Chemical and physical agents are the two principal means of reducing-the number of microbes on a surface. Antiseptics, disinfectants, and ethylene oxide gas are the major chemical means of killing microorganisms on surfaces.
Heat, irradiation, and mechanical dislodgment are the primary physical means of eliminating viable organisms (Box 5-2).
General Methods of Reducing the Number of Viable Organisms from a Surface
The microbes that cause human disease include bacteria, viruses, mycobacteria, parasites. and fungi. The microbes within these, groups have variable ability to resist chemical or physical agents. The microorganisms
most resistant to elimination are bacterial endospores. Therefore in general, any method of sterilization or disinfection that kiils endospores is also capable of eliminating bacteria, viruses, mycobacteria, fungi, mold, and parasites. This concept is used in monitoring the success of disinfection and sterilization techniques.