Flagella Staining as a Routine Test for Bacteria

Abstract

The unsatisfactory character of routine tests for determining bacterial motility is emphasized. Reference is also made to the semi-solid agar method of Tittsler and Sandholzer, which is ordinarily simpler than the microscopic technic and seems to result in a considerably higher percentage of positive determinations. There are numerous cultures which appear immotile under the microscope, and give somewhat indefinite results by the semi-solid agar test but which, on staining, prove to have flagella. This raises the question as to whether a routine flagella staining method can be devised simple enough to be employed in routine pure culture study in place of the conventional test for motility. For this purpose the writers found it possible to use Hofer and Wilson''s modification of the Gray flagella stain, changing it only in the length of time to allow the organism to stand in water before making the smear on a slide. The procedure as recommended calls for slides flamed almost to the breaking point and for suspensions of bacteria allowed to stand in distilled water for from 5 to 30 min. (the longer periods for slime-forming organisms). The crucial points are the amount of heat to give the slides and the method of cooling so as to avoid breakage; slow cooling is essential. The technic proposed is hardly more difficult than the Gram stain and gives more reliable and much more significant results than either the microscopic or semi-solid agar methods of determining motility.