Diagnosis of blood culture-negative endocarditis and clinical comparison between blood culture-negative and blood culture-positive cases
To analyze the clinical characteristics of blood culture-negative endocarditis (BCNE) and how it compares to those of blood culture-positive endocarditis (BCPE) cases and show how molecular tools helped establish the etiology in BCNE.
Adult patients with definite infective endocarditis (IE) and having valve surgery were included. Valves were studied by polymerase chain reaction (PCR). Statistical analysis compared BCNE and BCPE.
One hundred and thirty-one patients were included; 53 (40 %) had BCNE. The mean age was 45 ± 16 years; 33 (62 %) were male. BCNE was community-acquired in 41 (79 %). Most patients were referred from other hospitals (38, 73 %). Presentation was subacute in 34 (65 %), with fever in 47/53 (90 %) and a new regurgitant murmur in 34/42 (81 %). Native valves were affected in 74 %, mostly left-sided. All echocardiograms showed major criteria for IE. Antibiotics were used prior to BC collection in 31/42 (74 %). Definite histological diagnosis was established for 35/50 (70 %) valves. PCR showed oralis group streptococci in 21 (54 %), S. aureus in 3 (7.7 %), gallolyticus group streptococci in 2 (5.1 %), Coxiella burnetii in 1 (2.5 %) and Rhizobium sp. in 1 (2.5 %). In-hospital mortality was 9/53 (17 %). Fever (p = 0.06, OR 4.7, CI 0.91–24.38) and embolic complications (p = 0.003, OR 3.3, CI 1.55–6.82) were more frequent in BCPE cases, while new acute regurgitation (p = 0.05, OR 0.3, CI 0.098–0.996) and heart failure (p = 0.02, OR 0.3, CI 0.13–0.79) were less so.
BCNE resulted mostly from prior antibiotics and was associated with severe hemodynamic compromise. Valve histopathology and PCR were useful in confirming the diagnosis and pointing to the etiology of BCNE.
KeywordsInfective endocarditis Negative blood cultures Polymerase chain reaction Valve pathology Diagnostic criteria
We thank all medical and non-medical hospital staff for their care of the patients. We thank Dr. Michael Bruce Macrae, Consultant Microbiologist, London, UK, for language assistance and editing.
Dr. Cristiane Lamas receives a grant from Fundação Nacional de Desenvolvimento do Ensino Superior Particular (FUNADESP) and Dr. Carolina Januário-da-Silva from Fundação de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ), both research supporting agencies in Brazil.
Compliance with ethical standard
Conflict of interest
The authors have no conflict of interest regarding this manuscript.
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