Direct identification of bacteria in positive blood cultures: comparison of two rapid methods, FilmArray and mass spectrometry

Abstract

We evaluated the accuracy and performance of the FilmArray Direct from Positive Blood Culture system (BCID) (BioFire Diagnostics, Salt Lake City, UT, USA) and the VITEK Mass Spectrometry System (Vitek MS; bioMerieux, Durham, NC, USA) to identify bacterial isolates from 161 positive blood culture bottles. The BCID uses multiplex PCR to identify 90–95% of common isolates to the genus or species/complex level as well as mecA, Van A/B, and blaKPC genes in approximately 1 hour. Of 151 monomicrobic isolates, the FilmArray correctly identified 48/49 (98%) to the genus and 84/84 (100%) to the species/complex level, while 18/151 (12%) gave no identification, as expected from the database. Mass spectrometry correctly identified 142/151 (94%) monomicrobic cultures to the genus level, 137/151 (91%) to the species level, with only 8/151(5%) giving no identification. Although mass spectrometry has a much larger database, the filtration system was cumbersome in contrast to the 3–5 minutes hands-on-time for the BCID.