Tuberculosis relapse is more common than reinfection in Beijing, China

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. 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. 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. 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 (<i>p</i> &lt; .001), and those retreated for pulmonary TB (<i>p</i> &lt; .001) were more likely to have TB recurrence. 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.

复发性结核病（TB）是结核病高负担国家的重大公共卫生问题。阐明中国首都北京的复发性结核病流行现状具有重要意义。本研究旨在明确北京市复发性结核病病例占比，鉴别复燃性复发与新菌株再感染病例，并分析与结核病复发相关的危险因素。我们开展了一项回顾性研究，纳入2013至2015年北京市所有成功治愈的结核病病例。采用可变数目串联重复序列（variable number of tandem repeats, VNTR）基因分型法判定复燃或再感染导致的结核病复发，并对相关危险因素进行分析。在4043例成功治愈的结核病患者中，共计275例出现结核病复发，复发率为6.8%（275/4043）。275例复发患者中，190例两次病原培养均呈阳性；其中58例患者的两次发作菌株均获得了完整基因分型结果。58例复发患者中的40例（69%）两次发作的培养分离株基因型完全一致，提示为复燃性复发；剩余31%（18/58）的菌株基因型存在差异，提示为新菌株再感染，即存在近期传播风险。30~59岁年龄段人群（p<0.001）以及复治肺结核患者（p<0.001）发生结核病复发的风险更高。本研究结果显示，2013至2015年北京市复发性结核病病例中，复燃性复发较新菌株再感染更为常见；年龄与复治情况为结核病复发的危险因素。