Short Communication: Evaluation of MALDI-TOF and Sequencing Technique as Typing Tools for Enterobacteriaceae Bacteria from Raw Milk of Dairy Cows with Subclinical Mastitis

Subclinical mastitis is an udder infection and inflammation in dairy animals that causes no visible changes in the milk or udder, making it hard to detect. Animal welfare and health are negatively impacted by dairy cow mastitis, which also severely impairs the dairy industry’s financial standing. This study was carried out in the three local Municipalities of Free State Province, South Africa, sought to determine bacterial contamination of raw milk of cows infected with subclinical mastitis using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and 16S rRNA Sanger sequencing. From subclinical mastitic samples, our MALDI-TOF results revealed coliform bacteria such as Pseudomonas oryzihabitans with 25/71 (32.21%) as a dominant species, followed by Pseudomonas aeruginosa, Escherichia coli, Pantoea agglomerans and Enterobacter kobei at 9/71 (12.67%), 8/71 (11.27%), 6/71 (8.45%) and 6/71 (8.45%), respectively. Finally, Enterococcus faecalis, Enterococcus faecium, Micrococcus luteus, Routella ornithinolytica were detected at 3/71 (4.22%) each and 1 sample with mixed species of Routella platicola 1/71 (1.40%) and Routella ornithinolytica at 1/71 (1.40%). The most frequent microbes causing dairy cow mastitis can be identified using MALDI-TOF MS, a technique that is strong, quick, and accurate. With the inclusion of new species, the database can be enhanced and expanded over time.