Medical microbiology is a discipline of medicine concerned with the prevention, diagnosis, and treatment of infectious diseases. It is a broad subset of microbiology that is applied to medicine. Furthermore, this branch of science investigates diverse clinical applications of microorganisms for health enhancement. Infectious disease is caused by four types of microorganisms: bacteria, fungi, parasites, and viruses, as well as one type of infectious protein termed prion. Medical microbiology is the study of bacteria' nature, distribution, and activity, as well as how they impact human health and well-being, notably as infection agents. Medical microbiologists assist in the prevention, diagnosis, and treatment of many diseases caused by microbes and supervise their work (viruses, fungi and parasites).