260 BACTERIOLOGICAL EXAMINATION OF MATERIAL 
ism, and by Wright's method to distinguish the types of cellular 
elements and their relation to the microorganisms. If the fluid is 
clear, or if lymphoid cells predominate, an infection with the tubercle 
bacillus is immediately suggested. Sediment from such a fluid should 
be injected into a guinea-pig, using the method outlined for suspected 
spinal fluid. A turbid fluid usually indicates an infection with the 
streptococcus, pneumococcus, staphylococcus or pneumobacillus, if the 
material is from the pleurae or pericardium; an infection with the 
streptococcus or members of the intestinal group if the source is the 
peritoneal cavity. Rarely the gonococcus has been found. An 
examination of the Gram-stained smear will indicate the proper 
medium to use for the isolation of the organisms in pure culture. 
Pus.— A Gram stain of pus will indicate, as a rule, the proper 
medium to use for the isolation and identification of the organisms. 
Pus from "cold" abscesses frequently contains no organisms recog- 
nizable either by Gram- or acid-fast stains; experience has clearly 
demonstrated, however, that a small amount of the material injected 
subcutaneously into guinea-pigs will cause their death, frequently 
within three weeks. At autopsy, tubercles and tubercle bacilli are 
foimfl in abundance. Much and others believe that tubercle bacilli 
found in the pus from cold abscesses do not exist in their normal form, 
but appear as granules— the so-called Much granules— which are 
however, viable and virulent for guinea-pigs. In this animal the 
organisms regain their normal morphology and staining reactions. 
The possibility of hyphomycetes in the pus from old cavities in the 
lungs should be borne in mind. Actinomyces are usually visible to 
the naked eye as minute, yellowish granules which exhibit the char- 
acteristic clubs when viewed under the microscope in properly stained 
specimens. Pus from abscesses in the cervical region may contain 
spiral organisms. The occurrence of these organisms should suggest 
the possibility of a sinus connecting the abscess with the mouth. Fre- 
quently such a sinus originates at the base of a carious tooth. 
Examination of Urine.— A bacteriological examination of the 
urine is of value not only in the diagnosis of infection of the genito- 
urinary system; it may aft'ord information of the causative organisms 
in septicemia, and occasionally those concerned in the more chronic 
heart or joint lesions as well. 
The external genitalia are usually contaminated with B. smegmatis, 
which resembles the tubercle bacillus in its morphology and staining 
reactions, and with various adventitious organisms as well. Promi- 
nent among the latter is B. coli. A satisfactory sample of urine for 
bacteriological examination may be obtained from males if the glans 
and meatus are first thoroughly cleansed with soap and water. The 
greater amount of urine passed should be rejected, and the last portion 
should be collected in a sterile, wide-mouthed bottle. It is necessary 
to catheterize a female after a preliminary cleansing with soap and 
water, to obtain a satisfactory specimen for bacteriological examination, 
