Abstract: A method and a device for separating certain microorganisms from fecal matter are described. The method is effective in relatively fast detection and identification of bacterial pathogens in e.g. chicken feces, thus making it possible to diagnose certain diseases within a short period of time. The method comprises inducing the bacteria (microorganisms) containing matter through a sequence of basically non-absorbent screens with selected, gradually decreasing pore sizes. Factors important in optimizing the separation process are discussed.