Role of proteinase in the formation of inhibitory levels of hematin by group A streptococcus cultures on blood-containing media.

Group A streptococci were tested for proteinase production and for the possible relationship of this production to the generation of bacteriocinlike inhibitor activity. Of 126 strains tested, 83% were positive for proteinase, and a similar distribution was found among strains isolated in association with rheumatic fever (89%) and nephritis (94%) and from uncomplicated acute infections (78%). Although application of an inhibitor production (P) typing scheme demonstrated a variety of P types, all of the proteinase-positive strains produced inhibitory activity and over 65% of these strains were P type 204. It was shown that hematin was responsible for this P type 204 activity and that it was produced only by actively proteolytic strains when grown on a hemoglobin-containing medium. Conditions optimizing proteinase production (anaerobic incubation at 37 degrees C on a test medium prepared from Columbia agar base [GIBCO Laboratories, Grand Island, N.Y.]) increased P type 204 activity. Interference with proteinase activity either by growth of the cultures at an alkaline pH or by incorporation of sub-growth inhibitory concentrations of either iodoacetic acid or lincomycin into the medium prevented production of P type 204 activity. Whether significant conversion of hemoglobin to hematin occurs in vivo and the possible implications of this conversion with regard to the pathogenesis of group A streptococcal infections remain to be determined.