Päivi Tissari MD a, Prof Alimuddin Zumla FRCP b, Eveliina Tarkka MSc a, Sointu Mero MSc a, Laura Savolainen MSc a, Martti Vaara MD a, Anne Aittakorpi BEng c, Sanna Laakso c, Merja Lindfors BLS c, Heli Piiparinen PhD c, Minna Mäki PhD c, Caroline Carder FIBMS b, Jim Huggett PhD b, Dr Vanya Gant FRCP b. The Lancet, Early Online Publication, 10 December 2009doi:10.1016/S0140-6736(09)61569-5
The Prove-it Sepsis assay used in the study. Read more at its website here.
Background: New DNA-based microarray platforms enable rapid detection and species identification of many pathogens, including bacteria. We assessed the sensitivity, specificity, and turnaround time of a new molecular sepsis assay.

Methods
2107 positive blood-culture samples of 3318 blood samples from patients with clinically suspected sepsis were investigated for bacterial species by both conventional culture and Prove-it sepsis assay (Mobidiag, Helsinki, Finland) in two centres (UK and Finland). The assay is a novel PCR and microarray method that is based on amplification and detection of gyrB, parE, and mecA genes of 50 bacterial species. Operators of the test assay were not aware of culture results. We calculated sensitivity, specificity, and turnaround time according to Clinical and Laboratory Standards Institute recommendations.
Findings
1807 of 2107 (86%) positive blood-culture samples included a pathogen covered by the assay. The assay had a clinical sensitivity of 94·7% (95% CI 93·6—95·7) and a specificity of 98·8% (98·1—99·2), and 100% for both measures for meticillin-resistant Staphylococcus aureus bacteraemia. The assay was a mean 18 h faster than was the conventional culture-based method, which takes an additional 1—2 working days. 34 of 3284 (1·0%) samples were excluded because of technical and operator errors.
Interpretation
Definitive identification of bacterial species with this microarray platform was highly sensitive, specific, and faster than was the gold-standard culture-based method. This assay could enable fast and earlier evidence-based management for clinical sepsis.
Funding
None.

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