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Changes in the pattern of infection caused by Streptococcus pyogenes
1Division of Hospital Infection, Central Public Health Laboratory, London.
Abstract:
The distribution of T- and M-protein antigens was determined in 12,469 cultures of Streptococcus pyogenes sent to a reference laboratory. Of these 7232 (58%) were isolates from hospital patients, 249 (2%) from hospital staff and 4988 (40%) from the community. The survey extended from January 1980 to June 1987. During this time the numbers of isolates of M-types 6, 49 and 81 rose then fell, being replaced by types 1, 3 and 28. The proportion of isolates of M-types 4 and 12 remained constant. Few strains were received from cases of nephritis or rheumatic fever but there has been an increase in the number of strains from serious infections and deaths. Forty-four of the 55 (80%) strains received since 1985 from fatal infections have belonged to M-type 1. All other strains, bar two, received from fatal infections in those years belonged to M-type 3. Representatives of M-type 1 were also associated with erysipelas. Types 3 and 4 predominated among the isolates from scarlet fever, types 1, 4, 12 and 49 from nephritis, types 49 and 81 from skin infections in meat workers and type 28 in cases of puerperal sepsis. The M-typability rate was 97% but new M antigens await definition among strains causing pyoderma.
Insights
Streptococcus pyogenes M-types shifted significantly between 1980-1987, with types 1 and 3 becoming dominant in severe infections. This study tracked M-protein antigen distribution in over 12,000 isolates.
Area of Science:
- Microbiology
- Epidemiology
- Immunology
Background:
- Streptococcus pyogenes (Group A Streptococcus) is a significant human pathogen.
- M-protein typing is crucial for understanding serotype distribution and epidemiology.
- Reference laboratories play a key role in national surveillance of bacterial pathogens.
Purpose of the Study:
- To analyze the distribution of Streptococcus pyogenes M-types over a 7.5-year period.
- To identify trends in M-type prevalence associated with different clinical manifestations.
- To monitor changes in serotype dominance in response to potential epidemiological shifts.
Main Methods:
- Analysis of 12,469 Streptococcus pyogenes isolates submitted to a reference laboratory from January 1980 to June 1987.
- M-protein antigen typing of isolates.
- Correlation of M-type with patient source (hospital, staff, community) and clinical outcome (nephritis, rheumatic fever, serious infections, deaths, scarlet fever, erysipelas, puerperal sepsis, pyoderma).
Main Results:
- A shift in M-type prevalence was observed, with types 6, 49, and 81 declining and types 1, 3, and 28 increasing.
- M-types 4 and 12 remained stable in prevalence.
- M-type 1 was strongly associated with fatal infections (80% of fatal cases since 1985) and erysipelas.
- M-type 3 was also associated with fatal infections.
- Specific M-types predominated in scarlet fever (3, 4), nephritis (1, 4, 12, 49), skin infections (49, 81), and puerperal sepsis (28).
- The M-typability rate was high at 97%.
Conclusions:
- Significant epidemiological shifts in Streptococcus pyogenes M-types occurred during the study period.
- Certain M-types, particularly M-type 1 and M-type 3, are increasingly associated with severe and fatal infections.
- Ongoing surveillance and characterization of M-antigens are necessary, especially for strains causing pyoderma.