DIAGNOSIS OF TUBERCULOSIS 491 
if any were present, after careful search. This one case was shown 
by many subsequent examinations to be negative for tubercle bacilli. 
Pus from "cold abscesses" rarely shows acid-fast bacilli, although 
INIuch granules may be detected occasionally. Such material should 
be injected into guinea-pigs. The microscopic examination is the 
most rapid method of diagnosing tuberculosis bacteriologically. 
(b) Cultural.— Cultures of typical bacilli may be obtained either 
directly from lesions, fluids, tissues, or exudates, or from animals 
following inoculation with suspected material. In order to obtain cul- 
tures of tubercle bacilli from material containing other organisms as 
well, it is necessary to treat the material first with antiformin^ from 
two to three hours so as to kill off the contaminating bacteria. Anti- 
formin does not as a rule kill tubercle bacilli during this time. It 
is necessary to remo^•e the antiformin by repeated washing and cen- 
trifugalization of the tubercle bacilli before the latter are inoculated 
into artificial media, preferably Dorset's egg medium and even better, 
retrofit's medium (page 470). At best the cultural procedure is a 
relatively unsatisfactory one. 
(c) Animal Inoculation.— Animal inoculation is the most delicate 
and by far the most reliable test for demonstrating the presence of 
tubercle bacilli. Guinea-pigs are the animals selected, and the method 
of inoculation depends upon the nature of the material. If the material 
is suspected to contain tubercle bacilli only, it is introduced directly 
under the skin, or, better, intraperitoneally. If other organisms are 
associated with the tubercle bacillus, the material may either be mixed 
with antiformin and shaken for two hours to kill off or weaken the 
other organisms, then washed to remove the antiformin and the sedi- 
ment injected, or the material may be introduced, contaminating 
organisms and all, subcutaneously into a guinea-pig in the following 
manner. A subcutaneous pocket is made on the flank of the guinea- 
pig and the suspected material is introduced beneath the skin and 
pushed forward. The cut is left open and whatever pus-producing 
organisms are present cause suppuration ; the pus drains away and the 
initial inflammation is recovered from before the tubercle bacilli kill 
the animal. Tubercle bacilli then may be recovered from the regional 
lymph nodes and the internal organs. When the inguinal glands are 
well enlarged the animal is chloroformed. The skin is sterilized with 
bichloride of mercury and sterile instruments are used in performing 
the autopsy. Bits of tissue from the lymph glands, spleen, or other 
organs are removed aseptically and dropped on the surface of specially- 
prepared media, preferably the Petroft' or the Dorset egg medium. A 
microscopic examination is also made in the usual manner. 
1 Paterson: Antiformin for the Detection of Tubercle Bacilli in Sputum. Studies 
from the Saranac Laboratory for the Study of Tuberculosis, 1904-1910. Sodium car- 
bonate, 600 grams; fresh chlorinated lime, 400 grams; distilled water, 4000 grams. 
Dissolve the sodium carbonate in 1000 cc. distilled water; triturate the chlorinated 
lime in 3000 cc. distilled water; filter, and mix with the sodium carbonate solution. 
Filter again. 
