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Published on: November 4, 2016
Molecular characterization of Streptococcus pyogenes isolates collected during periods of increased acute rheumatic
Lonnie J Miner1, Susan J Petheram, Judy A Daly
1Department of Pediatrics, University of Utah Health Sciences Center, Salt Lake City, UT, USA.
Background:
Salt Lake City, Utah has seen a continuing resurgence of rheumatic fever (RF) since 1985.
Methods:
emm genotyping and multilocus sequence typing of streptococcal isolates from periods of increased RF activity were performed.
Results:
Multiple genotypes were present during 1985 and 1998, two peak years of RF activity, and in 1992, a year with reduced RF activity. emm3 and emm18.1 were present in 1985 and 1998, but not in 1992. Two other emm types, 12 and L28, were significantly elevated in 1998 (a peak RF year) over 1992 (a non-peak RF year). Allelic profiles for the emm3 and emm18.1 isolates exhibited clonality.
Conclusions:
During years of increased RF activity multiple emm types, including emm18.1 and emm3, were circulating in the community. During a year of decreased RF activity, emm3 and emm18.1 genotypes were absent. The clonality of the emm3 and emm18.1 types suggests that specific clones of both types are important in the resurgence of RF during these peak years. Two other genotypes, emm12 and emmL28, may also be associated with the persistence of RF in the Salt Lake City, UT area.
Insights
Specific Streptococcus pyogenes strains, including emm3 and emm18.1, were linked to rheumatic fever (RF) resurgence in Salt Lake City during peak activity years. These strains were absent during periods of reduced RF incidence.
Area of Science:
- Infectious Diseases
- Microbiology
- Epidemiology
Background:
- Salt Lake City has experienced a persistent increase in rheumatic fever (RF) cases since 1985.
- Understanding the specific microbial factors driving RF resurgence is crucial for public health interventions.
Purpose of the Study:
- To investigate the emm genotypes of Streptococcus pyogenes associated with periods of high and low rheumatic fever activity in Salt Lake City.
- To determine if specific emm types or clones correlate with RF resurgence.
Main Methods:
- emm genotyping and multilocus sequence typing were performed on Streptococcus pyogenes isolates.
- Isolates were collected from periods of increased and decreased RF activity in Salt Lake City.
- Genotypic data was analyzed to identify correlations between emm types and RF incidence.
Main Results:
- Multiple emm genotypes were detected during peak RF years (1985, 1998) and a low-activity year (1992).
- emm3 and emm18.1 were prevalent in peak RF years but absent in the low-activity year.
- emm12 and emmL28 showed significant elevation during a peak RF year compared to a non-peak year, and emm3/emm18.1 isolates demonstrated clonality.
Conclusions:
- Specific emm genotypes, notably emm3 and emm18.1, were associated with increased rheumatic fever activity.
- The absence of emm3 and emm18.1 during low RF activity periods suggests their critical role in resurgence.
- Clonality of emm3 and emm18.1 indicates specific strains are driving RF outbreaks, with emm12 and emmL28 potentially contributing to RF persistence.
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