A 22 y.o. man complains of acute throat pain, increasing upon swallowing during 3 days. Body temperature 38, 3°C, neck lymph nodules are slightly enlarged and painful. Pharyngoscopically - tonsi-lar hyperemia, enlargement and edema, tonsils are covered by round yellow fibrinous patches around crypts openings. Beta-haemolytic streptococcus in swab analysis. What is the diagnosis?