Staphylococcus aureus bacteraemia: evaluation of the role of transoesophageal echocardiography in identifying clinically unsuspected endocarditis

Abstract

Staphylococcus aureus bacteraemia (SAB) is an important cause of community and nosocomial sepsis, with a significant mortality rate. Infective endocarditis (IE) is a serious complication, occurring in up to 25 % of cases. Transoesophageal echocardiography (TOE) significantly improves the sensitivity of diagnosis. We compared the sensitivity and specificity of clinical evaluation alone in diagnosing IE. We evaluated all adult patients with SAB at our centre from 1998 to 2006 in order to determine what proportion of clinically unsuspected cases were diagnosed with IE on TOE. IE was defined according to modified Duke criteria. The median age of the patients was 68 years, 77 % were male and the majority of cases did not have a known pre-existing condition. Twenty-one percent were methicillin-resistant Staphylococcus aureus (MRSA). Intravascular device was the most common cause of bacteraemia. TOE was performed in 144 (100 %) of the cases. IE was suspected clinically in 15 % of cases, and the overall prevalence of possible or definite IE on TOE-inclusive Duke criteria was 29 % (n = 41). Following TOE, 22 (15 %) cases were reclassified as either possible or definite endocarditis. TOE detected a vegetation in 37 (90 %) of the 41 cases of IE. Nineteen (46 %) were not suspected clinically by Duke criteria. Sensitivity improved in the presence of pre-existing valve lesion or community acquisition. The overall in-hospital mortality was 10 %. There is a high incidence of endocarditis in SAB and a large percentage of cases are not evident on clinical grounds. TOE evaluation is indicated for all medically suitable adult patients with SAB in order to improve the detection of endocarditis.

Use of Transthoracic Echocardiography in the Management of Low-Risk Staphylococcus aureus Bacteremia

“…Although 5 high-risk criteria had >97% sensitivity and >99% negative predictive value for IE in nosocomial SAB (14), diagnostic properties were less robust when these criteria were applied to a prospective cohort that also included community-acquired and health careassociated SAB (15). Khatib and Sharma (15) found however, the majority did not receive any form of cardiac imaging (14,15), and other studies with higher rates of echocardiography utilization do not support the use of clinical predictors alone to rule out IE (8,12,19).…”

“…Identification of IE is crucial because patients require a more complex approach to management, which includes prolonged use of intravenous antibiotic therapy (10,11). The majority of patients with IE do not have clinically evident disease at the time of bacteremia, which makes early diagnosis challenging (4, 8,12).…”

Clinical Management ofStaphylococcus aureusBacteremia

“…10 Among 230 Australian patients with SAB, 144 of whom underwent TEE, 46% of IE cases were not suspected on clinical grounds, and 15% of patients without clinical evidence of IE were reclassified by TEE. 14 Most recently, 13 of 98 SAB patients (16%) were found to have IE in a “mandatory TEE” approach. 15 …”

2015 ESC Guidelines for the management of infective endocarditis

“…Zalecenia dotyczące badania echokardiograficznego w diagnostyce i monitorowaniu pacjentów z podejrzeniem IZW podsumowano w tabeli 10 i na rycinie 1. U osób z bakteriemią wywołaną S. aureus wykonanie badania echokardiograficznego uzasadnia duża częstość występowania IZW w tych okolicznościach, zjadliwość drobnoustroju oraz niszczące działanie w przypadku rozwijania się infekcji wewnątrzsercowo [66,67]. U tych pacjentów należy rozważyć wykonanie TTE lub TEE w zależności od indywidualnych czynników ryzyka oraz sposobu powstania bakteriemii S. aureus [66,67].…”