Biofilm formation by group A Streptococci of various types and study of antibiotics effect on this process

AIM: Evaluation of the ability to form biofilms by various M, T and MT-types of group A streptococci (GAS), as well as study of the effect of various antibiotics on biofilm formation. MATERIALS AND METHOD: 43 strains of various M and T type GAS were studied. The cultures were grown in Todd-Hewitt broth with the addition of 0.5% yeast extract. Comparative evaluation of the ability to form biofilm was carried out using photometry. Benzylpenicillin, oxacillin, cepha- losporin, cefuroxime and ceftriaxone antibiotics were used at various concentrations. RESULTS: GAS differ significantly by their ability to form biofilms. The highest ability was noted in 8 strains--2M, 9M, 12M, 13M, 19M, 30M, 36M-types and 6MT type. Simultaneous introduction of GAS cultures and antibiotics into the culture well, except for ceftriaxone, resulted in growth inhibition of both plankton cells and biofilms. CONCLUSION: The ability of GAS to form biofilm depends on streptococci serotype. During simultaneous introduction of GAS with antibiotics into the well, the biofilm does not form.