50 BACTERIOLOGY FOR NURSES 



in the blood. Typhoid fever, pneumonia, and the 

 general pus infections known as " blood-poisoning " 

 belong to this class, the bacteria being found in the 

 blood or in special organs. 



Pycemia is a condition following profound infec- 

 tions, as septicaemia, in which many abscesses are 

 formed throughout the body. 



Secondary infections are those which gain entrance 

 to the body through the lesions produced by some 

 other organism, as typhoid fever followed by pneu- 

 monia, or measles followed by tuberculosis, or scarlet 

 fever followed by diphtheria ; diabetes is frequently 

 accompanied by pus infection of a serious character ; 

 in fact, all wasting diseases lower the resistance of the 

 body and greatly increase the susceptibility to infec- 

 tions of all kinds. 



The Defenses of the Body.^ — The unbroken skin 

 is usually impassable to bacteria, yirulent organ- 

 isins_ are o£ ten_J ound upo n the j kin of p erfectly 

 Jiealthy__gersons^where they appear to be harmless 

 unless an abrasion occurs, which affords an entrance 

 into the deeper tissues. The mucous membranes 

 would prove favorable sites for the growth of bacteria 

 were it not for the frequent removal of the mucus 

 which they secrete ; thejnouth of a healthy person 

 ' See Immunity, p. 54. 



