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Is multiplex PCR (SeptiFast) useful for diagnosis of infectious endocarditis?

Abstract number: P1832

Conen A., Schaub N., Achermann Y., Battegay M., Frei R., Trampuz A.

Objectives: Blood cultures (BC) represent the main diagnostic tool in patients with suspected infectious endocarditis (IE). However, BC can be false-negative when difficult-to-culture microorganisms are involved or patients have received previous antibiotic treatment. The multiplex real-time PCR SeptiFast (Roche Diagnostics) is a culture-independent method that detects microbial DNA of 25 bacterial and fungal pathogens within 6 h. We assessed the diagnostic value of SeptiFast in comparison with BC in patients with IE.

Methods: We prospectively included adult patients with suspected native or prosthetic valve IE, defined as at least 2 SIRS criteria plus 1 major Duke criterion (i.e. bacteraemia with a typical microorganism or evidence of endocardial involvement by echocardiography), presenting in the emergency room. Blood was simultaneously drawn for BC (BacT/ALERT FA/FN, bioMérieux) and for SeptiFast (1.5 ml EDTA-blood). If the heart valve was removed, culture, histology and broad-range PCR were performed. Patients were retrospectively classified according to Duke criteria by 2 independent investigators, blinded to the SeptiFast results, into confirmed or rejected IE.

Results: In this ongoing study (07–12/2008), 23 patients were included, of whom IE was confirmed in 9 (39%) and rejected in 14 (61%). Among 9 patients with confirmed IE (median age 50 y, range 34–80 y, 44% males), BC grew the pathogen in 6 (67%) including Staphylococcus aureus (n = 3), Streptococcus mitis (n = 2) and S. gallolyticus (n = 1); SeptiFast detected pathogens in 8 of 9 IE-patients (89%), among whom 6 matched BC, 1 patient was positive in SeptiFast only (Escherichia coli) and 1 in broad-range PCR of the valve (S. agalactiae). In 1 patient with negative BC and negative SeptiFast, Haemophilus sp. was detected by broad-range PCR of the valve. 2 of 3 patients with negative BC received antibiotics before blood collection, among whom both were positive by SeptiFast. IE involved 4 native, 3 prosthetic (all aortic) and 1 native + prosthetic valve; in 1 patient the valve was not involved, but 3 minor Duke criteria were fulfilled.

Conclusions: BC detected 6 of 9 (67%) organisms causing IE, whereas SeptiFast 8 of 9 (89%). SeptiFast detected all 8 organisms for which specific primers are included in the test kit and deserves further investigation in the diagnosis of intravascular infections. A modified primer set may further improve detection of organisms causing IE, including culture-negative IE.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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