CHAPTER X 



BACTERIOLOGICAL EXAMINATIONS 



THE general principles to be observed in obtaining material for 

 bacterial examination are (1) extreme care that the material is 

 not contaminated with organisms from other sources ; (2) that 

 the bacteria in the specimen are not injured by a disinfectant, 

 heat, etc. ; (3) that the material is examined with the least possible 

 delay. 



Whenever possible it is advisable to make films or inoculate 

 media directly from the patient's body. If this cannot be done 

 the material should be placed in a sterile container and sent as 

 quickly as possible to the laboratory. On no account should a 

 disinfectant be added. If a short delay is unavoidable the speci- 

 men should be kept in the refrigerator in order that development 

 of the organisms may be arrested and the stronger species may 

 not thrive at the expense of the weaker. The immediate exami- 

 nation of material containing a great number and variety of organ- 

 isms cannot be over-emphasized. If, for example, a specimen of 

 feces is to be examined for typhoid bacilli a delay of twenty-four 

 hours may result in their entire disappearance if they were present 

 in small numbers. 



Material from abscesses, open wounds, and mucous membranes 

 can best be obtained by means of a sterile swab ; fluid exudates 

 may be taken with a sterile syringe or capillary pipette. To make 

 the latter, a piece of glass tubing about ten inches long is heated 

 in the center in a Bunsen flame until it begins to soften, then with- 

 drawn and quickly stretched until the center has the required 

 diameter. The tube is cut with a file so as to obtain two tubes the 

 needed length. A little plug of cotton is placed within the large 

 ends and the pipettes are sterilized in a plugged test tube. 



105 



