94 INFECTION 



the toxic products, as when portions of placenta or fetal membranes 

 are retained in the uterus after childbirth. 



The term toxemia is employed rather loosely to mean the presence 

 of any toxic material. Its use should be limited to the condition re- 

 sulting from the absorption of the poisonous substances produced by the 

 non-invasive bacteria themselves, as in diphtheria and tetanus. Septi- 

 cemia is the term applied to the presence in the body-fluids of toxic products 

 generated by the pyogenic microorganisms. 



FOCAL INFECTION 



In recent years considerable attention has been given the subject 

 of focal infection, that is, the primary focus of such systemic diseases as 

 acute rheumatic fever, endocarditis, chorea, and chronic rheumatoid 

 arthritis may be located in the head and usually in the form of alveolar 

 abscesses and acute and chronic tonsillitis and sinusitis. Foci of infection 

 may also be located in the genito-urinary and intestinal tracts and care- 

 ful bacteriologic examinations of sputa, urine, and urethral discharges 

 and exudates of synovial cavities, of excised lymph-nodes proximal to 

 the infected regions and of bits of infected muscles and tendons, have 

 often yielded results of diagnostic value and indicated the etiologic 

 relation of the focus of infection to existing systemic infection. The 

 subject is one of considerable importance and deserving of continued 

 clinical and bacteriologic investigation. An excellent review of this 

 subject based mainly upon the investigations of the Chicago School of 

 Clinicians and Bacteriologists has been recently made by Billings. 1 



MECHANISM OF INFECTION 



Since bacterial invasion is of frequent occurrence, the question 

 naturally arises, Why are not infections, both local and general, more 

 frequent? Thus abrasions of the surface epithelium are not uncommon 

 in the presence of active microorganisms; tubercle bacilli may be in- 

 spired, and typhoid bacilli may be swallowed, the altered local con- 

 ditions affording opportunity for producing infection, and yet the host 

 may escape. 



Bacterial invasion, therefore, does not necessarily mean infection, and 

 it may be stated that infection can only take place when 



(1) The microorganisms are sufficiently virulent. 



(2) When they invade the body by appropriate avenues and reach 

 susceptible tissues. 



1 Focal Infection; The Lane Medical Lectures, Appleton and Co., 1916. 





