Multicenter evaluation of the Sepsityper™ extraction kit and MALDI‐TOF MS for direct identification of positive blood culture isolates using the BD BACTEC™ FX and VersaTREK® diagnostic blood culture systems

• Published in: Journal of applied microbiology 2014-04, Vol.116 (4), p.934-941
• Main Authors: Schieffer, K.M, Tan, K.E, Stamper, P.D, Somogyi, A, Andrea, S.B, Wakefield, T, Romagnoli, M, Chapin, K.C, Wolk, D.M, Carroll, K.C
• Format: Article
• Language: English
• Subjects: bacteraemia; Bacteremia - diagnosis; Bacteria - isolation & purification; Bacterial Proteins - analysis; Bacterial Proteins - isolation & purification; Bacteriological Techniques - methods; Biological and medical sciences; Biotechnology; Blood; blood cultures; blood volume; Fundamental and applied biological sciences. Psychology; Humans; MALDI‐TOF MS; matrix-assisted laser desorption-ionization mass spectrometry; Microbiology; pellets; proteins; sepsis; Sepsityper; shipping; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; technology; temperature
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/jam.12434

AIMS: (i) Evaluation of delayed time to blood culture extraction by the Sepsityper kit and impact of shipping pellets off‐site for MALDI‐TOF MS analysis. (ii) Comparison of Sepsityper and laboratory‐developed extraction methods from a literature review. METHODS AND RESULTS: Using two blood culture systems (BD BACTEC and VersaTREK), we extracted 411 positive blood cultures using the Sepsityper kit to mimic a potential protocol for institutions without a MALDI‐TOF MS. Extracted pellets were shipped and analysed on the Bruker UltraflexIII. Successful extraction of 358 (87·1%) samples was determined by the presence of detectable proteins. MALDI‐TOF MS correctly identified 332 (80·8%) samples. CONCLUSIONS: Delayed time to extraction did not affect Sepsityper extraction or MALDI‐TOF MS accuracy. The extracted pellets remain stable and provide accurate results by MALDI‐TOF MS when shipped at room temperature to off‐site reference laboratories. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to show that institutions without a MALDI‐TOF MS can take advantage of this innovative technology by shipping a volume of blood to an off‐site laboratory for extraction and MALDI‐TOF MS analysis. We also performed a literature review to compare various extraction methods.