Clinical impact of a multiplex real-time PCR assay (SeptiFast^®) for the rapid detection of pathogens in patients with end-stage heart failure bridged to heart transplantation with ventricular assist devices

Introduction

Implantable ventricular assist devices (VADs) are widely used in patients with end-stage heart failure as a bridge to heart transplantation (HTx) or as destination therapy (DT); however, their use is associated with increased postoperative infection-related morbidity and mortality. Rapid identification of responsible organisms is imperative for the initiation of appropriate treatment and for lowering mortality due to sepsis. Direct detection of pathogens in blood samples by nucleic acid amplification is a sensitive and fast alternative to blood cultures. The multiplex real-time PCR system SeptiFast^® (Roche Diagnostics) allows for rapid detection and identification of the 25 most common pathogens (Gram-positive and Gram-negative bacteria and fungi) in blood, in less than 6 hours. The aim of this study was to evaluate the usefulness of SeptiFast^® in patients with implanted VADs.

Methods

The study included 103 blood samples from 38 VAD patients analyzed over a period of 24 months (January 2008 to December 2009), using SeptiFast^® in parallel with blood cultures. Blood samples were obtained only from patients suspected of harboring an infection, and in case of positive results follow-up samples were obtained on a weekly basis. PCR was performed according to manufacturers' description (SeptiFast^®) using MagnaLyser for extraction of DNA from 1.5 ml peripheral blood and LightCycler 2.0 (Roche Diagnostics) for amplification and detection.

Results

SeptiFast^® and blood cultures yielded concurrent negative results in 76% of the samples and positive results in 7.3% of them. There was a 75% concordance in species identification. Diverging results were obtained in 10.3% of the samples where SeptiFast^® only was positive and in 6.4% of the samples where blood cultures only were positive. In cases with concurrent positivity, acceptance of the SeptiFast^® results could have led to an earlier targeted treatment.

Conclusions

The PCR-based SeptiFast^® test in combination with traditional microbiological methods may facilitate fast and specific antibiotic treatment and may contribute to reduction of sepsis progressing infections in VAD patients.