Comparison of serotyping, ribotyping and pulsed-field gel electrophoresis for distinguishing group A Streptococcus strains isolated in Albania.

Conventional serotyping for T antigens, rRNA gene restriction fragment length polymorphism analysis (ribotyping) and pulsed-field gel electrophoresis were compared for distinguishing among group A streptococci isolated in Albania between 1980-1982 and in 1995. A total of twelve serotypes were identified among seventy GAS strains. Ribotyping revealed eight and eleven distinct patterns after digestion with HindIII and PvuII, respectively. Twenty-three strains of serotype T12 were subdivided in 10 ribotypes and 11 strains of T2 serotype were differentiated in 5 ribotypes. By comparison, PFGE generated 37 patterns after SmaI digestion. The index of discrimination, using the Hunter-Gaston formula, was applied to assess the value of these methods for interpretation of the epidemiological data. For serotyping the value of index was 0.85. The ribotyping system revealed an ID of 0.83 when the combination HindIII and PvuII was used. This index reached 0.97 for PFGE. The methods used were useful to subtype the isolates of GAS.

Molecular subtyping of group A streptococcal strains based on virulence regulon polymorphism.

A total of 64 Streptococcus pyogenes isolates included in a previous study (Shundi et al., 2000) were further analyzed by Vir typing. Vir typing is based on restriction fragment length polymorphism (RFLP) analysis of a 4- to 8-kb pathogenicity island (vir regulon) encoding emm and other virulence genes. As all our isolates contained a single vir regulon, the stoichiometric yield of restriction fragments avoided ambiguities in interpretation of results. By using both HaeIII and HinfI restriction endonucleases to generate RFLP profiles, the 64 GAS isolates were distributed among 22 Hae- and 26 Hinf-Vir types respectively.

Streptococcal erythrogenic toxin spe A gene detection by polymerase chain reaction in strains isolated in Albania.

The presence of gene encoding erythrogenic toxin type A (spe A) was determined by the polymerase chain reaction (PCR) to target specific sequences in 72 strains of Streptococcus pyogenes representative T type strains, which were associated with scarlet fever, impetigo, tonsillitis, isolated between the years 1980-1982 and in 1995 by carriers. Isolates showed statistically significant differences in the presence of spe A. With scarlet fever the strains had a 22.22% association, with impetigo had a 8.33% association. With tonsillitis' and with carriers had a low association, 5.55% and 6.9% respectively. The analysis of the data indicated that strains with certain T type surface antigens showed a higher (such as T-1, T-2, T-5) or lower (such as T-4, T-13, T-27) tendency to contain the spe A gene were more likely to be associated with scarlet fever and impetigo than with other types of diseases.