Proteomic and molecular fingerprinting for identification and tracking of fish pathogenic Streptococcus

In this study, molecular and proteomic methods were compared with serological ones for species-specific identification and typing of S. parauberis and S. iniae isolated from fish. Slide agglutination, dot-blot, repetitive sequence-based PCR (REP-PCR) DNA fingerprinting and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) were performed. A new serotype was defined for S. parauberis isolated from turbot based on proteomic and serological results. Genus and/or species-specific protein biomarkers were found for the Streptococcus strains tested using MALDI-TOF-MS. Protein patterns specific to serotype and subserotype were also observed for S. parauberis strains. Species- and strain-specific DNA profiles were also obtained by REP-PCR. A good correlation was found between serological, proteomic and molecular methods for species differentiation and strain typing. However, the accuracy and discriminatory power of the MALDI-TOF-MS make it the most promising tool for the diagnosis of streptococcosis in fish and serotyping of bacterial fish pathogens belonging to the species S. parauberis, avoiding the use of experimental animals. Also highlights its usefulness for rapid and cost-effective routine application in veterinary laboratories.