Interventions for Tuberculosis Control and Elimination 2002

Influence of isoniazid resistance on the choice
of a regimen
Isoniazid is a key drug in the treatment of tuberculosis and its inclusion in
every first-line regimen is the standard of care. Pre-existing initial resistance
to isoniazid might be conducive to the development of additional
resistance, particularly if treatment organization is poor, as the data from
the WHO/IUATLD global surveillance project on drug resistance seem to
suggest (figure 51). 600
Patients with initial isoniazid resistance who are given a four-drug
intensive phase for two months, followed by isoniazid and thioacetazone
in the continuation phase, fail more frequently than patients with fully susceptible
organisms. 519,601 Such patients can be re-treated effectively with
a regimen containing rifampicin plus ethambutol throughout, supplemented
by pyrazinamide during the first three months, and additionally by streptomycin
during the first two months. 8,13,602-604
It is not very well known how effective such a re-treatment regimen
is if there is additional ethambutol resistance. The extent to which such
functional rifampicin monotherapy in the continuation phase of the re-treat-
Any rifampicin-resistance (%)
16
14
12
10
8
6
4
2
0
Weighted regression
0 2 4 6 8
Isoniazid mono-resistance (%)
Figure 51. Correlation between isoniazid mono-resistance and any rifampicin resistance
among never treated patients. Ecological analysis from the Global Project
on Surveillance of Anti-tuberculosis Drug Resistance. 600
77