[Antimicrobial resistance characteristics of clinical isolates of Streptococcus pyogenes].
OBJECTIVE
To determine the antibiotic susceptibility of recent isolates of Streptococcus pyogenes and to evaluate the prevalence of macrolide-resistant phenotypes.


METHODS
In 1999, we conducted a cross-sectional study at Mexico Children's Hospital "Federico Gomez", to analyze one hundred strains of S. pyogenes isolated from 1992 to 1998, in children with uncomplicated pharyngotonsillitis. Strains were frozen at the bacteriology lab until they were analyzed. Strains were tested for susceptibility against some beta-lactams, macrolides and clindamycin. Double-disk testing was carried out to evaluate erythromycin-resistant phenotypes. Data are presented using central tendency measures.


RESULTS
All tested strains were not resistant to beta-lactams and clindamycin; 16% of the strains were resistant to macrolides and all of them belonged to phenotype M.


CONCLUSIONS
Susceptibility testing is recommended to identify possible changes in antibiotic resistance to streptococci.
Departamento de Infectología, Hospital Infantil de México Federico Gómez, México, D.F., México. hospdirg@prodigy.net.mx
R S
RS
Rodríguez
E
E
Calderón-Jaimes
D
D
Gómez-Barreto
L E
LE
Espinosa-de los Monteros
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003430:Cross-Sectional Studies; D004352:Drug Resistance, Microbial; D006801:Humans; D018942:Macrolides; D010641:Phenotype; D013297:Streptococcus pyogenes / Q000145:classification / Q000187:drug effects* / Q000235:genetics
D000900:Anti-Bacterial Agents; D018942:Macrolides