A retrospective evaluation of a multiplex polymerase chain reaction test directly applied to blood for the management of sepsis in the critically ill.

Background: Blood culture (BC) is the established gold standard for microbiological diagnosis of bloodstream infection (BSI); however, its sensitivity is poor. Objectives: The primary objective was to determine the sensitivity and specificity of the Magicplex Sepsis Real-time Test, a multiplex polymerase chain reaction test (mPCR), and BC to detect BSIs. Secondary outcomes included determining the prevalence of BSIs. Methods: A retrospective review of a technical evaluation of the mPCR. Patients requiring BC had a blood sample collected for mPCR. Results: The respective sensitivity and specificity of mPCR for the detection of BSI were 50% (n=7/14) and 58% (n=18/31), while the sensitivity and specificity using BC were 36% (n=5/14) and 68% (n=21/31), respectively. The addition of mPCR to BC increased BSI detection during sepsis from 36% to 64%. Conclusion: The use of mPCR directly applied to blood may increase the detection of micro-organisms associated with BSIs in critically ill patients requiring BC investigation. Contributions of the study: Our data add to a growing body of evidence indicating that mPCR applied directly to blood prior to incubation increases the detection of pathogenic bacteria among hospitalised patients for whom blood cultures are performed for suspected infection. Our study was performed in a low-to-middle income country with a higher sepsis prevalence, a greater burden of multidrug-resistant organisms and clinically defined sepsis. This strengthens the robustness and generalisability of this body of evidence.