A Case of Complicated Bacteremia: When the Source Is in the Blood.

Infective endocarditis is an infectious disease of the heart tissue, mainly affecting heart valves and intracardiac devices. We present the case of a 71-year-old male pacemaker carrier with a history of hepatic cirrhosis, esophageal varices, hepatocellular carcinoma, and severe aortic stenosis, who was admitted to the emergency room and hospitalized due to upper gastrointestinal bleeding. Although upper endoscopy showed no signs of active acute hemorrhage, the patient required a red blood cell transfusion. Upon admission, elevated inflammatory parameters prompted the initiation of empirical therapy with ceftriaxone. Although urinalysis, chest X-ray, thoracoabdominopelvic computed tomography, and transthoracic echocardiogram weren't suggestive of infection, an was isolated in blood cultures. Following an antibiotic switch to daptomycin, based on susceptibility testing, and the patient's hemodynamic stability, he was transferred to a home hospitalization unit for continued care. Despite good clinical and analytical progress, the patient's history of aortic valve stenosis and pacemaker, along with persistently positive blood cultures despite antibiotic therapy and sustained fever, raised a high level of clinical suspicion. This led to the decision to perform a new echocardiogram, which revealed several aortic valve vegetations, allowing the diagnosis of infective endocarditis. Following a multidisciplinary discussion, and in accordance with antibiotic susceptibility tests, linezolid was initiated. After 40 days, although the echocardiogram was still suggestive of aortic valve infiltration due to an infectious process, hemodynamic stability, sustained apyrexia, and sterile blood cultures allowed for a possible discharge on oral therapy with moxifloxacin and rifampicin. Although this is a case of infective endocarditis in a high-risk patient, the chronology is unusual, as endocarditis was not detected in the initial echocardiogram. The diagnosis was only possible after weeks of persistent positive blood cultures, thanks to the medical team's high level of suspicion, which led them to insist on repeating the echocardiogram. In fact, the diagnosis of infective endocarditis remains a challenge to this day. This case highlights the importance of recognizing risk factors and pursuing the diagnosis when clinical suspicion persists, including repeating imaging when necessary to ensure timely diagnosis and appropriate management.