Background. Sputum smear-positive pulmonary tuberculosis patients expel infectious viable bacilli for a period following the commencement of treatment.
Objective. To determine the time to sputum smear conversion and study the factors influencing it.
Design. A prospective study was undertaken at our hospital in Rabat over a six-month period on a cohort of 119 sputum smear positive patients. Patients were followed up fortnightly. At each followup, specimens were collected and processed for microscopy using standard protocol.
Results. 96.6% of our patients completed the study (4 deaths). Sputum conversion rate was 42% after two weeks, 73% after one month, and 95% after two months. Univariate and stepwise regression analysis showed that patients who had high smear grading, miliary, and bilateral radiologic lesions were more likely to undergo delayed sputum conversion (P<0.05). Other factors were thought to influence sputum conversion but were not statistically proven in our study.
Conclusion. Since viable bacilli continue to be expelled for up to two months, infection control measures should be maintained for such a time. Patients with high smear grading, miliary, and bilateral radiologic lesions need to be monitored more closely.
Contribution of the QuantiFERON-TB Gold-in Tube test in the diagnosis of latent tuberculosis in children living with smear-positive pulmonary tuberculosis patients