Microorganisms which are present naturally in human body is called normal flora. The most common microorganism is bacteria which are present in eye, intestine, skin and vagina etc. Protozoan, viruses, and fungi are not included in normal flora. The bacteria and human body have symbiotic relationship with each other in which both are getting benefit without harming each other e.g. bacteria in small intestine produce fat soluble vitamins which helps in digestion and absorption of food while human body give shelter to it. Bacteria cause pathology:
v When Overpopulated
v In Immunocompromised patients
v At Other site
Removal of the entire microorganism from any substance is called sterilization. Autoclaving is the sterilization procedure for which the Gold Standard is 121°C heated steam at 15 lb/in² for 15 min exposure of thing. Pasteurization is the sterilization of milk.