Helsinki, Finland, Dec 10, 2009 - Identification of sepsis-causing bacteria using a new microarray platform is highly accurate and delivers results an average of 18 hours faster than the conventional culture-based system. These conclusions are published in the high-graded medical journal, The Lancet, first online (www.thelancet.com) and in the upcoming edition, written by Dr Vanya Gant* and Dr Päivi Tissari**and colleagues.
Rapid identification of bacteria commonly causing sepsis could allow species-specific therapy to be started early, leading to improved clinical outcomes. The current gold standard for detection of bacteria from septic patients is blood culture, typically taking 1–3 days to become positive. A further 1–2 days are needed for bacterial identification and antibiotic sensitivity testing. New rapid and accurate diagnostic tests are needed to cut this additional time period shorter.
Novel DNA-based microarray platforms now allow rapid identification of several microbial pathogens simultaneously. Mobidiag’s Prove-it Sepsis assay identifies 64 bacterial species thus covering most cases of sepsis. The assay works through amplification and detection of three bacterial genes. In the study, the sensitivity, specificity, and time to identification of this molecular platform were compared with the conventional culture-based method.
During the study, 2107 positive blood-cultures in 3318 blood samples from patients with clinically suspected sepsis were analyzed side by side with the conventional culture method and the Prove-it Sepsis assay in two laboratories (UK and Finland). The results show that 1807 of 2107 (86 %) positive blood-culture samples included a pathogen covered by the assay. The clinical sensitivity was 95 % and specificity 99 %, and 100 % for both measures for meticillin-resistant Staphylococcus aureus bacteraemia. The assay was a mean 18 h faster than the conventional method, which in practice means additional 1–2 working days.
The authors say that the Prove-it sepsis assay yielded a high sensitivity and specificity, and identified bacterial species about 18 h before conventional culture methods did, providing practical and realistic delivery of same-day bacterial identification. Clinical sensitivity and specificity of the assay were 100% for MRSA bacteraemia. Mobidiag’s R&D director Minna Mäki lauds their research partners for great co-operation and is very enthusiastic about continuing the study with these experts. The next study will be designed to investigate the effects of the test results on the health-care costs. Although the assay brings additional costs in making the diagnosis, the early identification of pathogens enables effective targeted antimicrobial treatment, might save expensive hospital days and improve the patient outcome.
In an accompanying comment*** the work by Gant and co-workers is considered a major advance in sepsis diagnostics although further study is needed before widespread application. By combining elements of molecular biology and standard culture-based methods, the Prove-it Sepsis brings together the best of both worlds. “Publishing this high-grade scientific study in The Lancet, the most respected journal in the field of medicine, is a great acknowledgment of our test quality and will definitely set the scene for the international break-through in sepsis diagnostics”, says Jaakko Pellosniemi, the CEO of Mobidiag.
*University College London Hospitals NHS Foundation Trust, University College London Windeyer Institute, Lontoo, Iso-Britannia.**Helsingin ja Uudenmaan Sairaanhoitopiiri, HUSLAB, Helsinki.***Dr Shin Lin, Stanford University School of Medicine, Stanford, CA, USA ja Dr Samuel Yang, Department of Emergency Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA.
More information: Jaakko Pellosniemi, Mobidiag, tel. 358 40 501 1004, info@mobidiag.com