CHAPTER IV 



COLLECTION OF MATERIAL FOR BACTERIOLOGICAL 



STUDY 



Bacteria under natural conditions are usually associated as 

 mixtures of several species living together. Only under rather 

 exceptional circumstances will a single kind of bacteria be found 

 growing alone. This does occur in disease, however, where the 

 living host may be able to keep out all but the one kind of microbe. 

 But even diseased tissues or exudates originally harboring only 

 one kind of bacteria may quickly acquire others in abundance 

 after removal from the living body. It is well therefore to 

 regard any material presented for bacteriological examination 

 as potentially, and in all probability actually, harboring several 

 kinds or species of bacteria. The direct planting of such material 

 on a culture medium will, therefore,, in most instances give rise 

 to a mixed culture, in which those forms least prominent in the 

 original material may easily appear as most important. If the 

 material be allowed to stand, especially if it be a favorable medium 

 for bacterial growth, the relationships present may become 

 seriously confused. It should, therefore, be examined as fresh 

 as possible. Whein immediate examination is impossible the 

 material should be kept on ice. 



Samples of water, milk or other fluid should be collected in 

 sterilized tubes or bottles. Samples of solid food should be 

 seared or charred all over the surface and divided with a sterilized 

 knife. A small piece of the interior is then removed to a sterilized 

 glass dish and covered. 



Material removed from the human or from the animal body during 

 life or at autopsy may be bacteria-free, or it may contain one or 

 more species of microbes. It is important that the picture 

 be not confused by the addition of bacteria from the surface of 



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