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Production of broad-spectrum bacteriocin-like activity by group A streptococci of particular M-types
Abstract:
Application of a bacteriocin production (P)-typing scheme to group A streptococci has shown that approximately 10% of the tested strains inhibit the growth of all 9 indicator bacteria, an activity referred to as P-type 777. Production of such activity was found to be restricted to 14 M-serotypes and within these M-types the incidence of P-type 777 activity was very high. There was no evidence of any correlation with the T-antigenic composition of the bacteria. Investigations of the conditions for production of P-type 777 activity and of its spectrum of activity indicate that the same inhibitory substance(s) are responsible for this inhibition in the various M-types of streptococci. Group C streptococcus strain T277 produces an inhibitor which has a similar activity spectrum to that of the P-type 777 group A streptococci, but there were considerable differences in the production conditions. Whereas the group C inhibitor was particularly dependent on conditions of incubation (37 degrees C, anaerobic) the group A activity was more dependent on the composition of the test medium (source of blood agar base and blood requirement). All of the tested P-type 777 group A streptococci had identical inhibitory spectra. This was principally directed against gram-positive bacteria, including the producer strains themselves. Of interest was the occurrence of some insensitive strains in otherwise susceptible species of bacteria and the discovery of one sensitive gram-negative strain, Bacteroides intermedius. Production of P-type 777 activity does not appear to correlate with production of various streptococcal enzymes, including protease, hemolysin, DNase and amylase. Many P-type 777 strains are producers of opacity factor, another M-type-associated product of group A streptococci. It is suggested that by the combined testing of group A streptococci for P-type 777 activity and for opacity factor it would be possible to narrow the choice of M-antisera to be used for typing purposes.
Insights
Approximately 10% of group A streptococci exhibit P-type 777 activity, inhibiting all tested bacteria. This specific bacteriocin production correlates with certain M-serotypes and opacity factor, aiding in streptococcal typing.
Area of Science:
- Microbiology
- Bacteriology
- Immunology
Background:
- Bacteriocin production (P)-typing schemes are used to group streptococci.
- P-type 777 activity in group A streptococci inhibits all 9 indicator bacteria.
- This activity is linked to specific M-serotypes but not T-antigens.
Purpose of the Study:
- To characterize P-type 777 activity in group A streptococci.
- To investigate the conditions and spectrum of activity for P-type 777.
- To compare P-type 777 activity with group C streptococci and other streptococcal products.
Main Methods:
- Application of a bacteriocin production (P)-typing scheme.
- Testing of group A streptococcal strains against 9 indicator bacteria.
- Analysis of production conditions, activity spectrum, and correlation with M-serotypes, T-antigens, and enzymes.
Main Results:
- 10% of group A streptococci showed P-type 777 activity, restricted to 14 M-serotypes.
- The inhibitory substance(s) appeared consistent across M-types.
- Group C streptococcus strain T277 showed similar activity but different production conditions.
- Activity spectra were identical for P-type 777 strains, targeting Gram-positive bacteria.
- No correlation found with protease, hemolysin, DNase, or amylase production.
- Many P-type 777 strains produced opacity factor.
Conclusions:
- P-type 777 activity is a distinct characteristic of certain group A streptococcal M-serotypes.
- Combined testing for P-type 777 and opacity factor may refine M-antisera selection for typing.
- The study provides insights into bacteriocin activity and its potential use in bacterial identification.