Microbiology

Microbiology Study Guide

©2018 of 132 Cold temperatures by way of refrigeration to control the growth of microbes is another control method. Additionally, substances subjected to gamma or x-rays, allow the microbes to be controlled using radiation. Chemical Methods of Control The aim of chemical methods is to remove pathogens from substances or to limit microbes to a safe level. It should be noted that chemical methods do not facilitate sterilization. One of the popular ways to treat substances without damaging them is through the use of antiseptic or disinfectant. Different antiseptic and disinfectants should be tested in order to learn their effectiveness. One such test is the phenol coefficient test, which helps test the effectiveness of eliminating bacteria species, like staphylococcus aureus and salmonella Typhi. In this test, different dilutions of chemical agents are tested against similar dilutions of bacteria and phenol. The phenol coefficient is then studied and if the phenol coefficient is more than one, it indicates that the chemical agent is more effective than the phenol and vice versa. Another test is the in-use test. In this test, different dilutions of the chemical agent are tested against the test bacteria on the likely infectious substance. One of the popular chemicals used is phenol for the purpose of disinfection. It is the ideal chemical used in the preparation of disinfectants and antiseptics. Further, one of the derivatives of phenol, phenolic, is used in preparing disinfectants and antiseptics. Phenolics have the ability to cause damage to the membranes of the cell, and also make the enzymes of the organisms inactivate. Finally, the proteins are denatured and kill the organisms. They include cresols, such as Lysol, as well as several bisphenols, such as hexachlorophene, which is particularly effective against staphylococci. Halogens are oxidizing agents that include iodine and chlorine. Betadine (povidone–iodine) is used for cuts and wounds and to prep skin prior to surgery. A patient should be asked if there is an iodine or shellfish allergy before using betadine. Chlorine is another chemical agent that has the ability to unite with protein substances of the organism. Chlorine is used as sodium hypochlorite and is mostly used as a disinfectant in many industries, including restaurants, dairies, and slaughterhouses. Another chemical that can be used to eliminate bacteria and fungi is alcohol. It should be noted that alcohols are not successful for controlling bacterial spores. A common alcohol used to control microbes is ethyl alcohol, or ethanol, of 70 percent. Another alcohol used as an antiseptic and disinfectant is isopropyl alcohol. Heavy metals are also known to possess antimicrobial capabilities. Heavy metals are fused with sulfhydryl groups or cellular proteins in order to act as antimicrobials. For instance, the species of N isseria gonorrhea is eliminated with the help of silver nitrate to prevent and cure infection from the eyes of newborns. Achieve Page 45