MALDI-TOF: A Rapid Identification of Dairy Pathogens

Abstract The proposed research study is a field validation study to benchmark against proven methods, a new methodology for the detection of microorganisms (Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry or MALDI-ToF) isolated from dairy farm and critical for safety and quality. The MALDI-TOF is a relatively new molecular technique extremely advantageous in terms of cost effectiveness, sample preparation easiness, turn-around time and result analysis accessibility. Although already successfully deployed in clinical diagnostic, it has not been evaluated for agricultural applications yet. In the dairy industry, Mastitis causes the most financial loss and a rapid diagnostic method as MALDI-TOF, will assist in the control and prevention program of mastitis, in addition to the sanitation and safety level of the dairy farms and processing facility. In the present study, we prospectively compared MALDI-TOF MS to the conventional 16S rRNA sequencing method for the identification of environmental mastitis isolates (481) and thermoduric isolates of pasteurized milk (248). Among the 481 environmental isolates, 454 (94.4%) were putatively identified to the genus level by MALDI-TOF MS and 426 (88.6%) were identified to the species level, but no reliable identification was obtained for 17 (3.5%), and 27 (5.6%) discordant results were identified. Future studies can help to overcome the limitation of MALDI database and additional sample preparation steps might help to reduce the number of discordance in identification. In conclusion, our results show that MALDI-TOF MS is a fast and reliable technique which has the potential to replace conventional identification methods for most dairy pathogens, routinely isolated from the milk and dairy products. Thus it’s adoption will strengthen the capacity, quality, and possibly the scope of diagnostic services to support the dairy industry