Streptococci of the serological group C represent 9-17 % of all beta-hemolytic streptococcus strains obtained from clinical samplings in humans. They háve been isolated in patients down with invasive infections less often than in streptococci of serological groups A, B and G. The most frequently found group C streptococcus is Streptococcus dysgalactiae subsp. equisimilis. It causes mild and superficial infections, as well as serious ones - bacteremia, septicemia, streptococcal toxic shock syndrome, suppurative infections of the skin and soft tissue, necroti-sing fasciitis, pleuropulmonary and metastatically spread infections. The spectrum of diseases also includes post-streptococcal sequelae - peritonsillar abscess, acute glomerulonephritis (AGN) and reactive arthritis. The infections are either endogenous or exogenous (animal) in origin. Their manifestations are practically indiscernible from infections caused by group A streptococci. QÚy recently has there been confirmed the participation of Streptococcus constellatus subsp. pharyngis in the etiology of acute pharyngitis. Streptococcus anginosus is an important agent námely in purulent infections - abscesses appearing in various parts of the body, including the oral cavity, liver and spleen, and endocarditis. Infections caused by Streptococcus equi subsp. zooepidemicus and Streptococcus equi subsp. equi háve the character of zoonoses and are rare. Diseases caused by S. equi subsp. zooepidemicus include inflammati-ons of the upper respiratory tract, cervical lymphadenitis, pneumonia, bacteremia, endocarditis, meningitis, septicemia, septic arthritis and cellulitis. Upper respiratory tract infections may be followed by AGN. Diseases caused by S. equi subsp. equi are manifested námely by bacteremias. The remedy of choice for group C beta-hemolytic streptococci is penicillin G. All strains are sensitive to penicillin, there háve been penicillin-resistant isolates. Combined therapy with penicillin and gentamycin is recommended for treating endocarditis, meningitis, septic arthritis and bacteremia in neutropenic patients.

        Key words: group C beta-hemolytic streptococci - Streptococcus dysgalactiae subsp. equisimilis - Streptococcus constellatus subsp. pharyngis - Streptococcus anginosus - Streptococcus equi subsp. zooepidemicus -