Question

Directions: Fill out the table below with the necessary information for each of the chemical methods listed. Give an example for each chemical disinfectant, and outline some general characteristics about it (specific mode of action, what is used for, any other information in the slides or text book) Chemical method SterilizationExample Characteristies Phenols Alcohol Oxidizing agents Heavy metals formaldehydes

Answer 1

Disinfection is the process of removing harmful microorganism where as sterilisaation is the process by which all the microorganisms including spores are removed.

Phenols: Phenols are disinfectants which eliminate harmful microorganisms from surfaces. It is one of the oldest disinfectant. Dettol, mouth washes, are examples.At lower concentrations, it act as bacteriostatic where as higher concentration it act as bacteriocidal activity. It is a potential irritant and corrosive.

Alcohol: It is a disinfectant. It kills pathogenic microorganisms including bacteria. Ethanol and isopropyl alcohol can be used as disinfectant. Alcohols are good disinfectant as they evaporate very fast and leave no residue behind. They dissolve easily in lipids so can act against lipid wrapped viral cells and can be used against viruses such as HIV and hepatitis A. It works by denaturing proteins and by dissolving lipids it destroys bacterial and viral cells.

Oxidising agents: They are disinfectants, chlorine and oxygen are strong disinfectants, which is found in common household bleach (sodium hypochlorite solution), calcium hypochlorite, elctrolyzed water are some examples. they work by oxidizing of cell membrane which leads to lysis of cell lysis and death.

Heavy metals: It is the first chemical disinfectant used, salts of mercury, silverlactate, mercuric chloride and mercurous chloride are some examples. They act by binding to proteins, thus inhibiting the enzymatic activity of proteins. They are non-selective toxic to microorganisms.They bioaccumulate in humans, so higher concentrations are harmful.

Formaldehydes: Disinfectants and strelilant, included in the group aldehyde, effective against fungus and spores. Paraformaldehyde is an example which is a solid polymer of formaldehyde. It has sporocidal activity. It is suspected to have carcinogenic activity. it act by alkylating the proteins of microorganisms.