CHAPTER XXX. 

 EXAMINATION OF PUS. 



Pus may be collected for examination either (i) with a platinum 

 loop, (2) with a sterile swab, (3) with a bacteriological pipette or (4) 

 with a hypodermic syringe. 



It is always well to make a smear and stain it by Gram's method at 

 the same time that cultures are made. The Gram stain gives informa- 

 tion as to the abundance of organisms in the pus and as to the probable 

 findings in the culture. Pneumococci and streptococci are differen- 

 tiated from the staphylococci in this way without the necessity of more 

 or less extended cultural methods. 



When autogenous vaccines are to be made, the isolation of the 

 exciting organism is necessary. This is best done by streaking the 

 pus, taken up with a sterile swab and emulsified in a tube of bouillon, 

 over the surface of an agar plate. Practically as convenient and provid- 

 ing a more nutritious medium is to smear the material on a loop or 

 swab over the surface of a blood-serum slant, then to inoculate a second 

 tube from the first without recharging the loop or swab, and so on until 

 three or four tubes are inoculated. Isolated colonies should be ob- 

 tained in the third or fourth tube. 



In examining blood serum slants inoculated with purulent material, 

 always examine the water of condensation for streptococci. 



A bacteriological pipette is very useful when pus is to be sent to 

 a laboratory; the tip can be sealed in a flame and the cotton plug at 

 the other end insures the noncontamination of the contents. The 

 material may be drawn up either with the mouth or with a rubber bulb. 



The hypodermic syringe is very useful in puncturing buboes, etc., 

 especially in plague. A small pledget of cotton on a toothpick dipped 

 into pure carbolic acid and touched to a spot over the bubo, which 

 after about thirty seconds is soaked with alcohol, makes a sterile 

 anaesthetic spot at which to introduce the needle of the syringe. It 



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