Direct microscopic counting methods are based on the principle of microscopic examination of the microorganisms in the analyzed sample. There are many counting techniques developed for this purpose and there are equipment suitable for these techniques. The most commonly used direct microscopic counting methods use special microscope lenses such as Howard slides or Thoma slides or normal slides or membrane filters with a specific preparation. Direct microscopic counting methods have the serious disadvantage of counting all living and non-living microorganisms, but they also have many advantages. For example, it is easy and inexpensive to make and also results in a very short time.

The microscope factor in the application of these methods is the number of field of view in an area of ​​1 cm2. After determining the field of view of the microscope, the microscope factor is calculated. In general, the Breed Method is used for bacterial counting. The basis of this method is that a certain volume of analysis sample is spread over a certain area and the census is performed in this area. The standard measurements are volume 0,01 ml and area 1 cm2.

Rather, the microscopic counts of bacteria and yeasts in liquid test samples are performed by the Breed method. For example, the total number of bacteria in raw milk and some dairy products is determined by this method. In this method, living and non-living bacteria are counted together.

The advantages of direct microscopic counting method are that it can be obtained in a very short time, it is easy, it is low cost and cell morphology of microorganisms can be determined while counting. The disadvantages of this method are that the eyes are fatigued, the viable and non-viable cells are not differentiated, the particles in the sample are mixed with the cells and the obtained counting results are always higher than other counting results.

Direct microscopic counting studies are carried out in advanced laboratories within the framework of microbiological analyzes. During these studies, standards and analysis methods issued by domestic and foreign organizations are followed.