Streptococcus pyogenes
Up to 15% of acute pharyngitis cases may be caused by bacteria, most commonly "Streptococcus pyogenes", a group A streptococcus in streptococcal pharyngitis ("strep throat"). Other bacterial causes are "Streptococcus pneumoniae", "Haemophilus influenzae", "Corynebacterium diphtheriae", "Bordetella pertussis", and "Bacillus anthracis".