70 MICROBIOLOGY 



Disinfection. Disinfection 1 is the destruction of all in- 

 fecting organisms such as bacteria, fungi and protozoa, but 

 not necessarily all of the bacteria present. When applied to 

 the disinfection of cars or stables in which animals suffer- 

 ing from protozoan diseases such as Texas fever have been 

 kept it implies the destruction of the insect which carries the 

 microorganism. 



Disinfection has a wide range of application. It is used 

 by the surgeon to prepare the field of operation, his hands, 

 instruments, and dressings and by the practitioner or the sani- 

 tarian in the cleansing of cars, stables and pens in which 

 animals suffering from infectious diseases have been kept. 



A large amount of work has been done to determine the 

 exact germicidal value of many chemicals as well as the 

 rapidity of the action of such natural germ destroyers as sun- 

 light and drying. The recorded results are not uniform. A 

 study of the germicidal action of various substances on dif- 

 ferent species of bacteria requires a careful consideration of 

 the following facts: (1) the variation in the vital resisting 

 power of different species or organisms; (2) the resisting 

 power of the same species varies under different conditions 

 such as the young actively growing cultures and old cultures ; 

 (3) the medium in which the bacteria exist influences to a 

 considerable extent the action of the disinfectants; (4) the 

 temperature under which the disinfectant acts influences the 

 rapidity and certainty of its action ; and (5) the inhibiting or 

 antiseptic action" of the disinfectant must not be confused 

 with germicidal action. 



There is often confusion in the use of certain terms re- 

 ferring to the prevention of growth and the destruction of 



1 For a more extended study of the various disinfectants and 

 their application, the student is referred to the following list of 

 works on this subject in which will be found many references to 

 specific tests and studies. 



S. Rideal, Disinfection and Disinfectants, London. 



A. G. Young, Disinfectants and Disinfection, Augusta. 



M. J. Rosenau, Disinfection and Disinfectants, Philadelphia. 



H. M. Bracken, Disinfection and Disinfectants, Chicago. 



