Physical and Chemical Control of Microorganisms

Physical and Chemical Control of Microorganisms - Physical...

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Physical and Chemical Control of Microorganisms I. In most medical settings, the control of microorganisms is of paramount concern. Decontamination refers to the destruction or removal of microorganisms from instruments, materials, body surfaces, etc. Many agents and procedures have been developed to accomplish this end. It is imperative that you, as a medical professional, understand the modes of action, level of activity and other factors which influence the effectiveness of these procedures and agents. A. Generally, decontamination involves physical and/or chemical agents. Physical agents include high temperature, radiation, filtration or cavitating sound waves. A myriad of chemical decontamination agents exists. For the most part, they are substances that react with and thus alter some important molecular component of the cell. B. Microorganisms are not uniformly affected by physical and chemical decontamination. Susceptibility to the effects of physical and chemical agents depends upon the type of microorganism and at what stage in the microorganism’s lifecycle they are exposed to the agent. When choosing and applying a method of decontaminating materials, it is important that you understand what type of organism is being targeted and the relative resistance of that organism. 1. The target with the highest resistance is the bacterial endospores. Endospores are ubiquitous in the environment. Many bacteria found in the soil are capable of forming these structures. Introduced into deep wounds or during surgical procedures, these spores can cause severe problems. Thus surgical equipment and other materials used in invasive procedures need to be decontaminated in such a way as to destroy these agents. 2. Targets with the moderate resistance include protist cysts, sexual fungal spores, nonenveloped viruses (many enteric viruses including those responsible for polio, Hepatitis A and Hepatitis E), Mycobacterium tuberculosis, Staphylococcus aureus and members of the genus Pseudomonas. 3. Targets with the least resistance include vegetative cells of most microbes, enveloped viruses (including those viruses responsible for AIDS and Hepatitis B), and asexual fungal spores.
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C. There are several terms that have precise meanings. When these terms are used in a product description or as part of procedural instructions it is important that you are aware of these precise meanings. 1. Sterilization refers to any process that destroys or removes all infectious organisms including endospores and viruses. 2. Disinfection refers to any physical process or application of any chemical that will kill the growing ( vegetative ) microbial cells. These processes need not kill or inactivate endospores. A disinfectant is a chemical capable of killing microbial cells. It should be understood that if a chemical is referred to as a disinfectant, it is to be used on inanimate objects and not to be used on body surfaces. 3.
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Physical and Chemical Control of Microorganisms - Physical...

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