IV. INVESTIGATION OF C . DIPHTHERIAG
119
FIG. 25. C. ulcerans.
morphic readily decolourised cocci without bacillary forms. Broth cultures
display a greater capacity to show bacillary forms.
(b) Growth, aerobic, optimum temperature 37°C.
(c) Cultural characters. On Loeffler slants-a thick, rich, creamy culture.
On CTBA large greyish black, dense colonies with regular margins and
shiny-smooth surface are produced. On blood agar plates, large, dense,
opaque yellowish-white colonies, with a smooth surface develop. The
consistency is friable and easily emulsifiable.
On Tinsdale plates, large black colonies are surrounded by an intense and
precocious brown halo which appears in about 16-24 h at 37°C. In broth,
slightly turbid cultures, with a veil or ring on the surface are produced.
These clarify the next day, forming a powderish deposit at the bottom of
the tube.
(d) Enzynzes. Enzymic activity is very intense and reactions are rapidly
produced.
Carbohydrate fermentations : acid with glucose, maltose, levulose,
119
FIG. 25. C. ulcerans.
morphic readily decolourised cocci without bacillary forms. Broth cultures
display a greater capacity to show bacillary forms.
(b) Growth, aerobic, optimum temperature 37°C.
(c) Cultural characters. On Loeffler slants-a thick, rich, creamy culture.
On CTBA large greyish black, dense colonies with regular margins and
shiny-smooth surface are produced. On blood agar plates, large, dense,
opaque yellowish-white colonies, with a smooth surface develop. The
consistency is friable and easily emulsifiable.
On Tinsdale plates, large black colonies are surrounded by an intense and
precocious brown halo which appears in about 16-24 h at 37°C. In broth,
slightly turbid cultures, with a veil or ring on the surface are produced.
These clarify the next day, forming a powderish deposit at the bottom of
the tube.
(d) Enzynzes. Enzymic activity is very intense and reactions are rapidly
produced.
Carbohydrate fermentations : acid with glucose, maltose, levulose,