Paravalvular leak of a mechanical mitral valve prosthesis associated with Burkholderia cepacia subacute endocarditis: a rare case successfully treated by multidisciplinary approach

Prosthetic valve endocarditis (PVE) represents an uncommon and very serious complication after heart valve surgery. Prosthetic valve endocarditis occurs in 1% to 6% of patients with valve prostheses and affects both mechanical and biological valves [1]. Up to 34% of all cases of infective endocarditis involve prosthetic heart valves. Prosthetic valve endocarditis represents a nosographic entity independent from native valve endocarditis (NVE) because of its specific clinical features, epidemiology, and microbiological findings; its management is complex and requires a multidisciplinary approach [2]. Anatomical signs of infective endocarditis in the mitral position include valve dysfunction, paravalvular leaks, and annular abscesses. In particular, the incidence of paravalvular leaks (PVL) is estimated at 2–17%: they can be asymptomatic conditions that do not always require treatment or can cause hemolysis and heart failure [2]. Burkholderia cepacia is a Gram-negative bacillus that represents an important nosocomial pathogen, especially in patients affected by cystic fibrosis and chronic granulomatous diseases [3]. It is rarely responsible for endocarditis in community settings, but sporadic cases have been described among intravenous heroin users and patients with prosthetic valves. According to the clinical data, most patients are treated by administration of trimethoprim-sulfamethoxazole even if the microorganism is actually characterized by multidrug resistance [4]. We present the case of a female patient who was submitted to redo cardiac surgery due to echocardiographic evidence of a paravalvular prosthetic mitral valve leak causing severe regurgitation; intraoperative evaluation revealed anatomical signs of previously undetected endocarditis, while cultures from the prosthetic valve indicated the presence of a very rare microorganism: Burkholderia cepacia. A 75-year-old woman with history of previous mitral valve replacement with a mechanical prosthesis (St. Jude 31-mm valve in 2001) was admitted to our department with the diagnosis of prosthesis dysfunction due to a paravalvular leak and critical stenosis of the left anterior descending coronary artery. The patient was in atrial fibrillation; her medical history featured a previous stroke (2 years before). In May 2016, the patient presented with fever and dyspnea and was admitted to the Internal Medicine Ward of one of our referral hospitals with the diagnosis of bronchopneumonia. After a thoracic computed tomography (CT) scan, an empiric antibiotic therapy with ceftriaxone and clarithromycin was administered. Due to a new onset of systolic murmur, the patient underwent transthoracic and transesophageal echocardiography (TTE and TEE), which demonstrated mitral valve prosthesis dysfunc-