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has been used. In such cases, the subculture must be restarted from liquid
culture perhaps also changing the anaerobic incubation.
Solid and liquid cultures are first incubated for three to five days.
The liquid media show a slightly diffuse turbidity with a whitish streaky
sediment. If the thioglycollate medium contains 0.2% agar, the microorganisms grow in the upper third of the medium.
FIG. 4 . Colonies of Campylobacter fetus subspecies intestinalis grown for 72 h
on 5% cooked sheep blood Columbia agar (magnification x 1.5).
After three to five days on solid media the colonies are smooth, low
convex, entire spherical and opalescent. Colony size varies between strains,
ranging from a diameter less than 0.5 up to 2 mm (Fig. 4). Sometimes a
slightly a-haemolytic zone appears around the colonies.
F. Immunofluorescent technique
For diagnosis of the Campylobacter carrier state in bulls examination
of preputial washing by the fluorescent antibody technique is useful in
addition to cultural methods (Philpott, 1966; Winter et al., 1967). The