Clinical and morphological characteristics in Streptococcus bovis endocarditis: a comparison with other causative microorganisms in 177 cases

Abstract

Aim: To compare the clinical and morphological characteristics of patients with Streptococcus bovis endocarditis with those of patients with endocarditis caused by other microorganisms.

Methods: 177 consecutive patients (Streptococcus bovis, 22; other streptococci, 94; staphylococci, 44; other, 17) with definite infective endocarditis according to the Duke criteria were included. All patients underwent transthoracic and transoesophageal echocardiography. In 88 patients, findings from surgery/necropsy were obtained.

Results: S bovis endocarditis was associated with older patients, with a higher mortality (p = 0.04), and with a higher rate of cardiac surgery (p < 0.001) than other microorganisms, although embolic events were observed less often (p = 0.02). Pathological gastrointestinal lesions were detected in 45% of the patients. Multiple valves were affected in 68% of the patients with S bovis endocarditis and in 20% of those with other organisms (p < 0.001). Moderate or severe regurgitation occurred more often in S bovis endocarditis than with other microorganisms (p = 0.05). When surgery or necropsy was performed, infectious myocardial infiltration of the left ventricle was confirmed histopathologically in 36% of the patients with S bovis endocarditis and in 10% of those with other organisms (p = 0.002).

Conclusions: S bovis endocarditis is a severe illness because of the more common involvement of multiple valves, and of the frequent occurrence of haemodynamically relevant valvar regurgitation and infectious myocardial infiltration.

Figure 1

Cumulative survival rates in 177 patients with infective endocarditis between 1983 and 1996. (Numbers below graph are patients at risk 6, 12, 24, 48, and 96 months after hospital discharge.) *p < 0.05.

Figure 2

Frequency of multiple valve endocarditis in 177 patients. n, number of affected valves/patient.