Interventions for Tuberculosis Control and Elimination 2002

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Figure 34. Ability of an anti-tuberculosis drug to prevent as a companion drug
the emergence of isoniazid resistance. 463
In summary, each anti-tuberculosis medication can be assigned a grading
scale according to these three properties (table 9). 456 This explains the
reason for the high efficacy of chemotherapy regimens incorporating isoniazid,
rifampicin, and pyrazinamide.
Emergence of anti-tuberculosis drug resistance
The most convincing evidence for the mechanism of emergence of clinically
significant drug resistance is effective or functional monotherapy. This
and related mechanisms are discussed in some detail.
There are several mechanisms by which tubercle bacilli may acquire
resistance: 464
• Effective or functional monotherapy;
• Monotherapy during sterilization of special populations;
• Differences in bactericidal activity;
• Sub-inhibitory concentrations;
• Differences in post-antibiotic lag phase.
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