Bacterial rapid identification with matrix assisted laser desorption/ionization time-of-flight mass spectrometry: development of an 'in-house method' and comparison with Bruker Sepsityper(®) kit.

OBJECTIVE: The objective of this study was to compare an in-house matrix-assisted laser desorption ionization with time of flight (MALDI-TOF) method and a commercial MALDI-TOF kit (Sepsityper(®) kit) for direct bacterial identification in positive blood cultures. We also evaluated the time saved and the cost associated with the rapid identification techniques. METHODS: We used the BACTEC(®) automated system for detecting positive blood cultures. Direct identification using Sepsityper kit and the in-house method were compared with conventional identification by MALDI-TOF using pure bacterial culture on the solid phase. We also evaluated different cut-off scores for rapid bacterial identification. RESULTS: In total, 127 positive blood vials were selected. The rate of rapid identification with the MALDI Sepsityper kit was 25.2% with the standard cut-off and 33.9% with the enlarged cut-off, while the results for the in-house method were 44.1 and 61.4%, respectively. Error rates with the enlarged cut-off were 6.98 (n = 3) and 2.56% (n = 2) for Sepsityper and the in-house method, respectively. Identification rates were higher for gram-negative bacteria. DISCUSSION: Direct bacterial identification succeeded in supplying rapid identification of the causative organism in cases of sepsis. The time taken to obtain a result was nearly 24  hours shorter for the direct bacterial identification methods than for conventional MALDI-TOF on solid phase culture. Compared with the Sepsityper kit, the in-house method offered better results and fewer errors, was more cost-effective and easier to use.

[Serum protein electrophoresis: comparison of capillary zone electrophoresis Capillarys (Sebia) and agarose gel electrophoresis Hydrasys (Sebia)]. / Electrophorèse des protéines sériques: comparaison de la technique en capillaire de zone Capillarys (Sebia) et de l'électrophorèse en gel d'agarose Hydrasys (Sebia).

Since several years, serum proteins electrophoresis became a routine analysis, mainly performed by agarose gel electrophoresis, frequently semi-automated. We compared the new fully automated capillary electrophoresis system from Sebia, Capillarys, with our reference method, agarose gel electrophoresis Hydrasys (Sebia). This study focused on the evaluation of both the analytical performances and some practical aspects such as ease of use, rapidity, costs. It appears clearly from that study that both methods give similar results for the detection of monoclonal proteins. We notice that the capillary electrophoresis (Capillarys) displays higher sensitivity (97.2%) than the agarose gel electrophoresis Hydrasys (93.5%), however with a lower specificity (93.7 versus 98.9%). On the other hand, the Capillarys method displays obvious practical advantages such as full automation, ease of use and rapidity.