Frequency and phenotypic virulence features of Streptococcus pyogenes strains isolated from throat carriage in Romanian population

Streptococcus pyogenes is a Gram-positive bacterial pathogen responsible for a wide variety of human diseases. The aim of this study was to investigate the rate of Str. pyogenes infections and to determine the virulence patterns in isolates obtained from patients diagnosed in the SYNEVO Laboratory in Bucharest, during December 2012 -April 2013. Material and methods. The strains were isolated from throat swabs, identification was performed by conventional tests and by using a Bruker Maldi-Tof analyzer. The bacterial adherence to the cellular substratum was assessed by using the adapted Cravioto's method. The expression of soluble virulence factors was assessed by inoculating the Str. pyogenes strains on enriched culture media. Results. From the total of the 10691 individuals, 560 (5.14%), were found to be Str. pyogenes carriers. All tested strains adhered to the HeLa cells exhibiting different adherence patterns. At least one of the investigated soluble virulence factors with DN-ase being the most prevalent (77.1%). was produced by the streptococcal studied strains. Conclusions. The Str. pyogenes strains isolated from throat carriage in Romanian population exhibited a high adherence capacity to epitelial cells and expressed at least one of the investigated soluble virulence factors, suggesting that Str. pyogenes possess a high variety of pathogenic features that can be correlated with the high frequency, diverse location and severity of the produced infections..