10 Jun

Smear Preparation

Bacterial smear preparation is an integral technique in microbiology laboratories.  There are several objectives when preparing a smear.  The first is to make sure that the cells adhere to the microscope slide so that they do not get washed off during the staining and washing procedures.  It is also important to prevent the cells from shrinking.  Finally, it is very important to prepare thin smears.  If a smear is too thick one will not be able to see individual cells, their arrangement, or the details of their microstructures.  Thick smears with large clumps of cells can entrap the stain preventing it from being washed.  The first step in preparing a smear depends on  whether the organism has been growing in liquid or solid media.  Two or more loopfuls of liquid media containing the organism can be placed on the slide.  One can use an inoculating loop to disperse organisms from solid media into a drop of water on the slide.