Background: Recurrent tuberculosis (TB) is a major health problem in countries with a high TB burden. It is very necessary to elucidate the situation of recurrent TB in Beijing, capital of China.
Objective: To determine the proportion of recurrent tuberculosis (TB) cases and to identify relapsed or reinfected cases, as well as risk factors associated with recurrence in Beijing.
Methods: We conducted a retrospective study that included all TB cases in Beijing that were successfully treated from 2013 to 2015. Recurrence due to relapse or reinfection was determined using the variable number of tandem repeats (VNTR) method. Risk factors associated with recurrence were analysed.
Results: Tuberculosis recurred in 275 of the 4043 successfully treated TB patients, giving a recurrence rate of 6.8% (275/4043). 190 of the 275 cases were culture positive in both instances, and genotyping results for both episodes were available for 58 of these patients. The cultured isolates from 40 of the 58 recurrent cases (69%) had identical genotypic patterns in both episodes, indicating a relapse. 31% (18/58) had different genotypes, indicating reinfection by a new strain and suggested recent transmission. Those people in the 30-59 age group (p < .001), and those retreated for pulmonary TB (p < .001) were more likely to have TB recurrence.
Conclusion: Our results indicate that relapse was more common than reinfection in recurrent TB cases in Beijing from 2013 to 2015. Age and retreatment were found to be risk factors for TB recurrence.
Keywords: Tuberculosis; genotyping; recurrence; reinfection; relapse.