Rapid serodiagnosis of Gram-positive bacterial endocarditis

Objectives: To characterize a serological test for diagnosing endocarditis caused by Gram-positive cocci. Methods: We have developed an indirect enzyme-linked immunosorbent assay (E LISA) for the serological detection of Gram-positive infections. The test m easures serum Ige directed towards lipid S, a recently identified exocellul ar glycolipid antigen which is related to lipoteichoic acid. We have previo usly shown the test to be of value in serodiagnosis of central venous cathe ter-associated sepsis and infection of orthopaedic prostheses caused by coa gulase-negative staphylococci, We now describe the application of this test in endocarditis. Results: Serum IgG levels to lipid S were significantly elevated in 34 pati ents with Gram-positive bacterial endocarditis confirmed as 'definite' by t he Duke criteria as compared to 50 control patients. The test had a sensiti vity of 88% and a specificity of 88%. Conclusions: The assay is independent of culture results or endocardial ima ging, making it complementary to currently used investigations. It may ther efore be possible to refine the current Duke criteria for diagnosing endoca rditis. We describe an algorithm which incorporates lipid S serology into a positive diagnostic strategy, (C) 2001 The British Infection Society.