Rapid diagnosis of the causative organism of invasive infections is critical to the improved care of patients. A new platform, FilmArray (BioFire Diagnostics, LLC, Salt Lake City, UT) allows for rapid PCR to be performed in less than two hours on positive blood cultures
The aim was to perform a retrospective diagnostic accuracy study in a paediatric tertiary referral hospital comparing results from culture, our gold standard, against those obtained when the samples were tested directly using the FilmArray Blood Culture Identification (BCID) Panel (BioFire Diagnostics, LLC, Salt Lake City, UT).
Samples from sterile site infections were tested using traditional culture based methods as well as PCR testing, and these results were then compared to testing which was done directly on the FilmArray BC-ID panel.
Ninety-four samples were tested in total and concordant results were observed in 71 samples (76%). Correlation between detection of pathogens such as Staphylococcus aureus and Streptococcus pyogenes by PCR and culture result was high (94% and 88% respectively). Discordant results could be explained by the cultured organism not having a target on the panel (n=8) or PCR detection of potentially non-viable bacteria in the sample (n=8); the remaining samples (n=9) were negative by PCR despite culturing an organism with a target present on the panel for that organism. We have demonstrated an overall correlation of 76% and that in some instances the PCR detected non-viable yet clinically significant bacteria.
Use of the FilmArray BCID panel directly for samples from sterile sites should be considered when there is a high index of suspicion of a single-organism infection at that site prior to sampling.