They are germicidal, cationic detergents.  They are bactericidal against Gran positive bacteria & Gram negative bacteria & are also effective against fungi to certain pathogenic protozoa. Virus appear to be more resistant than bacteria. The two popular quats are  Zephiran, a brand mane of benzalkonium chloride & Cepacol, a brand name of cetylpyridinium chloride.Eg Cetrimide . Please visit this link;

 They are used as skin disinfectant, preservatives in ophthalmic solution,& cosmetic preparations. They are widely used for control of mos on  floors & walls of hospitals & public places. They are also used to sanitize food & beverage utensils in the restaurant & in food processing plants. 

Mode of Action:
They denature protein, interfere with glycolysis & membrane damage. They mostly damage the cytoplasmic membrane by altering the permeability. To know more visit the links below;

H). GASEOUS AGENTS:  Gases are used to sterilize heat sensitive item such as syringes, sutures, catheters, etc. The major gases used are ethylene oxide(ETO), Beta- propiolactone , formaldehyde.
  • Ethylene Oxide: It is both microbiocidal as well as sporicidal. So, ethylene oxide is also called gaseous autoclave. However, it is carcinogenic  & highly explosive. So it should be used with Freon gases or carbon dioxide.  
Uses:  To sterilize heat sensitive materials like syringes, sutures, catheters, optical instrument, artificial  heart valve.
Mode Of Action: It is believed to cause alkylating reactions with enzymes & other proteins.  Please visit this link for more detail :

  • B-propiolactone: It is occasionally used as sterilizing gas, though it is bactericidal, fungicidal, sporicidal, virucidal , it has low penetration capacity. It is carcinogenic & difficult to handle, so it is used to sterilize serum & vaccines.  please visit this link :,


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