, so he was discharged as culture-negative endocarditis on a 6-week course of vancomycin and ceftriaxone. New fevers after antibiotics led to another admission. He was found to have a high-grade methicillin-susceptible Staphylococcus aureus bacteremia at this time but still negative TEE. Pacemaker was empirically extracted and was found to be encased in thrombus. Intraoperative TEE with bubble study showed patent foramen ovale with left atrial clot. Lead/thrombus cultures were positive for methicillin-susceptible Staphylococcus aureus and were treated with oxacillin.