Abstract
PurposeRecurrent tuberculosis (TB) is defined by more than one TB episode per patient and is caused by re-infection with a new Mycobacterium tuberculosis (Mtb) strain or relapse with the previous strain. Recurrence of TB is one important obstacle for End TB strategy in the world and elucidating the triggers of recurrence is important for the current TB control strategy in China. This study aimed to analyze the sources of recurrent TB by the molecular genotyping method.MethodA population-based surveillance was undertaking on all culture-positive TB cases in Jiangsu province, China from 2013 to 2019. Phenotypic drug susceptibility test (DST) by proportion method and mycobacterial interspersed repetitive units-variable number of tandem repeat (MIRU-VNTR) were adopted for drug resistance and genotype detection.ResultsA total of 1451 culture-positive TB patients were collected and 30 (2.06%, 30/1451) TB cases had recurrent TB episodes. Except 7 isolates were failed during subculture, 23 paired isolates were assessed. After genotyping by MIRU-VNTR, 12 (52.17%, 12/23) paired recurrence TB were demonstrated as relapse and 11 (47.83%,11/23) paired cases were identified as re-infection. The average interval time for recurrence was 24.04 (95%CI: 19.37-28.71) months, and there was no significant difference between relapse and re-infection. For the relapsed cases, two paired isolates exhibited drug resistance shifting, while four paired isolates revealed inconsistent drug resistance among the re-infection group including two multidrug-resistant tuberculosis (MDR-TB) at the second episode.ConclusionRelapse and re-infection contributed equally to the current situation of recurrence TB in Jiangsu, China. Besides, more efficient treatment assessment, specific and vigorous interventions are urgently needed for MDR-TB patients, considering obvious performance among re-infection cases.
Highlights
Tuberculosis (TB) is an old communicable disease and the leading cause of death from a single infectious agent
A total of 1451 culture-positive TB patients were collected, including new cases and previously treated cases (WHO, 2009). Those TB patients were followed up by the National Health Management and Information System (HMIS), and we found that 30 patients presented the second episode of TB
Except 7 isolates failed in the subculture, 23 pairs of isolates were undergoing the MIRU-VNTR method to distinguish the genotypes (Figure 1)
Summary
Tuberculosis (TB) is an old communicable disease and the leading cause of death from a single infectious agent It was estimated 10.0 million people fell ill with TB in 2018, and only 7.0 million TB patients were notified and reported to WHO as new or relapse cases. There are many challenges faced by clinical and national TB control programs to achieve the targets even with improvements in TB diagnosis, treatment and prevention. One such obstacle is the recurrence of TB which varied by country and region according to previous studies (Hozbor et al, 2017; Wingfield et al, 2019). A combined analysis of the mathematical model revealed that further reducing new TB cases only has a modest effect on disease burden, but interventions that restrain reactivation have a greater improvement on disease burden in China (Houben et al, 2016)
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