![](/olcweb/styles/shared/spacer.gif) | ![](/sites/dl/free/0072320427/title/cover_image.JPG) Foundations in Microbiology, 4/e Kathleen Park Talaro,
Pasadena City College Arthur Talaro
Physical and Chemical Control of Microbes
Chapter Overview- The control of microbes in the environment, on the body, and in products is a constant concern of health care and industry.
- Control measures known as antimicrobial techniques use physical and chemical agents to target contaminants and other undesirable microbes.
- Antimicrobial control methods sterilize, disinfect, antisepticize, and sanitize materials as a means of preventing infection, spoilage, and other harmful microbial activities.
- Antimicrobial agents are designed to destroy, inhibit, or remove microbes.
- Microbes exhibit wide degrees of resistance to antimicrobial agents and require a variety of methods to control them.
- Factors that affect the action of antimicrobial methods are time, temperature, type of agent, microbial load, types of microbes, and the nature of the material being treated.
- Microbicidal agents kill microbes by causing irreversible damage to some part of the microbe, thereby permanently preventing it from reproducing.
- Microbistatic agents stop microbes from reproducing, but not permanently.
- Mechanical agents physically remove microbes from materials, but do not necessarily kill or inhibit them.
- Antimicrobial agents damage microbes by disrupting structure (cell wall, cell membrane), altering proteins, stopping synthesis, and inactivating genetic material.
- Heat is the most important agent in controlling microorganisms; it can be delivered in either moist or dry form.
- Methods that use heat include steam sterilization, pasteurization, and dry ovens.
- Radiation exposes materials to high-energy waves and particles that can penetrate microbes. Examples are ionizing and ultraviolet radiation.
- Chemical solutions may be used as disinfectants, sterilants, antiseptics, cleaners, and preservatives.
- The major classes of antimicrobial chemicals include halogens (iodine and chlorine compounds), alcohols, phenolics, peroxides, heavy metals, detergents, aldehydes, and gases.
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