Abstract

PEDRAZA-AVILES, Alberto González et al. Antimicrobial sensitivity and typing of Streptococcus pyogenes strains isolated during a scarlet fever outbreak. Salud pública Méx [online]. 2002, vol.44, n.5, pp.437-441. ISSN 0036-3634.

Objective. To evaluate the in vitro activities of 13 antimicrobial agents against 47 group A Streptococcus pyogenes (GAS) strains, and to determine the presence of genes encoding streptococcal pyrogenic exotoxin A (SpeA) and the M¾protein serotypes. Materials and Methods. A cross-sectional study was conducted at Centro de Salud Dr. José Castro Villagrana, during a scarlet fever outbreak occurring between December 1999 and January 2000, among 137 children at Colegio Espíritu de América. Minimum Inhibitory Concentrations (MICs) were obtained by the semiautomated microdilution method. Automated DNA sequencing was used for analysis of sequence variation in genes encoding the M protein, and SpeA. Results. All strains were sensitive to betalactams and clindamycin. Six (12.7%) were resistant to erythromycin. The M2 type was the most frequently isolated GAS (27); almost all (96%) bacteria with the SpeA gene had the gene encoding the M2 protein. Conclusions. The recent resurgence of GAS infections calls for molecular epidemiology research and studies on the sensitivity to macrolides and beta-lactams.

Keywords : scarlet fever; Streptococcus pyogenes; M-serotype; streptococcal pyrogenic exotoxin A; susceptibility; Mexico.

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