Performance of MALDI biotyper compared with Vitek™ 2 compact system for fast identification and discrimination of Staphylococcus species isolated from bovine mastitis

This study was designed to evaluate the ability of MALDI Biotyper (MBT) compared with Vitek™ 2 compact system for accurate identification of Staphylococcus aureus (S. aureus) and coagulase-negative staphylococci (CNS) strains and discriminate methicillin-sensitive S. aureus (MSSA) from methicillin-resistant S. aureus (MRSA). Throughout Al-Qassim region, Saudi Arabia, a total of 198 isolates of S. aureus (132 MSSA and 66 MRSA) and 44 CNS were collected from five dairy farms where the prevalence of staphylococcal mastitis was reported. The results produced by Vitek™ 2 compact system demonstrated that 123/132 MSSA isolates (93.18%), 61/66 MRSA (92.42%), and 37/44 CNS species (84.09%) were correctly identified. However; 130/132 MSSA (98.48%), 64/66 MRSA (96.96%), and 44/44 CNS (100%) were correctly identified by MBT with score ≥2. 00. The principal component analysis (PCA) dendrogram generated by MBT illustrated that the tested isolates were classified into two groups of Staphylococcus species at the distance level of 600. S. aureus isolates were found to be closely related with higher peak intensities in the mass of 3,993 Da, 4,121 Da and 5,845 Da were detected in MRSA, whereas, that were lost in MSSA. CONCLUSION This study verified that MBT is an alternative powerful tool for precise identification and discrimination of Staphylococcus species.