Clinical prediction scores and the utility of time to blood culture positivity in stratifying the risk of infective endocarditis in Staphylococcus aureus bacteraemia

Abstract

Background Infective endocarditis (IE) complicates up to a quarter of Staphylococcus aureus bacteraemia (SAB) cases. Risk scores predict IE complicating SAB but have undergone limited external validation, especially in community-acquired infections and those who use IV drugs. Addition of the time to positive culture (TTP) may provide incremental risk prognostication. Objectives To externally validate risk scores for predicting IE in SAB and assess the incremental value of TTP. Methods The modified Duke score was calculated for adults hospitalized with SAB at a major tertiary institution. All patients underwent echocardiography. Sensitivity and specificity of the risk scores for predicting IE were calculated, and the incremental value of TTP was assessed. Results One hundred and six cases were analysed and 18 (17%) met definite IE criteria. The optimal TTP to predict IE was 11.5 h (sensitivity 88.9%; specificity 71.6%). The sensitivity of VIRSTA and PREDICT (Predicting risk of endocarditis using a clinical tool) were similar (94.4% for both) and higher than POSITIVE (Prediction Of Staphylococcus aureus Infective endocarditis Time to positivity, IV drug use, Vascular phenomena, pre-Existing heart condition; 77.8%). The receiver-operator characteristic AUCs were VIRSTA 0.83, PREDICT 0.75, POSITIVE 0.89 and TTP 0.85. Adding TTP to VIRSTA (i.e. VIRSTA+) resulted in the highest AUC (0.90), sensitivity (100%) and negative predictive value (100%), albeit with a low specificity (33%). Conclusions The VIRSTA and POSITIVE scores were the strongest predictors for IE complicating SAB. The addition of TTP to VIRSTA (VIRSTA+) significantly improved discriminatory value and may be safely used to rationalize echocardiography strategies.

Update on Staphylococcus aureus bacteraemia

“…SAB is complex and there are many important aspects that we were not able to explore further at this time including a study with eosinophilia with daptomycin [40], use of oral stepdown therapy with clindamycin [41], improvement of diagnosis using fluorodeoxyglucose positron emission tomography/ computed tomography (FDG-PET/CT) [42,43], source control such as with removal of cardiac implantable electronic devices associated with decreased mortality [44], the importance of serial negative blood cultures [45 & ], and the significance of Staphylococcus aureus bacteriuria in patients with SAB [46 & ]. In addition, optimized use of clinical scoring systems to stratify patients for therapy or best utilize echocardiography resources is a major area of investigation that could merit its own review [47][48][49][50][51][52][53][54].…”