Characterization of group A Streptococcus strains recovered from Mexican children with pharyngitis by automated DNA sequencing of virulence-related genes: unexpectedly large variation in the gene (sic) encoding a complement-inhibiting protein.
Sequence variation was studied in several target genes in 54 strains of group A Streptococcus (GAS) cultured from children with pharyngitis in Mexico City. Although 16 distinct emm alleles were identified, only 4 had not been previously described. Virtually all bacteria (31 of 33 [94%] with the streptococcal pyrogenic exotoxin gene (speA) had emm1-related, emm3, or emm6 alleles. The gene (sic) encoding an extracellular GAS protein that inhibits complement function was unusually variable among isolates with the emm1 family of alleles, with a total of seven variants identified. The data suggest that many GAS strains infecting Mexican children are genetically similar to organisms commonly encountered in the United States and western Europe. Sequence variation in the sic gene is useful for rapid differentiation among GAS isolates with the emm1 family of alleles.
Mejia
L M
LM
Departamento de Salud Pública, Facultad de Medicina, Universidad Nacional Autónoma de México, D.F.
Stockbauer
K E
KE
Pan
X
X
Cravioto
A
A
Musser
J M
JM
D000595:Amino Acid Sequence; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002352:Carrier Proteins; D002648:Child; D003546:Cysteine Endopeptidases / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D005098:Exotoxins / Q000235:genetics; D005798:Genes, Bacterial; D014644:Genetic Variation; D006801:Humans; D008565:Membrane Proteins; D008800:Mexico / Q000453:epidemiology; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010612:Pharyngitis / Q000453:epidemiology / Q000382:microbiology*; D013290:Streptococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000235:genetics* / Q000302:isolation & purification* / Q000472:pathogenicity; D014774:Virulence / Q000235:genetics
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D005098:Exotoxins; D008565:Membrane Proteins; C097739:SIC protein, Streptococcus; C117980:SpeA protein, Streptococcus pyogenes; C027951:erythrogenic toxin; C014689:streptococcal M protein; D003546:Cysteine Endopeptidases; C042477:streptopain