98 MEDICAL BACTERIOLOGY 



If concentration and repeated microscopic, examination of sputum fail to 

 reveal bacilli in a suspected case, a recently obtained sample of sputum should 

 be emulsified with sterile water and injected subcutaneeusly or into the peri- 

 toneal cavity of a guinea-pig. If tuberculosis is caused by such an injection 

 it becomes apparent in 4 to 6 weeks. After such time has elapsed the animal 

 is opened and examined for tubercular lesions. 



Examination of Spinal Fluid. Obtain from 10 to 20 cc. of spinal fluid in 

 a sterile test-tube. If the fluid is clear and has the gross appearance of normal 

 fluid, avoid agitation, place in ice box over night and inspect. The formation 

 of a delicate cobweb-like coagulum suspended in the fluid is indicative of 

 tuberculous meningitis.* This phenomenon occurs only when the fluid is pro- 

 tected from agitation i.e., transported but a short distance from the patient 

 to an ice box, and that without shaking. The tube must not be disturbed while 

 in the box, and be removed with care. 



Spinal fluid may also be examined for tubercle bacilli by centrifugalizing 

 10 cc. or more of it and making smears of the sediment on slides, staining for 

 tubercle bacilli and examining. 



Examination of Urine. A sterile bottle containing a crystal of thymol is 

 used to collect the urine. 



The external genitalia should be washed to remove smega and other bacilli 

 before obtaining the urine, whether it is obtained by catheter or micturition. 



Repeated examination may be necessary before tubercle bacilli are dis- 

 covered. 



Morning urine or the output of an entire day may be taken for examination. 



It may be centrifugalized in sterile tubes and the entire sediment collected 



and washed with sterile water once or twice and then spread on slides, dried, 



stained and examined, or the sample may be treated with antiformin as follows: 



Place the urine in a conical glass and add antiformin, a few drops at a time 



until a light precipitate begins to fall. Cover the vessel and put in a warm 



place or leave at room temperature over night. Syphon off the supernatant 



fluid and collect the sediment in sterile centrifuge tubes, wash two or three times 



with sterile water, spread on slides, dry, stain and examine. 



If a sample of 6 ounces or less of urine is to be examined it is best to sediment 

 and wash with water and not use antiformin. Antiformin is of most value 

 when the sediment from a large quantity is to be examined. 



When microscopic examinations fail to disclose tubercle bacilli and guinea- 

 pig inoculations are desirable, the sediment from 10 to 30 cc. of urine should be 

 mixed with water and several cubic centimeters injected into the peritoneal 

 cavity. 



Examination of Blood. Under strict aseptic precautions obtain from 10 

 to 50 cc. of blood from a vein with syringe and needle, add a 50 per cent, anti- 

 formin solution, a little at a time and keep in incubator until the blood is entirely 



* Very rarely diseases of the spinal cord or meninges, other than to tuberculosis show this 

 coagulum. 



