ANTISEPSIS AND STERILIZATION

During much of the nineteenth century, both the medical community and the general public believed that wound infections and fevers were caused by foul emanations, or miasmata—poisons produced by rotting animal and vegetable material, soil, and standing water that were subsequently released into the atmosphere as vapors. Sanitary reforms, sewer systems, and fresh air endeavors formed the main components of an emerging public health movement based on this understanding. In the mid-1860s, antisepsis offered a different view of infection, one based on germ theory.

Joseph Lister (1827–1912) experimented with carbolic acid dressings and continuous carbolic acid sprays during surgical operations in the mid-1860s. He reported a reduced incidence of gangrene and mortality. He eventually abandoned carbolic acid around 1890 when Koch demonstrated heat to be more effective than chemicals for sterilizing instruments, and when Ernst von Bergmann (1836–1907) achieved better results through cleaning techniques for operating rooms, instruments, patients, and surgeons.

Antisepsis is the prevention of infection by any procedure that reduces microbes on the skin or mucous membranes to a significant degree. Antiseptics are the substances used to inhibit the growth of bacteria—germicides, in contrast, are substances that kill bacteria. Initially, antisepsis protected patients from contaminating pathogens (disease-producing organisms) in the environment by preventing organisms from entering the body through a wound and by controlling the spread of contagious diseases. During the 1980s, health care agencies implemented "Universal Precautions" for all patients, indicating a shift in thinking related to the transmission of disease by blood and body fluids. With this shift, antisepsis and disinfection became important tools for protecting care providers as well as patients.

Both disinfection and sterilization reduce or eliminate pathogens through either physical or chemical processes. Sterilization is the process of destroying all microorganisms and their pathogenic products. The oldest, most efficient methods to eliminate contamination on objects or in food or water involve the use of various forms of heat: boiling, flaming (passing an object through a flame), or burning. Although burning also destroys the object, it achieves the main goal of preventing the spread of disease. Chemical processes involve the use of a variety of antiseptics and disinfectants in either liquid or gaseous states.

Typically, disinfectants are chemical substances, such as mercury bichloride or phenol solutions, that are too strong for application to body tissues. Inanimate objects that cannot withstand sterilization are soaked in disinfectant solutions for specific amounts of time, depending on the material and the susceptibility of the pathogenic organism to the solution. There are several methods of sterilization, including soaking objects in bactericidal chemical compounds, exposing objects that are heat or moisture sensitive to radioisotopes or bactericidal gases (such as ethylene oxide) or, most commonly, autoclaving objects. Autoclaves are metallic, locking containers within which equipment is exposed either to wet steam under pressure at temperatures of 120°C or higher for fifteen minutes or to dry heat at 360° to 380°C for three hours. These objects may be wrapped in cloth, paper, or certain plastics or left unwrapped. The actual exposure time and temperature varies according to the article, the potential contaminants, and the packaging used.

Cynthia Toman

(see also: Cross Infection; Nosocomial Infections; Universal Precautions )

Bibliography

Fox, Nicolas J. (1988). "Scientific Theory Choice and Social Structure: The Case of Joseph Lister's Antisepsis, Humoral Theory and Asepsis." History of Science 26:367–397.

Miller, B. F. (1997). Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, 6th edition. Philadelphia, PA: Saunders.

Porter, R. (1998). The Greatest Benefit to Mankind: A Medical History of Humanity. New York: W.W. Norton.