New motility medium for nonfermenting bacilli.

Researchers compared use of a semisolid agar plate to wet mount examinations of broth cultures (16 to 18 hours) for the detection of motility of 96 reference and clinical strains of gram-negative rods. In this double blind study, 83 nonfermentative and 13 oxidase-producing, fermentative bacilli were tested by the two methods. Overall accuracy of the semisolid agar motility test was 96.8 percent compared to 89.6 percent for the broth method. Reproducibility of agar plate tests using selected reference strains was 100 percent in contrast to 90 percent for broth examinations. These findings indicate that the semisolid agar plate offers a convenient and more accurate method than wet mount examination for determining motility of unusual gram-negative bacilli.