Setting: Pulmonary tuberculosis (TB) patients enrolled in four provinces of Rwanda.
Objective: To determine the cause of recurrent TB.
Design: Serial Mycobacterium tuberculosis isolates obtained from patients with recurrent TB from January 2002 to September 2005 were genotyped by spoligotyping and mycobacterial interspersed repetitive unit-variable number of tandem repeat (MIRU-VNTR) typing. Drug resistance was determined by phenotypic susceptibility testing and sequencing of rpoB, katG, inhA and embB genes.
Results: Among 710 culture-positive TB patients enrolled in the study, initial drug susceptibility testing results were available for 638. Sixty-nine of these had multidrug-resistant (MDR) TB and 569 were non-MDR-TB. Among the MDR-TB patients, 22 had follow-up isolates after cure (n = 12) or chronic infection (n = 10). The DNA patterns of sequential isolates from 4 of the 12 previously cured MDR-TB patients were different, indicating re-infection. DNA patterns of isolates from the remaining 8 previously cured and 10 chronic MDR-TB patients were identical, suggesting reactivation and treatment failure, respectively. Among the non-MDR-TB patients, disease recurrence was observed in one case; this was determined to be due to reactivation after initial mixed infection.
Conclusion: These results document a high treatment failure/reactivation rate for MDR-TB and suggest that re-infection within 2 years may not be a common cause of recurrent TB in this setting.