Objectives: Aim of this study was to determine M (emm) subtypes of Streptococcus pyogenes strains isolated from asymptomatic carriers and children with pharyngitis, and to investigate the correlation between emm types, the presence of fibronectin binding protein genes, and phenotypes of antibiotic resistance. Methods: We detected and characterized emm subtypes in 59 strains of S. pyogenes isolated in Sicily (Italy) from asymptomatic carriers (29) and children with pharyngitis (30) previously characterized for the presence of prtF1 and pfbpI genes and erythromycin resistance phenotypes (Musumeci et al., Clin. Infect. Dis. 2003; 37:173-179). emm gene specific PCR and emm sequence typing were performed as described by Beall et al. (J. Med. Microbiol. 1998; 47:893-898). In addition, to confirm the relationship between emm pattern type and SOF (serum opacity factor), sof gene was detected and sequenced basing upon PCR and sequence analysis of a variable length 450-650-base PCR fragment. Results: The most frequent emm subtypes detected in isolates from pharyngitis were: emm1.0 (30.0%), emm89.0 (23.3%), emm2.0 (13.3%) and emm28.0 (10.0%). One new emm12 subtype (emm12.40) was detected. In isolates from asymptomatic carriers (enrolled from different classes of many primary schools) the most frequent emm subtypes were: emm12.0 (51.7%) and emm94.0 (10.3%); while there were no emm1.0 strains. The most significant differences between the two groups concerned the presence of the two more common emm subtypes, 1.0 (P = 0.001) and 12.0 (P < 0.001). The prtF1 and prtF2 genes were simultaneously present in 14 of 16 (87.5%) emm12.0 and 8 of 9 (88.9%) emm89.0 isolates. Correlation with phenotypes of resistance showed that 9 of 11 (81.0%) M phenotype strains belonged to emm12.0 subtype and all 3 iMLS-A phenotype strains to emm89.0. Conclusion: This study suggests that S. pyogenes emm12 and emm89 isolates, mainly positive for prtF1 and prtF2 genes, are more virulent than the others, and that emm12 isolates may have a role in the asymptomatic carrier status.
Association of group A streptococcal emm types with virulence traits and macrolide resistance
BLANDINO, Giovanna;
2010-01-01
Abstract
Objectives: Aim of this study was to determine M (emm) subtypes of Streptococcus pyogenes strains isolated from asymptomatic carriers and children with pharyngitis, and to investigate the correlation between emm types, the presence of fibronectin binding protein genes, and phenotypes of antibiotic resistance. Methods: We detected and characterized emm subtypes in 59 strains of S. pyogenes isolated in Sicily (Italy) from asymptomatic carriers (29) and children with pharyngitis (30) previously characterized for the presence of prtF1 and pfbpI genes and erythromycin resistance phenotypes (Musumeci et al., Clin. Infect. Dis. 2003; 37:173-179). emm gene specific PCR and emm sequence typing were performed as described by Beall et al. (J. Med. Microbiol. 1998; 47:893-898). In addition, to confirm the relationship between emm pattern type and SOF (serum opacity factor), sof gene was detected and sequenced basing upon PCR and sequence analysis of a variable length 450-650-base PCR fragment. Results: The most frequent emm subtypes detected in isolates from pharyngitis were: emm1.0 (30.0%), emm89.0 (23.3%), emm2.0 (13.3%) and emm28.0 (10.0%). One new emm12 subtype (emm12.40) was detected. In isolates from asymptomatic carriers (enrolled from different classes of many primary schools) the most frequent emm subtypes were: emm12.0 (51.7%) and emm94.0 (10.3%); while there were no emm1.0 strains. The most significant differences between the two groups concerned the presence of the two more common emm subtypes, 1.0 (P = 0.001) and 12.0 (P < 0.001). The prtF1 and prtF2 genes were simultaneously present in 14 of 16 (87.5%) emm12.0 and 8 of 9 (88.9%) emm89.0 isolates. Correlation with phenotypes of resistance showed that 9 of 11 (81.0%) M phenotype strains belonged to emm12.0 subtype and all 3 iMLS-A phenotype strains to emm89.0. Conclusion: This study suggests that S. pyogenes emm12 and emm89 isolates, mainly positive for prtF1 and prtF2 genes, are more virulent than the others, and that emm12 isolates may have a role in the asymptomatic carrier status.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
