DNA fingerprints of Streptococcus pyogenes are M type specific.

DNA from group A streptococci of various M and T types was cleaved with endonucleases to produce a DNA fingerprint. Comparison of DNA fingerprints proved to be a very useful tool for studying the epidemiology of isolates from various outbreaks of streptococcal disease. Patterns of DNA fragments from HindIII digests of samples of total DNA were conserved among strains of the same M serotype yet were easily distinguished from those of different M serotypes. Different M types were associated with specific restriction enzyme profiles. DNA fingerprints of strains of the same M type were stable enough to establish a clonal relationship between strains obtained from an isolated outbreak of disease or strains endogenous to people geographically isolated by continent. Strains of the same serotype from different continents had very similar, but distinguishable, restriction profiles. Those strains unable to be typed with standard typing sera were also amenable to comparison because they yielded unique fingerprints.