CHAPTER V 



THE DESTRUCTION OF BACTERIA 

 GENERAL CONSIDERATIONS 



No branch of bacteriology has been more fruitful in practical appli- 

 cation than that which deals with the factors which bring about the 

 destruction of microorganisms. Upon the study of this branch has 

 depended the growth and the development of modern surgery. 



The agents which affect bacteria injuriously are many, and are both 

 physical and chemical in nature. 



When a procedure completely destroys bacterial life it is spoken of as 

 sterilization or disinfection, the term disinfection being employed more 

 especially to designate the use of chemical agents. When the procedure 

 destroys vegetative forms only, leaving the more resistant spores un- 

 injured, it is spoken of as "incomplete sterilization." When an agent, 

 on the other hand, does not actually kill the microorganisms, but merely 

 inhibits their growth and multiplication, it is spoken of as an antiseptic. 

 The term deodorant is indiscriminately applied to substances which 

 mask or destroy offensive odors, and may or may not possess disinfectant 

 or antiseptic value. Some deodorants act chemically on the noxious 

 gases, destroying them. 



PHYSICAL AGENTS INJURIOUS TO BACTERIA 



The principal physical agents which may exert deleterious action 

 upon bacteria are: drying, light, electricity, and heat. 



Drying. Complete desiccation eventually destroys most of the path- 

 ogenic bacteria, yet great differences in resistance to this condition are 

 shown by various microorganisms. Ficker, 1 who has made a systematic 

 study of the influence of complete drying upon bacteria, concludes that 

 the resistance of bacteria to desiccation is influenced by the age of the 

 culture investigated, the rapidity with which the withdrawal of moisture 



1 Ficker, Zeit. f. Hyg., xxix, 1896. 

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