Interventions for Tuberculosis Control and Elimination 2002

• Patients with sputum smear-positive tuberculosis or severe extrapulmonary
tuberculosis never treated before for as much as one month;
• Patients with other forms of tuberculosis (sputum smear-negative and
extrapulmonary) never treated before for as much as one month;
• Patients with sputum smear-positive tuberculosis treated previously for
one month or more (return after treatment failure, return after default,
and relapse).
No specific recommendations have been made on how to deal with patients
with continued bacteriologically active disease following a full re-treatment
course (chronic excretors).
A primary objective of any tuberculosis control program must be to
limit to the largest possible extent the emergence of organisms resistant to
the available medications. This is a guiding principle for any chemotherapy,
but it is particularly crucial in tuberculosis control, because the armamentarium
of drugs is limited and the prospects in the near future for new,
affordable drugs with an efficacy comparable to that of isoniazid, rifampicin
or pyrazinamide are slim for most low-income countries.
Choice of first-line regimen
First-line regimens of six to eight months duration are the most efficacious
available. All are based on a four-drug initial intensive phase. Whether
a four-month (with rifampicin) or a six-month continuation phase (without
rifampicin) is selected depends on the availability of resources for drugs
and personnel, and considerations about the fall-back (re-treatment) regimen,
particularly in the case of treatment failure. Twelve-month regimens
(without rifampicin) have been widely used for bacteriologically unconfirmed
disease, but their efficacy in HIV-infected patients appears to be
inferior to the shorter, but more intensive alternatives.
The continuation phase in the eight-month regimen consists of six
months of isoniazid plus thioacetazone. A frequently chosen alternative to
thioacetazone is ethambutol. This change potentially weakens the re-treatment
regimen (functional rifampicin monotherapy in the continuation
phase). This increases the risk of development of multidrug resistance.
The IUATLD therefore recommends the addition of pyrazinamide throughout
the re-treatment regimen 8 when ethambutol has been used in the continuation
phase of initial treatment.
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