Affiliation:
1. Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840
2. Primary Children's Medical Center, Salt Lake City, Utah 84123
Abstract
ABSTRACT
Acute rheumatic fever (ARF) and subsequent rheumatic heart disease are rare but serious sequelae of group A
Streptococcus
(GAS) infections in most western countries. Salt Lake City (SLC), Utah, and the surrounding intermountain region experienced a resurgence of ARF in 1985 which has persisted. The largest numbers of cases were encountered in 1985-1986 and in 1997-1998. Organisms with a mucoid colony phenotype when grown on blood agar plates were temporally associated with the higher incidence of ARF. To develop an understanding of the molecular population genetic structure of GAS strains associated with ARF in the SLC region, 964 mucoid and nonmucoid pharyngeal isolates recovered in SLC from 1984 to 1999 were studied by sequencing the
emm
gene. Isolates with an
emm18
allele were further characterized by sequencing the
spa
,
covR
, and
covS
genes. Peak periods of ARF were associated with GAS isolates possessing an
emm18
allele encoding the protein found in serotype M18 isolates. Among the serotype M18 isolates, the difference in the number of C repeats produced three size variants. Variation was limited in
spa
, a gene that encodes a streptococcal protective antigen, and
covR
and
covS
, genes that encode a two-component regulatory system that, when inactivated, results in a mucoid phenotype and enhanced virulence in mouse infection models. Pulsed-field gel electrophoresis showed a single restriction profile for serotype M18 organisms isolated during both peak periods of ARF. In SLC, the incidence of ARF coresurged with the occurrence of GAS serotype M18 isolates that have very restricted genetic variation.
Publisher
American Society for Microbiology
Reference31 articles.
1. Bessen, D., K. F. Jones, and V. A. Fischetti. 1989. Evidence for two distinct classes of streptococcal M protein and their relationship to rheumatic fever. J. Exp. Med.169:269-283.
2. Bessen, D. E., and V. A. Fischetti. 1990. Differentiation between two biologically distinct classes of group A streptococci by limited substitutions of amino acids within the shared region of M protein-like molecules. J. Exp. Med.172:1754-1764.
3. Bessen, D. E., L. G. Veasy, H. R. Hill, N. H. Augustine, and V. A. Fischetti. 1995. Serologic evidence for a class I group A streptococcal infection among rheumatic fever patients. J. Infect. Dis.172:1608-1611.
4. Carapetis, J. R., B. J. Currie, and J. D. Mathews. 2000. Cumulative incidence of rheumatic fever in an endemic region: a guide to the susceptibility of the population? Epidemiol. Infect.124:239-244.
5. Pathogenesis of Group A Streptococcal Infections
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