Growth Characteristics of Bordetella pertussis in the Chick Tracheal Organ Culture

In the chick tracheal organ culture of Bordetella pertussis phase I organisms, marked bacterial growths were observed in the culture medium and on the tracheal fragments. However, serum‐free fresh or conditioned medium alone as well as an emulsion of tracheal tissues prepared in the conditioned medium supported little growth of the bacteria. The need for the existence of the organ fragment was inevitable. Fluorescence microscopy of the infected tracheal fragment and a time course study of bacterial growth in the medium with the organ culture suggested that the principal site of bacterial growth appeared to be on the surface of the tracheal fragments and the increase in the culture medium might be brought about mainly by the release of bacteria therefrom.