[Resistance Rates and Phenotypic Characterization of Streptococcus Pyogenes in a Paediatric Population in Northern Spain (2005-2015)]

Objective: Streptococcus pyogenes is a significant cause of bacterial infections in children. The aim of the study is to analyse resistance rates and phenotypes of S. pyogenes isolates in a paediatric population in Northern Spain over the last 11 years.

Methods: Descriptive retrospective study of S. pyogenes isolates from paediatric patients between 2005 and 2015 in a region of Asturias (Spain). Resistance rates and changes in erythromycin resistance phenotypes in two time periods (2005-2009 and 2010-2015) were studied.

Results: A total of 1,794 S. pyogenes isolates were registered (70% from 2005 to 2009). 87.5% were obtained from pharyngeal swabs and 0.2% from blood cultures. Resistance rates to tetracycline (8.8% to 4.3%, p=0.02), erythromycin (22% to 9.3%, p<0.01) and clindamycin (6% to 1.7%, p<0.01) decreased between the two study periods. A reduction in erythromycin-resistant isolates with the MLSB phenotype was observed.

Conclusions: A decrease in S. pyogenes resistance rates to erythromycin and clindamycin and a change in the erythromycin resistance phenotype were observed along the study period.