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PHENOTYPIC AND GENOTYPIC ASSESSMENT OF VIRULENCE FACTORS IN BETAHEMOLYTIC STREPTOCOCCI ISOLATED FROM KINDERGARTEN INFANTILE POPULATION, WITH OR WITHOUT CLINICAL SYMPTOMS, INCLUDING SCARLET FEVER

ION ANGHEL^1*, MARIANA CARMEN CHIFIRIUC^2*, MAGDA MITACHE³, LUMINITA MARUTESCU², ALINA GEORGIANA ANGHEL⁴, MARCELA POPA², DIANA PELINESCU², CORALIA BLEOTU⁵, VERONICA LAZAR²

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To determine some biochemical and virulence hallmarks of beta-hemolytic streptococci isolates isolated from kindergarten infantile population, with or without clinical symptoms, including scarlet fever. The isolated strains were identified by the help of conventional tests (sheep blood beta-haemolysis, bacitracin susceptibility, latex agglutination and API 20 Strep). Production of cell associated virulence factors (adhesins) and soluble enzymatic factors (haemolysins and other pore-forming toxins, proteases activity, DNA-ase and esculin hydrolysis) was assessed by inoculation of HeLa cells and respectively, specific enriched culture media containing different biochemical substrata, with bacterial inocula prepared from fresh cultures. The beta-haemolytic group A streptococci were investigated by PCR (polymerase chain reaction) for the streptococcal superantigenic toxin (speA, speB, speC, speF, speG, speH, speJ, ssa, smeZ and speI) gene profiles. All tested strains exhibited the ability of adherence to HeLa cells (with adherence indexes ranging from 35 to 100% and a predominant diffuse-aggregative pattern). The soluble virulence factors implicated in the pathogenicity of the streptococcal strains were represented by beta-haemolysins, proteases and DNA-ses. The most frequent alleles detected in GAS (Group A streptococci) strains were the chromosomally located genes speB and speF, as well as speG and ss, while the other genes were randomly present among the analyzed strains. The speA allele was detected in one of the two GCS strains. Conventional PCR techniques are important to identify streptococcal strains harboring SAg genes irrespectively of their gene expression status, these methods allowing the identification of Sag (superantigen) gene-less strains, that could be used to clarify the role of SAags in Streptococcus pyogenes infection, which is still a matter of dabate.