The use of epidemiological typing
method allows for the differentiation of individual strains of group A streptococci (GAS, Streptococcus pyogenes) of different origin. This method is important in determining the genetic relationships between microorganisms in organized groups as teaching classes and military units. The objectives of the study are to define the proportion of beta-hemolytic streptococci (BHS) in the etiology of acute tonsillopharyngitis, to carry out an epidemiological typing of GAS strains and to determine their antimicrobial susceptibility. During the period between October 2010 – January 2012 a prospective study was conducted in Pleven. A total of 934 throat swabs from patients with tonsillopharyngitis were examined. Lancefield group of the isolated streptococci was determined using the latex agglutination test (Slidex Strepto Plus, Company BioMerieux, France). M- and T -serotype identification and testing for production of serum opacity factor (SOF) were carried out. The observed relative proportion of the isolated BHS was 11.88%, from which GAS – 10.39%, GCS – 0.86% and GGS – 0.64%.
Performed serotyping of GAS showed circulation of seventeen different M- serotypes, dominated by the M25 (23.71%), M12 (11.34%), M8 (11.34%) and M6 (10.31%). The study of antibiotic sensitivity showed a low level of macrolide resistance (2.06%). Lastly, the accurate classification of GAS strains is essential for epidemiological studies and for future vaccine development.
Group A streptococci (GAS, Streptococcus pyogenes), M- serotype, T -serotype, serum opacity factor (SOF).