Frequency and type of microbiological monitoring of multidrug-resistant tuberculosis treatment.

Monthly culture is usually recommended to monitor treatment of multidrug-resistant tuberculosis (MDR-TB). As mycobacterial laboratory capacity is limited in many settings, TB programs need evidence to decide whether monthly cultures are necessary compared to other approaches. We simulated three alternative monitoring strategies (culture every 2 or 3 months, and monthly smears alone) in a cohort of MDR-TB patients in Estonia, Latvia, Philippines, Russia and Peru from 2000 to 2004. This retrospective analysis illustrated that less frequent testing delays confirmation of bacteriological conversion. This would prolong intensive treatment, hospitalization and respiratory isolation, increasing cost and toxicity. After conversion, less frequent testing could delay diagnosis of possible treatment failure.

Clinical symptoms and microbiological outcomes in tuberculosis treatment trials.

During a recent Food and Drug Administration workshop on clinical trials to evaluate new TB drugs, questions were raised regarding the use of bacteriologic endpoints such as treatment failure and relapse as measures of improvement in health status and long term outcome after treatment. FDA scientists asked how patients' clinical signs and symptoms changed during therapy, noting that while such information is usually collected during clinical trials, it is not often reported. We analyzed data from an international phase 3 TB treatment trial that included systematic assessments of symptoms. The percentage of subjects with self-reported symptoms at baseline ranged from 30% for dyspnea to 81% for cough, with 51% reporting fever. During therapy, fever, sweats, and dyspnea decreased most rapidly, with near resolution by the end of therapy. Chest pain and cough resolved more slowly; 13% of subjects reported cough at six months. Symptom resolution during treatment did not differ between those who relapsed and those who did not. Among those with microbiological relapse, symptoms returned with significant increases in the proportion with fever, cough, and chest pain. At the time of relapse, cough was the most frequent symptom, occurring in 75% of subjects who relapsed but only 12% of those who did not. Our data support the continued use of bacteriologic endpoints based on sputum culture as surrogate measures of the relief of symptoms, improvement in health status and favorable long term treatment outcome in TB drug trials.

Bacteriologic monitoring of multidrug-resistant tuberculosis patients in five DOTS-Plus pilot projects.

BACKGROUND: Multidrug-resistant tuberculosis programs in DOTS-Plus pilot sites in five countries. OBJECTIVES: To calculate sputum conversion time and its relationship to treatment outcome, document the frequency of culture reversions and examine concordance of smear and culture to assess the potential consequences of monitoring by smear microscopy alone. DESIGN: Retrospective cohort analysis of 1926 patients receiving individualized, second-line therapy. RESULTS: Among 1385 sputum culture-positive cases at baseline, 1146 (83%) experienced at least one culture conversion during treatment. Conversion, however, was not sustained in all patients: 201 (15%) experienced initial culture conversion and at least one subsequent culture reversion to positive; 1064 (77%) achieved sustained culture conversion. Median time to culture conversion was 3 months. Among 206 patients whose nal conversion occurred 7-18 months after the initiation of therapy, 71% were cured or had completed treatment. CONCLUSIONS: Prolonged treatment for patients with delayed conversion may be beneficial, as 71% of late converters still achieved cure or completed treatment. This has implications for programs with de ned end points for treatment failure. The interval between rst and nal conversion among patients whose initial con- version is not sustained raises concern with respect to the ongoing debate regarding duration of treatment and the definition of cure.