including alcohols, are not effective with sputum or environmental
samples [8]. It is recommended that the efficiency of the selected
disinfectant be tested prior to routine use in the laboratory.
Laboratory staff working with mycobacterial pathogens or in
shared laboratory space can be tested annually or semiannually to
determine if any exposure has occurred. This testing can be paired
with pre-access tests to determine if exposure was from the
laboratory [8].
1.12 Biosafety
Concerns
with Nontuberculous
Mycobacteria (NTM)/
M. leprae
Beyond the M. tuberculosis complex, other facultative pathogenic
species of mycobacteria are common in the environment. Some of
these are of concern to immunocompromised people, particularly
those infected with HIV and a low CD4 cell count. These are
considered opportunistic but not communicable and may be
isolated from clinical samples but not necessarily associated with
disease. Laboratory acquired infections from NTM have not been
reported [8]. Some included species are M. avium, M. kansasii,
M. intracellulare, M. scrofulaceum, and M. ulcerans. Handling any
of the NTM in the laboratory setting should be done in a BSL-2
environment. Because M. leprae must be grown in vivo, all work
must be performed in an ABSL-2 facility by staff trained to handle
armadillos and nude mice.
1.13 Growth
of M. leprae
M. leprae can be grown in vivo using armadillos or athymic nude
mice. All work conducted with animals requires prior protocol
approval by the Institutional Animal Care and Use Committee
(IACUC), or similar institutional governance body for the ethical
management of animals in biomedical research.
Athymic nude mice are used to obtain highly viable populations
of M. leprae for research use. Typically, a suspension (30 μL) containing 1 Â 10
7 live M. leprae is inoculated in each hind footpad.
After 5–7 months, more than 5 Â 10
9 viable bacilli can be harvested
from the footpads (see Fig. 4). Athymic nude mice need to be
maintained in a specific pathogen-free ABSL-2 facility with ad
libitum food and water.
The nine-banded armadillos (Dasypus novemcinctus) (see Fig. 5)
are natural hosts of M. leprae, showing high infection rates (over
20%) in free ranging armadillos in the Southeast United States.
Their long life span (12 years), cool body temperature, and large
body size define them as excellent hosts for in vivo propagation of
M. leprae. Although armadillos have been shown to be susceptible
to experimental infection by a variety of routes, intravenous inoculation is the route of choice since it will result in higher bacterial
yield in a shorter incubation period [32, 33]. Once the armadillo
has been infected with M. leprae, the infection disseminates into the
liver and spleen and can be harvested from the tissues at 10
12
bacteria per animal [34–36].
12
Elizabeth Wallace et al.
samples [8]. It is recommended that the efficiency of the selected
disinfectant be tested prior to routine use in the laboratory.
Laboratory staff working with mycobacterial pathogens or in
shared laboratory space can be tested annually or semiannually to
determine if any exposure has occurred. This testing can be paired
with pre-access tests to determine if exposure was from the
laboratory [8].
1.12 Biosafety
Concerns
with Nontuberculous
Mycobacteria (NTM)/
M. leprae
Beyond the M. tuberculosis complex, other facultative pathogenic
species of mycobacteria are common in the environment. Some of
these are of concern to immunocompromised people, particularly
those infected with HIV and a low CD4 cell count. These are
considered opportunistic but not communicable and may be
isolated from clinical samples but not necessarily associated with
disease. Laboratory acquired infections from NTM have not been
reported [8]. Some included species are M. avium, M. kansasii,
M. intracellulare, M. scrofulaceum, and M. ulcerans. Handling any
of the NTM in the laboratory setting should be done in a BSL-2
environment. Because M. leprae must be grown in vivo, all work
must be performed in an ABSL-2 facility by staff trained to handle
armadillos and nude mice.
1.13 Growth
of M. leprae
M. leprae can be grown in vivo using armadillos or athymic nude
mice. All work conducted with animals requires prior protocol
approval by the Institutional Animal Care and Use Committee
(IACUC), or similar institutional governance body for the ethical
management of animals in biomedical research.
Athymic nude mice are used to obtain highly viable populations
of M. leprae for research use. Typically, a suspension (30 μL) containing 1 Â 10
7 live M. leprae is inoculated in each hind footpad.
After 5–7 months, more than 5 Â 10
9 viable bacilli can be harvested
from the footpads (see Fig. 4). Athymic nude mice need to be
maintained in a specific pathogen-free ABSL-2 facility with ad
libitum food and water.
The nine-banded armadillos (Dasypus novemcinctus) (see Fig. 5)
are natural hosts of M. leprae, showing high infection rates (over
20%) in free ranging armadillos in the Southeast United States.
Their long life span (12 years), cool body temperature, and large
body size define them as excellent hosts for in vivo propagation of
M. leprae. Although armadillos have been shown to be susceptible
to experimental infection by a variety of routes, intravenous inoculation is the route of choice since it will result in higher bacterial
yield in a shorter incubation period [32, 33]. Once the armadillo
has been infected with M. leprae, the infection disseminates into the
liver and spleen and can be harvested from the tissues at 10
12
bacteria per animal [34–36].
12
Elizabeth Wallace et al.