TABLE V I
Microbiological differential diagnosis among C. diphtheriae and other corynebacteria with human habitat
Enzymic characters
Morphology
MetaGrowth characters
Corynebacteriitrn
Gram
chromatic
species
staining
bodies
Tinsdale
CTBA
BA
Loeffler
Broth
C. diphtheriae
Gram-positive Present
at ends,
pleomorphic,
slender curved
club-shaped
rods, Chinese
letters
C . ulcerans
C. hofmannii
Pleomorphic, Present
Gram-positive
at ends
slender
curved rods,
and cocci of
different sizes
Gram-positive, Absent
short, regular
rods, with
pointed ends
Greyish black Black
Pearl
Granular Turbid
+ - + + + -
colonies surcolonies, greyish,
white,
or clear
rounded by a different light,
friable
culture
characteristic shapes and circular
culture
with a
brown halo
sizes,
colonies
veil on
according
surface
to the
biotype
Greyish black Greyish
Dense,
Smooth, Uniformly + - + + + +
colonies surblack,
opaque,
creamy
turbid
rounded by a smooth
smooth,
yellowish with
wide brown
raised,
convex
colonies veil on
halo
regular
colonies
surface
margins,
friable
Greyish black Smooth, Smooth. Smooth, Uniformly + - - - - +
small colonies brown
creamy
creamy,
dense,
or
without halo
colonies
sometimes dense
turbid
-
yellowish
culture
colonies