title: Interference of alpha-hemolytic streptococci isolated from tonsillar surface on beta-hemolytic streptococci (Streptococcus pyogenes)--a methodological study.
abstract: The interference between alpha-streptococcal strains obtained from patients with repeated tonsillitis and a collection of group A streptococcal strains were studied. For this purpose three in vitro methods were designed and compared. The results obtained by a simple plating technique suitable for screening purposes were found to correlate well with those using more laborious techniques. In a limited scale some of the alpha- and beta-streptococcal combinations were tested under in vivo conditions using a tissue cage model allowing repeated sampling. In most instances agreement between the results of the in vitro and in vivo methods was registered. Several alpha-strains having inhibitory capacity to the majority of a collection of group A streptococci belonging to different serotypes were found, but also alpha-strains with an inhibitory activity restricted to few group A isolates within a certain serotype. Also beta-streptococcal strains with growth inhibiting activity towards some alpha-strains were found. As the methods were chosen to eliminate many of the unspecific inhibitory factors and the beta-hemolytic test strains showed a pattern of inhibition that varied for each of the reference alpha-strains the activity is most likely attributed to bacteriocin-like substances.
mesh_terms: D000293:Adolescent; D000328:Adult; D000362:Agar; D000818:Animals; D000898:Antibiosis; D002648:Child; D006801:Humans; D008875:Middle Aged; D014066:Palatine Tonsil / Q000382:microbiology*; D011817:Rabbits; D013045:Species Specificity; D013291:Streptococcus / Q000254:growth & development*; D013297:Streptococcus pyogenes / Q000254:growth & development*; D013298:Streptococcus sanguis / Q000254:growth & development*; D014069:Tonsillitis / Q000382:microbiology
chemical_list: D000362:Agar