STERILIZATION AND DISINFECTION 71. 



bacteria. It is important, therefore, to have clearly in mind 

 the following terms and their definitions. 



Antiseptic. An antiseptic is a chemical substance which 

 inhibits the multiplication of bacteria but does not neces- 

 sarily kill the individual bacteria present. Most if not all' 

 disinfectants in solutions too weak to disinfect act as anti- 

 septics. 



Germicide. A germicide is a chemical substance or- 

 physical agent that will kill microorganisms. 



Asepsis. A substance is aseptic when it is free from? 

 pathogenic or septic bacteria. An aseptic operation, for in- 

 stance, means that the operation is performed in the absence- 

 of infecting bacteria, that is, after proper disinfection of the- 

 field of operation, the hands of the operator and the steriliza- 

 tion of the instruments and dressings. 



Deodorant. Deodorants are substances which have the^ 

 property of absorbing the unpleasant odors that are emitted 

 from matter undergoing decomposition. These substances 

 must not be mistaken for true disinfectants. 



Disinfectants. A large number of substances have been 

 used as disinfectants. In the choice of a disinfectant several 

 factors are to be considered. (1) In regard to the disinfec- 

 tant itself. It is important to choose those agents that are- 

 stable and uniform such for example as acids, alcohols or- 

 stable chemical substances such as corrosive sublimate. Certain 

 of the compounds of substances in themselves valuable are 

 found not to be uniform in their germicidal action. (2) The 

 effect upon the substance to be disinfected. Here great care 

 is to be exercised. Mercuric chloride so highly recommended 

 in surgery because of its non-irritating properties and reli- 

 ability can not be used to disinfect instruments or metal 

 articles because of its corrosive nature. (3) Facility of use 

 and cost. After the reliability of the germicidal action and 

 effect upon the objects to be disinfected are determined, a 

 further choice lies in the facility with which it can be applied' 

 and its cost. In practical disinfection, one must employ solu- 

 tions stronger than the minimum strength found to be germi- 



