Studies on the Hemolytic Streptococcus of Human Origin

Abstract

It could be said with little fear of contradiction that the hemolytic streptococcus presents a more hazy picture to bacteriologists and immunologists than does an organism like the pneumococcus. Its study presents many difficulties. In the first place, many strains which are pathogenic for man may show little or no primary virulence for animals. In the second place, antisera cannot be produced readily and consistently against all pathogenic strains. In the third place, although it is certain that many different types exist, typing by agglutination is full of pitfalls, both in technique and in the interpretation of results.It seemed to us that the foundation for any work on the hemolytic streptococcus was a careful study of the characteristics of the organism on first isolation from the body, and the ways in which it changed on mouse passage or culture passage; and the results of this part of the work are recorded in this first paper. We were aided in this investigation by the studies of several workers in this field, although it was sometimes difficult to correlate their descriptions of the variants of the hemolytic streptococcus with our own observations. Cowan (1) was the first to correlate cultural characteristics with virulence. She described a virulent S colony and an avirulent R colony. These variants were apparently found in stock laboratory cultures.

Asymptomatic Carriage of Group A Streptococcus Is Associated with Elimination of Capsule Production

“…Our findings are consistent with early studies that reported GAS throat isolates cultured from asymptomatic humans lack observable capsule (33,34) and were subsequently shown to produce less hyaluronic acid capsule than infecting strains of GAS (7). The identification of frameshift-inactivating mutations in the hasA or hasB genes in carrier strains provides a molecular mechanism for the early observations linking decreased capsule production and carriage.…”

“…3G). The identification of the frameshift inactivating mutation in the hasA gene in carriage strain MGAS12503 provides a mechanism for the early observations linking decreased capsule production and carriage (33,34).…”

Studies on the Pathogenicity of Group a Streptococci

“…Although the in vi~o observations of Bordet, Marchand, and WaUgren, which related virulence to phagocytosis, have been confirmed (7), phagocytic experiments performed in vitro have yielded results which are difficult to interpret for the followLug reasons: (a) the strains of streptococci studied have often been inadequately characterized in regard to their content of cellular components known to be antiphagocytic (7)(8)(9), (b) the tests have usually been performed in the presence of "normal" serum which may or may not contain "natural" opsonins (7)(8)(9)(10)(11)(12)(13), and (c) the cells used in the phagocytic tests have, with but rare exceptions, been obtained from species of hosts other than those in which the virulence has been measured (7)(8)(9)(10)(11)(12)(13). Recently Wiley and Wilson (12) have emphasized the failure of in vitro phagocytic tests, as customarily performed, to reveal phagocyte-bacterium relationships which correlate directly with streptococcal virulence.…”

Studies of Hemolytic Streptococcal Infection. Iii. The Characteristics of the Hemolytic Streptococci Isolated From Patients With Erysipelas 1

“…A small amount of sterile salt solution was injected into the edge of the lesion and, after waiting for several minutes, material was then aspirated and placed in blood broth. Twenty-two strains were isolated and studied, according to the following standard methods: sugar fermentation with one per cent lactose, mannite, salicin, trehalose, and sorbital, final pH in dextrose broth, the reduction of methylene blue, the hydrolysis of sodium hippurate, hemolysis on blood agar plates (4); the type of colony, on surface plates of neopeptone agar (5); the erythrogenic toxin production, the serological classification,2 and the fibrinolysin production. Toxin-antitoxin neutralization tests were carried out when the presence of toxin was found.…”