Pigmentation Inoculate 0.1 mL from the
primary growth tube into
two L-J slants. Wrap foil
around one tube and
incubate both tubes under
general growth conditions
Date growth is evident
N/A
Scotochromogen—
pigment
development (color
other than buff/
cream) in darkness.
Photochromogen—
pigment
development in light
Nonchromogen—
no pigment
development
Growth at
25, 37,
45, and
55
C
Inoculate 0.1 mL from the
primary growth tube into a
Middlebrook 7H9 broth
tube
Check growth on a weekly
basis, and record growth
date on the date growth is
evident. Record No
Growth 1 week after initial
growth date or 21 days,
whichever is longer
N/A
Growth
No growth
TCH
Prepare a barely turbid
suspension of the test
isolate in sterile water or
saline. Dilute suspension to
10
À3
and 10
À5
with sterile
water or saline. Add 0.1 mL
of each dilution to a TCH
plate
7, 14, and 21 days
N/A
Growth
!1% of control
growth
Growth
<1% of
control growth
Iron uptake
Prepare a light suspension of
the test isolate from a pure
culture. Transfer 0.1 mL to
one L-J + 2.5% ferric
ammonium citrate tube
and one control tube of
iron citrate-free L-J
medium
Incubate in 5–10% CO
2 at
35–37
C with caps
loosened. Check weekly for
up to 4 weeks
N/A
Brown colonies
No pigment
(continued)
Culturing Mycobacteria
17