S. pyogenes is the cause of one third of all acute pharyngitis in children and adolescents, and consequently can lead to acute rheumatic fever and acute glomerulonephritis. This bacterium causes the disease only in humans and primarily causes subclinical and clinical infections in the skin and mucous membranes of the upper respiratory tract. Pyogenic streptococcus is the most common bacterial cause of pharyngitis. Group C and G streptococci are the most common non-group A streptococci associated with pharyngitis. Among other rare pathogens we have: Arcanobacterium haemolyticum, Neisseria gonorrhoeae, Corynebacterium diphtheriae and atypical Mycoplasma pneumoniae and Chlamydophila pneumoniae. S. pyogenes is evidenced by culturing on blood agar, and is identified by evidence of A-antigen by coagglutination or sensitivity to the antibiotic bacitracin. The rapid test serves to directly demonstrate the presence of BHS-A in a throat swab using monoclonal antibodies. ASO titer or antistreptolysin titer is a serological test that indicates previous streptococcal infections and is most often used in the diagnosis of acute rheumatic fever. For the treatment of streptococcal pharyngitis are effective: penicillin, penicillins with extended spectrum of action (ampicillin or amoxicillin), clindamycin, certain cephalosporins and macrolides. Penicillin is the drug of choice recommended by all major health organizations.