A novel method for evaluating the antimicrobial activity of tuberculosis treatment regimens

Stephen H. Gillespie*, B. M. Charalambous

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


OBJECTIVE: To evaluate the clinical response to anti-tuberculosis chemotherapy rapidly. METHOD: Sputum viable counts from a previously published clinical trial comparing a standard regimen and one containing isoniazid, rifampicin and ciprofloxacin were re-evaluated using an exponential decay model. The results were fitted to a one or two phase exponential decline. The decline in viable counts followed a curve described by a single-phase exponential decay model. From these data the time taken to reduce the viable count by 50% (vt50) was calculated to estimate the bactericidal effect of the regimens. RESULTS AND CONCLUSION: This method shows promise as a means for early identification of patients who are responding poorly as a result of resistance or poor immune response and for comparing anti-tuberculosis regimens in clinical trials. The failure to show a two-phase exponential decay curve suggested that either the sputum does not contain bacteria upon which only drugs with a sterilising activity act or that they are not present in sufficient numbers to have a significant impact on the total viable count. Further studies are required to understand the physiological state of organisms being sampled in sputum.

Original languageEnglish
Pages (from-to)684-689
Number of pages6
JournalInternational Journal of Tuberculosis and Lung Disease
Issue number7
Publication statusPublished - 1 Jul 2003


  • Clinical trials
  • Drug effects
  • Mathematical model


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