Performance Assessment of the VITEK MS to Confirm Characteristic Colonies after Screening for Cronobacter spp. Detection with ESIA One Day

Introduction: VITEK^® MS is an automated microbial identification system that uses MALDI-TOF (Matrix Assisted Laser Desorption Ionization Time-of-Flight) technology. In few minutes, this mass spectrometry technology can provide clear confirmation of characteristic colonies after a first screening for Cronobacter spp detection with ESIA One Day.

Purpose: An independent study was conducted at Adria to validate VITEK MS as a confirmation method according to the NF Validation technical rules and approval process.

Methods: One hundred and fifty two Cronobacter spp strains and 100 gram negative non-target strains, mainly from the Enterobacteriaceae family, were tested. The Cronobacter spp. strains were enriched according to the ESIA One Day protocol. The non-target strains were cultured in a non-selective broth, i.e., BHI. All the strains were streaked on ESIA selective agar, as well as non-selective TSA plates. Isolated colonies were tested for confirmation with the VITEK MS.

Results: One hundred Cronobacter strains were correctly confirmed as Cronobacter spp., “no result” outputs were obtained with the VITEK MS for 4 of the target strains. None of the non-target strains were confirmed as Cronobacter spp., 63 of them were not able to recover on ESIA. 

Significance: Due to its robust database, VITEK MS is an accurate and rapid technology to confirm ESIA One Day positive presumptive results.