The Mobidiag Prove-it sepsis PCR and microarray platform: a 2centre study designed to validate a system for speciating blood culture bacterial isolates within 3hours
Abstract number: P1835
Tissari P., Mero S., Savolainen L., Tarkka E., Vaara M., Aittakorpi A., Laakso S., Lindfors M., Piiparinen H., Mäki M., Carder C., Huggett J., Gant V.
Objective: Better, more efficient clinical management would flow from quicker identification of organisms in blood culture to taxon and/or species level. The Mobidiag Prove-it Sepsis PCR and microarray platform is designed to speciate the most common blood culture-related organisms within 3 hours of positive blood culture flagging by conventional systems.
Methods: We compared this system's diagnostic performance with conventional identification systems in two major teaching hospitals in Helsinki and London.
Results: 3298 blood cultures were analysed, of which 2087 yielded a pathogen by conventional techniques. Of these, 320 organisms were not covered by appropriate probes, and 135 contained more than one organism. Prove-it Sepsis sensitivity and specificity were 98% and 96%, respectively, for blood cultures containing a single organism within the detection panel. The system provided a result on average 18 hours earlier than conventional systems. Of particular significance was its faultless ability to differentiate MRSA from MSSA and from coagulase negative staphylococci. Investigation of discrepant results revealed 30 cases where the system's sensitivity limits were likely exceeded; other discrepant cases related to human error, likely contamination during the extraction stage, and the system's limitations relating to blood cultures containing more than one organism. Other issues relating to batch reagent variation were also identified and corrected within the trial timeframe. The system proved to be fast, reliable, robust, and rapid, with biochip analysis taking less than 10 seconds per sample.
Conclusions: Both centres identified cases where timely information which only this system could provide would have significantly improved patient management. Examples here include more rational antibiotic choice both through rapid differentiation of MRSA from either S. aureus or coagulase negative staphylococci, and speciation of Gram negative organisms. Once primers and probes for additional targets (specifically Candida spp.) are validated, we aim to perform a cost/benefit trial where decisions made with results provided by this simple, rapid, and robust diagnostic platform will be analysed for their impact on better patient outcome.
|Session name:||19th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Helsinki, Finland, 16 - 19 May 2009|
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