Tricuspid valve infective endocarditis due to ESBL producing E.coli associated with AV block requiring epicardial pacing: A case report

BACKGROUND: Infective endocarditis (IE) caused by non-HACEK gram-negative organisms accounts for fewer than 2% of cases, and endocarditis due to extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is rare. Right-sided involvement, particularly isolated tricuspid valve infective endocarditis (TVIE), and associated atrioventricular (AV) conduction abnormalities are rarely reported, creating diagnostic and management challenges, especially when pacing is required. CASE PRESENTATION: A 75-year-old Caucasian man with pre-existing right bundle branch block presented with syncope one week after hospitalization for ESBL E. coli bacteremia treated with intravenous ertapenem. Electrocardiography now revealed progressive AV conduction delay with intermittent high-degree AV block. Transthoracic echocardiography was nondiagnostic, while transesophageal echocardiography identified a tricuspid valve vegetation without abscess despite antimicrobial therapy. Progressive high-grade AV block developed despite appropriate antimicrobial therapy, necessitated urgent epicardial pacing due to contraindication of transvenous systems in active infection. He completed a six-week course of ertapenem with subsequent resolution of the tricuspid valve vegetation on follow-up imaging. After infection clearance, a transvenous dual-chamber pacemaker was successfully implanted. CONCLUSIONS: This case highlights an uncommon presentation of ESBL-producing E. coli TVIE complicated by advanced AV block. It underscores the importance of early transesophageal imaging in suspected right-sided endocarditis, awareness of conduction disturbances as a marker of disease severity, and the role of epicardial pacing as a safe bridging strategy when permanent transvenous systems are contraindicated during active infection.