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Isolation of Streptococcus pyogenes in individuals with pharyngotonsillitis and antimicrobial susceptibility testing

AIM: We investigate the occurrence of Streptococcus pyogenes in individuals with pharyngotonsillitis that spontaneously sought attendance in drugstores or in health units. STUDY DESIGN: Longitudinal cohorte. MATERIAL AND METHOD: Samples from oropharynx of 58 individuals were collected with swab and tongue depressor and inoculated on sheep blood agar plates. At the moment the samples were collected, none of the individuals was under treatment with antibiotics. The presumptive identification of S. pyogenes was made by the susceptibility test to bacitracin and confirmed by the serological grouping through the extraction of the group-specific carbohydrate "C" antigen. RESULTS: From the 58 samples of oropharynx analyzed, 32 (55.2%) were from individuals assisted in drugstores and 26 (44.8%) were obtained from those that sought health units. A total of 15 (25.9%) samples presented positive culture for S. pyogenes, being most of the strains (9/15, 60%) coming from individuals assisted in drugstores. Streptococcus pyogenes was isolated in 33.3% (11/33) of the individuals from zero to 15 years of age and in 16% (4/25) of those over 15. The strains were susceptible to all the antimicrobial agents tested. CONCLUSION: The results of the present study emphasize the importance of the bacteriological diagnosis in the proper treatment for the streptococcal pharyngotonsillitis that determine the prevention of the supurative or non supurative complications and the eradication of the microorganism of the oropharynx.

Streptococcus pyogenes; pharyngotonsillitis; streptococcal infection


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