Abstract:
In a previous paper, an overview of the use of PET/CT in
the management of tuberculosis (TB) was provided and the
potential role of nitroimidazole imaging in LTBI was
considered [1]. During latent TB, dormant bacilli putatively
reside in a hypoxic environment of caseating lung
granulomas. Exposure of Mycobacterium tuberculosis
(Mtb) to progressive hypoxia in vitro induces a dormant
state characterized by reduced replication and metabolism
analogous to that postulated for bacilli in LTBI. In vitro,
Mtb has been shown to enter microaerophilic nonreplicating
persistent (NRP) stage 1, if the dissolved oxygen
content falls below 1 %. NRP stage 1 is characterized by
thickening of the outer cell wall of Mtb and termination of
DNA synthesis. If the oxygen content further drops to
approximately 0.06 %, the bacilli enter NRP stage 2, which
is accompanied by reduced susceptibility to standard anti-
TB drugs but increased susceptibility to nitroimidazole
drugs [2]. In light of this, metronidazole, an antimicrobial
agent active against anaerobic bacteria, has been investigated
as a possible therapy for TB, particularly latent and
persistent TB. Metronidazole has recently been documented
to be a viable option for treatment of multidrugresistant
(MDR) TB [3].
