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Evaluation of molecular detection of bloodstream pathogens in 144 patients arriving in the emergency room with clinical signs of sepsis

Abstract number: P1806

Avolio M., Diamante P., Zamparo S., Modolo M.L., Grosso S., Zigante P., Tosoni N., De Rosa R., Stano P., Camporese A.

Objectives: In this study we wished to compare traditional Blood Culture (BC) with multiplex Real-time PCR, LightCycler SeptiFast Test M Grade (Roche Molecular System), in 144 patients with suspected bloodstream infections arriving at emergency room (ER) in order to know the agreement degree about those two methods applied in this category of patients.

Methods: 144 adult patients admitted to ER of our hospital with at least two criteria of the systemic inflammatory response syndrome were included in the study. During a febrile episode a single venipuncture was used to draw samples for 2 x 3 bottles of Bact/Alert (bioMérieux, Marcy l'Etoile, France). Immediately after the blood was drawn for the BC (8–10 mL/bottle), a 1.5 mL of whole blood was collected in sterile EDTA-KE tubes (Sarstedt, Nümbrecht, Germany) for the molecular method.

Results: SeptiFast results were compared with the results obtained with all culture bottles taken on different time points during a 24-h period and arrived simultaneously in our laboratory, showing a sensitivity of 92.5%, a specificity of 91% with a PPV and NPV of 78.7% and 97.1% rescpectively (values obtained by excluding CoNS and DNA not detectable by SeptiFast).

A median of 36 hours was necessary to obtain Gram staining and at least 72 hours, calculated from the arrival of the sample to the laboratory, for final bacterial species identification of pathogens using blood culture and biochemical identification. A median time of 15 hours (range 6–30 hours) was sufficient to obtain a molecular analytical result.

Conclusion: Several studies have underlined the limitations of both molecular and BC methods in diagnosis of BSI (Westh et al. Clin Microbiol Infect 15(6), 2009; Bouza et al. Clin Infect Dis 39, 2004). Our study confirms that SeptiFast is limited by its test menu, the specificity of its primers and probes, and the genetic variability of the target site, but on the other hand, an inadequate sample volume, antimicrobial therapy before drawn or the number of repeated blood draws affected the sensitivity of BC. On the basis of our results, either in terms of concordance of results, either in terms of TAT, despite its limitations, SeptiFast could be useful as an adjunct to traditional culture methods to facilitate detection of BSI (Andrade et al. Shock 30(1), 2008), especially in cases where BC is negative, but BSI is strongly suggested. For these clinical conditions we wish to further investigate the use of SeptiFast.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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