Diphtheria, Tetanus, and Pertussis are serious bacterial infections that can affect children. Diphtheria is caused by Corynebacterium diphtheriae, leading to a thick coating in the throat and potential breathing issues. Tetanus, also known as lockjaw, is caused by Clostridium tetani and leads to severe muscle spasms. Pertussis, or whooping cough, is caused by Bordetella pertussis and results in severe coughing fits.