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Asepsis is the state of being free from disease-causing contaminants (such as bacteria, viruses, fungi, and parasites) or, preventing contact with microorganisms. The term asepsis often refers to those practices used to promote or induce asepsis in an operative field in surgery or medicine to prevent infection. Ideally, a surgical field is "sterile," meaning it is free of all biological contaminants, not just those that can cause disease, putrefaction, or fermentation, but that is a situation that is difficult to attain, especially given the patient is often a source of infectious agents. Therefore, there is no current method to safely eliminate all of the patients' contaminants without causing significant tissue damage. However, elimination of infection is the goal of asepsis, not sterility.
The modern concept of asepsis evolved in the 19th century. Ignaz Semmelweis showed that washing the hands prior to delivery reduced puerperal fever. After the suggestion by Louis Pasteur, Joseph Lister, 1st Baron Lister introduced the use of carbolic acid as an antiseptic and reduced surgical infections rates. Lawson Tait went from antisepsis to asepsis, introducing principles and the iconic statutes that have remained valid to this day. Ernst von Bergmann introduced the autoclave, a device used for the practice of the sterilization of surgical instruments.
Today's techniques include a series of steps that complement each other. Foremost remains good hygienic practice. The procedure room is laid out according to specific guidelines, subject to regulations concerning filtering and airflow, and kept clean between surgical cases. A patient who is brought for the procedure is washed and wears a clean gown. The surgical site is washed, possibly shaved, and skin is exposed to a germicide (e.g., an iodine solution such as betadine). In turn, members of the surgical team wash hands and arms with germicidal solution. Operating surgeons and nurses wear sterile gowns and gloves. Hair is covered and a surgical mask is worn. Instruments are sterilized through autoclaving, or, if disposable, are used once. Irrigation is used in the surgical site. Suture material or xenografts have been sterilized beforehand. Dressing material is sterile. Antibiotics are often not necessary in a "clean" case, that is, a surgical procedure where no infection is apparent; however, when a case is considered "contaminated," they are usually indicated.
Dirty and biologically contaminated material is subject to regulated disposal.