190 A MANUAL OF BACTERIOLOGY 



regarded as a solution containing a variable amount of the anti- 

 toxic or anti-microbic constituent, and for therapeutic use its 

 strength must be ascertained, and is for convenience described in 

 arbitrary units. 



The dose of antitoxin is dependent upon the gravity of the 

 disease, and not on the age of the patient, for evidently just as 

 much toxin may be formed in a child as in an adult. The anti- 

 toxins are strictly specific ; diphtheria antitoxin, for example, has 

 not the slightest influence in tetanus. 



To obtain an immediate reaction to antitoxin it should be 

 administered intra-venously. A subcutaneous injection may not 

 be completely absorbed in less than thirty-six hours, an intra- 

 muscular injection is much more rapidly absorbed. 



In cases of mixed infection, e.g. where diphtheria bacilli are 

 associated with streptococci or staphylococci, the diphtheria anti- 

 toxin will have no influence on the streptococcic or staphylococcic 

 infection. 



The complications and accidents of antitoxin treatment are 

 few and usually unimportant. Abscess and other local troubles 

 at the seat of inoculation should not occur if proper antiseptic 

 precautions be taken. Urticaria or other rashes and joint pains, 

 sometimes with pyrexia, are by far the most troublesome com- 

 plications, constituting the " serum disease." These are due 

 to the injection of foreign serum, and not to the antitoxin, for 

 the serum of an untreated horse produces a like effect. Eepeated 

 injections of serum at short intervals may be continued for a 

 long period without inducing more disturbance than that caused 

 by one or two or a few injections, but if twelve days or more elapse 

 between two injections a condition of " supersensitation," due 

 to anaphylaxis, is liable to ensue (see p. 197). This consists in 

 the rapid appearance of rashes, joint pains, pyrexia, etc., or even 

 of grave symptoms, faintness, vomiting, dyspnoea, convulsions, 

 collapse, etc. This is, however, preventable (see p. 204). 



Anti-sera may be used as prophylactics, but the immunity 

 produced by them does not last more than three weeks. 



Various hypotheses have been advanced to explain 

 the manner in which toxin is neutralised by antitoxin. 

 Roux and Buchner suggested that the antitoxin in some 

 way renders the cells and tissues insusceptible to the 



