Biologic and Immunologic Comparison of Nephritogenic and Nonnephritogenic Strains of Group A, M-Type 12 Streptococcus

Various biologic properties and certain physical and immunologic characteristics of acid-extracted M protein from nephritogenic and nonnephritogenic strains of group A, M-type 12 Streptococcus were studied. Assessments of colonial morphology, patterns of hemolysis, production of growth-inhibiting substances, resistance to antimicrobials, accumulation of starch, and M and T proteins failed to discriminate between strains isolated from patients with post-streptococcal glomerulonephritis and those from patients without this disease. In addition, two distinctly different forms of type 12 M protein were studied by the acrylamide gel electrophoresis technique. One pattern was characterized by a dominant double band with an Rf of 0.42, and the other pattern was distinguished by a proximal, densely stained, broad band. When the latter form of M protein was subjected to immunoelectrophoresis against absorbed type-specific antisera, an additional bidirectional precipitin arc was observed.