Development of a new epidemiological method using patterns of exoproteins secreted from bacteria

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Discrimination of each strain of bacteria such as Staphylococcus aureus and group A streptococcus (GAS) is helpful for tracing a pathogenic strain and prevention of nosocomial infections. Although DNA-based typings have been generally used as epidemiological methods for discrimination, we developed two dimensional electrophoretic (2-DE) analysis of exoproteins secreted from bacteria as a new epidemiological method and we found that this method was well applicable for the discrimination of S.aureus and GAS strains. The conditions of culture, growth and extraction of exoproteins were identified to have reproducible results. The major results of this study were as follows ; the best condition was that exoproteins were extracted from early stationary culture with TCA and were quickly applied on 2-DE ; high degree of variety was observed in the 2-DE patterns of exoproteins in S.aureus and GAS ; spots of more than 100 exoproteins of S.aureus and 20 of GAS were identified by the determination of N-terminal amino acid sequences ; a specific spot pattern was identified for each coagulase type of MRSA and variation of the spots of super antigens were observed among the strains belonging to the same coagulase type ; a correlation was observed between the spot patterns and M antigen types in GAS strains ; the MRSA strains that caused NTED and SSSS showed unique toxin production patterns, respectively, observed by 2-DE ; we have accumulated 2-DE patterns of more number of strains that would be helpful for the construction of a 2-DE database of exoproteins.