toman's tuberculosis case detection, treatment and monitoring

25. What are the current recommendations
for standard regimens?
A. Harries 1
The aims of treatment regimens are to: cure the patient, prevent death from active
disease or its late effects, prevent the emergence and spread of drug-resistant organisms,
minimize relapse, and protect the community from continued transmission of
infection.
All treatment regimens have two phases – an initial intensive phase and a continuation
phase (1, 2).
Initial intensive phase
The initial intensive phase of treatment is designed to kill actively growing and semidormant
bacilli. This means a shorter duration of infectiousness, usually with rapid
smear conversion (80–90%) after 2–3 months of treatment. The initial phase of
rifampicin-containing regimens should always be directly observed in order to ensure
adherence. That phase usually involves between three and five drugs. If initial
resistance rates are high, use of a three-drug regimen carries the risk of selecting
drug-resistant mutants, especially in patients with high bacillary loads, i.e. with smearpositive
pulmonary tuberculosis. Use of a four-drug regimen reduces the risk both of
drug resistance developing and of failures and relapses. If a patient defaults on treatment
after the initial intensive phase, relapse is less likely.
Continuation phase
The continuation phase eliminates most residual bacilli and reduces failures and
relapses. At the start of the continuation phase, numbers of bacilli are low and there
is less chance of selecting drug-resistant mutants: fewer drugs are therefore needed.
Standard tuberculosis treatment regimens
Treatment regimens recommended by WHO (1) are shown in Table 27. Standard
codes are used for tuberculosis treatment regimens: each tuberculosis drug is represented
by a standard abbreviation and each regimen has two phases. The number
1 Technical Adviser, Malawi National Tuberculosis Control Programme, Lilongwe, Malawi.
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