Studies on a Non-Hemolytic Streptococcus Isolated From the Respiratory Tract of Human Beings

Abstract

In the preceding paper (1) evidence was presented to show that various strains of a non-hemolytic streptococcus, designated streptococcus MG, belong to a homogeneous bacteriological group a n d t h a t the properties of this microorganism appear to characterize it as a distinct and hitherto undifferentiated microbial species. Interest in streptococcus MG was aroused because of the frequency with which strains were isolated from patients with primary atypical pneumonia and because of the development of antibodies against this microorganism in the sera of patients convalescent from the disease (2-4). In the present paper the results of studies concerning the immunological characteristics of streptococcus MG will be described in detail.Numerous attempts have been made to classify the large group of non-hemolytic streptococci by means of immunological methods. The term "non-hemolytic" will

Studies on Primary Atypical Pneumonia. Ii. Observations Concerning the Relationship of a Non-Hemolytic Streptococcus to the Disease 12

“…salivarius, type I, which is ap-parently due to antigenic similarities in the capsular polysaccharides of these two microorganisms (3 obtained during the course of the disease, a 2-fold increase in the titer of the convalescent serum was demonstrated in 47 patients, a 4-fold increase in 25, an 8-fold increase in 13, a 16-fold increase in 8, a 32-fold increase in 2, and a 64-fold increase in 1. In 3 patients, agglutinins were present in the acute-phase serum and no increase in the titer of the convalescent serum was demonstrable.…”

“…The so-called R variants obtained by this procedure no longer were capable of synthesizing demonstrable capsular polysaccharide, and failed to give a positive quellung reaction with rabbit anti-streptococcus MG serum (3). The serum of rabbits immunized with R variants was capable in high dilution of agglutinating the R variants but either failed to agglutinate encapsulated strains of streptococcus MG or agglutinated them only at very low serum dilutions.…”

“…The details of the procedure used for 'The authors are grateful to Dr. A. A. Applebaum, Toledo, Ohio, Major J. H. Dingle, M.C., A.U.S., Fort Bragg, N. C., Dr. W. S. Tillett immunization are described elsewhere (3). The immune sera thus prepared usually possessed agglutination titers of 1: 2500 or higher, and also caused definite capsular swelling of streptococcus MG.…”

“…A detailed account of the biological properties of streptococcus MG is given in a separate paper (2). It was found that there was a striking homogeneity in the properties of different strains of streptococcus MG, and that these properties made it possible to differentiate this microorganism from other non-hemolytic streptococci.…”

“…For convenience, this streptococcus will be referred to in this report as "streptococcus MG." The problem of classification of streptococcus MG is discussed in a separate paper (2).…”