Evaluation of MALDI-TOF for identification of Vibrio cholerae and Vibrio parahaemolyticus from growth on agar media.

Two methods were compared for their ability to accurately identify Vibrio species of interest: whole genome sequencing as the reference method and MALDI-TOF MS (matrix-assisted laser desorption/ionization-time of flight mass spectrometry) proteome fingerprinting. The accuracy of mass spectrometry-based identification method was evaluated for its ability to accurately identify isolates of Vibrio cholerae and Vibrio parahaemolyticus. Identification result of each isolate obtained by mass spectrometry was compared to identification by whole genome sequencing (WGS). The MALDI-TOF MS system had excellent performance for identification of V. cholerae and V. parahaemolyticus isolates grown on a non-selective solid agar media. Unlike the biochemical characterization performed by API20E. In this study, 161 isolates (V. cholerae, n = 33; V. parahaemolyticus, n = 102; V. spp., n = 23; other enteropathogens, Salmonella and E. coli, n = 3) were used to assess accuracy. The MALDI-TOF MS system was able to accurately identify 100% (33/33) of the V. cholerae isolates and 99.9% (101/102) of V. parahaemolyticus isolates, with 100% for both sensitivity and specificity for V. cholerae and 99% sensitivity and 98% specificity for V. parahaemolyticus. Thus, mass spectrometry for bacterial identification is comparable to the WGS. Furthermore, in comparison to a biochemical characterization, the use of MALDI-TOF MS system shortens the analysis time from over 72 h to less than 24 h. KEY POINTS: • V. cholerae and V. parahaemolyticus were successfully ID-ed by MALDI-TOF • MALDI-TOF sensitivity and specificity parallels the WGS method of identification • MALDI-TOF is several days faster than the battery of culture-dependent methods.