Emm4 isolates are associated with pharyngitis in children (10,11); these isolates are entirely acapsular
, a phenotype linked to enhanced adhesion to surfaces (12).
Three strains with varying degrees of encapsulation were used in this study: a highly encapsulated strain M781; strain COHl with medium encapsulation; and an acapsular
mutant strain COHl-13.
Thus, virulent capsular strains were phagocytosed by and replicated in Acanthamoeba castellanii, leading to amoebal death, while the nonvirulent acapsular
strains were killed (11).