Epidemiology and Infection

Research Article

Clonal diversity of Streptococcus pyogenes within some M-types revealed by multilocus enzyme electrophoresis

A. M. Haasea1, A. Meldera1, J. D. Mathewsa1, D. J. Kempa1 and M. Adamsa2

a1 Menzies School of Health Research, PO Box 41096, Darwin NT 0811, Australia

a2 Evolutionary Biology Unit, South Australian Museum, North Terrace, Adelaide SA 5000, Australia


Twenty-two reference isolates and 30 local isolates of group A Streptococci were classified into 36 electrophoretic types (ET) on the basis of allozyme variation at 27 enzyme loci. Local isolates were characterized by a high frequency of M-non typable strains. M-type and ET were more closely associated in local isolates from an endemically-infected population; nevertheless, amongst the local isolates there were also strains of the same ET type with different M-types. A possible explanation is that genetic exchange between strains may introduce different M-types into strains of defined ET when these are exposed to strong selection in the presence of heavy loads of infection.

In contrast to the reported clustering of strains associated with toxic shock-like syndrome into two closely related ET clones, we found no relationship of ET phenotype to acute poststreptococcal glomerulonephritis or rheumatic fever.

(Accepted July 04 1994)