Matrix Assisted Laser Desorption Ionization – Time of Flight Mass Spectrometry Proteomic Based Identification and Characterization of Pathogens Associated with Bovine Mastitis

In the present study bovine milk samples (n = 235) were screened for mastitis with California Mastitis Test (CMT) from Pune and Satara districts of western part of India. It showed prevalence of subclinical mastitis and clinical mastitis to be 60.40% and 2.20% in Pune district whereas, 94.4% and 9.9% in Satara district, respectively. CMT positive samples were inoculated on cultural media and 203 isolates either as single or combined associated with udder infections were generated. All these bacterial isolates were analyzed using MALDI-TOF-MS and the results were compared with classical biochemical methods and PCR assay, specifically for Staphylococcus aureus and E coli. Selective plating and biochemical identification yielded 80 (39.41%) Staphylococcus aureus isolates followed by E. coli 53 (26.11%) while remaining 70 (34.48%) were other minor 32 (15.76%) gram positive and 38 (18.72%) gram negative organisms. Furthermore, S. aureus as well as E. coli organisms were also confirmed by PCR assay by using specific primers targeting FemA gene and 16SrRNA gene, respectively. The results of MALDI-TOF MS technique proved equally (100%) effective in identification of both the species with highest accuracy as compared with bacterial culture and PCR assay, thus demonstrating the receipt of accurate reliability of MALDI-TOF MS in bacterial identification. Additionally, identification of minor mixed bacterial culture illustrated its increased additional utility. In brief, result demonstrated that MALDI-TOF MS can be used in veterinary diagnostic laboratories for identification of different bacterial species involved in mastitis. Hence, efficient animal management strategies for disease and milk quality control in the dairy industry can be implemented.