742 PASSIVE IMMUNIZATION SERUM THERAPY 



for the cocci producing a given infection, and hence the serum, even 

 though it is skilfully administered in large doses, will have no influence 

 upon the disease. Apparently the cocci of these resistant or "fast" 

 strains are uninjured by the antibodies in the serum. To overcome this 

 difficulty, a large number of different strains of meningococci are used 

 in immunizing horses. If, however, the serum of one laboratory is 

 found to exert no beneficial effect, the physician should use the serum 

 of another, for different laboratories probably immunize their horses 

 with cultures not in common use. It is highly desirable to secure cultures 

 of these "fast" strains. These should be sent at once to laboratories engaged 

 in the production of antimeningitic serum, for the larger the number of these 

 strains used in immunization, the more potent and valuable will the serum 

 be. 



Administration and Dosage of Antimeningitic Serum. In Acute 

 Meningitis. As a rule, serum should be injected into the spinal canal as 

 early in the disease as possible, and in such maximum amount as is com- 

 patible with safety. Intraspinal injection is absolutely necessary, for 

 the serum must be brought into contact with the infected membranes, 

 and only a trace would reach the spinal fluid if the serum were injected 

 subcutaneously or intravenously. The advantages of early administra- 

 tion are obvious, and if the symptoms are indefinite, the physician 

 should not hesitate to perform lumbar puncture and to secure fluid for 

 microscopic examination, just as he would take a throat or nose culture 

 to aid in the diagnosis of diphtheria. The maximum, or at least an 

 adequate, amount of serum should be injected, care being observed to 

 avoid undue pressure as a result of injecting too quickly or too large an 

 amount. This administration of antimeningitic serum is, therefore, an 

 important and delicate, though relatively simple, procedure. 



1. The technic of intraspinal injection has been described on p. 694. 

 Whenever possible, the serum should be injected by the gravity method, 

 and the amounts of fluid withdrawn and serum injected controlled by 

 blood-pressure readings. 



2. Lumbar puncture is performed, and the fluid collected in gradu- 

 ated tubes. In the ordinary case, fluid may be allowed to drain until 

 the blood-pressure drops about 10 mm. of mercury, or if the pressure is 

 unchanged or rises, until the fluid flows about one drop every three 

 seconds, provided there are no other evidences of collapse, such as faint- 

 ness, headache, and great restlessness. 



3. As a rule, the amount of serum injected should be slightly less 

 than the amount of fluid withdrawn. When the injection is controlled 



