A Diagnostic Challenge Involving Enterococcus faecalis Bacteremia: A Case Report.

Enterococcus faecalis bacteremia presents a diagnostic challenge, particularly in elderly patients with multiple comorbidities and cardiac implantable electronic devices. We present the case of an 88-year-old woman with atrial fibrillation on anticoagulation, pacemaker placement, hypertension, hypothyroidism, and anxiety who presented with five days of abdominal pain, nausea, vomiting, and upper back/right shoulder pain. Initial evaluation raised concern for pneumonia due to the patient's chest X-ray and elevated temperature, and she was admitted for further management. Blood cultures at 48 hours grew Gram-positive cocci in pairs and chains and Enterococcus faecalis, prompting treatment with ceftriaxone and ampicillin and an extensive search for an infectious source. Transthoracic and transesophageal echocardiography showed no evidence of infective endocarditis or pacemaker-associated infection. Abdominal imaging was unrevealing. During hospitalization, the patient developed a declining hemoglobin and reported melena, prompting gastrointestinal evaluation. Colonoscopy revealed multiple colonic polyps, including tubular adenomas in the cecum and rectum, without evidence of malignancy. These adenomas were considered the most plausible portal of entry for bacteremia. Repeat blood cultures cleared, and the patient was transitioned to oral amoxicillin on discharge with outpatient follow-up. This case highlights the importance of considering gastrointestinal sources, including colorectal neoplasia, in patients with E. faecalis bacteremia of unclear origin. It also supports the role of multidisciplinary evaluation, including infectious disease, cardiology, and gastroenterology, in guiding workup and management.