Insights from a Rare Diagnostic Challenge: Brucella Endocarditis Involving a Cardiac Implantable Electronic Device

Abstract

Background and Purpose: Infective endocarditis (IE) in patients with previously implanted cardiac implantable electronic devices (CIEDs) is diagnostically challenging, particularly when consecutive cultures at different sites are negative. Blood culture–negative infective endocarditis (BCNIE) often results from atypical organisms, including Brucella in endemic areas—including the northern part of Iraq. We report a case of Brucella endocarditis involving a pacemaker lead, where lack of response to conventional antibiotics raised suspicion for zoonotic infection.

Methods: An 87-year-old male with hypertension, atrial fibrillation, and complete heart block (pacemaker-dependent for >3 years) presented with 20 days of undulant fever, night sweats, and chest discomfort. He was initially managed elsewhere as acute cholecystitis and received empiric antibiotics, but his fever persisted despite treatment. On admission, clinical examination revealed a pansystolic murmur, raised JVP, and peripheral edema. Echocardiography showed LV systolic dysfunction (EF 46%), moderate TR with moderate pulmonary hypertension, mean PAP = 45 mmHg, and a 2.5 × 2.3 cm mobile mass noted on the pacemaker lead. Multiple blood cultures were negative. Because of the patient’s persistent fever unresponsive to antibiotics, endemic exposure, and negative cultures, Brucella infection was strongly suspected. Serological testing confirmed Brucella endocarditis.

Results: The patient was initially treated with ceftriaxone and vancomycin for tricuspid IE. After confirmation of brucellosis, Targeted therapy was switched to gentamicin (10 days), doxycycline (12 weeks), and rifampicin (12 weeks). He improved clinically with resolution of fever and stabilization of cardiac function. Device extraction was considered but deferred given advanced age, comorbidities, and good clinical response.

Conclusions: This case underscores the importance of considering Brucella in BCNIE, particularly in endemic regions. Failure to respond to empirical antibiotics should prompt suspicion of atypical pathogens. Serological testing combined with echocardiography enables timely diagnosis, and targeted antimicrobial therapy can achieve favorable outcomes even in elderly, high-risk patients with device-related IE.