MYCIN was an early expert system developed to assist with diagnosis and treatment recommendations for bacterial infections. It is historically important in artificial intelligence because it demonstrated rule-based reasoning in a specialized medical domain.
An early backward chaining expert system that used artificial intelligence to identify bacteria causing severe infections, such as bacteremia and meningitis, and to recommend antibiotics, with the dosage adjusted for patient's body weight β the name derived from the antibiotics themselves, as many antibiotics have the suffix "-mycin". The MYCIN system was also used for the diagnosis of blood clotting diseases.