Streptococcus bovis bacteraemia: an evaluation of the long-term effect on cardiac outcomes

Abstract

Streptococcus bovis can lead to bacteraemia, septicaemia, and ultimately endocarditis. The objective of this study was to evaluate the long-term implications of S. bovis endocarditis on cardiac morbidity and mortality. A retrospective cohort study was performed between January 2000 and March 2009 to assess all patients diagnosed with S. bovis bacteraemia from the Belfast Health and Social Care Trust. The primary end-point for cardiac investigations was the presence of endocarditis. Secondary end-points included referral for cardiac surgery and overall mortality. Sixty-one positive S. bovis blood cultures from 43 patients were included. Following echocardiography, seven patients were diagnosed with infective endocarditis (16.3% of total patients); four patients (9.3%) had native valve involvement while three (7.0%) had prosthetic valve infection. Five of these seven patients had more than one positive S. bovis culture (71.4%). Three had significant valve dysfunction that warranted surgical repair/replacement, one of whom was unfit for surgery. There was a 100% recurrence rate amongst the valve replacement patients (n=2) and six patients with endocarditis had colorectal pathology. Patients with endocarditis had similar long-term survival as those with non-endocarditic bacteraemia (57.1% alive vs. 50% of non-endocarditis patients, p=0.73). Streptococcus bovis endocarditis patients tended to have pre-existing valvular heart disease and those with prosthetic heart valves had higher surgical intervention and relapse rates. These patients experienced a higher rate of co-existing colorectal pathology but currently have reasonable long-term outcomes. This may suggest that they represent a patient population that merits consideration for an early surgical strategy to maximise long-term results, however, further evaluation is warranted.