Emergence of bedaquiline-resistant tuberculosis and of multidrug-resistant and extensively drug-resistant Mycobacterium tuberculosis strains with rpoB Ile491Phe mutation not detected by Xpert MTB/RIF in Mozambique: a retrospective observational study

BACKGROUND

In 2021, an estimated 4800 people developed rifampicin-resistant tuberculosis in Mozambique, 75% of which went undiagnosed. Detailed molecular data on rifampicin-resistant and multidrug-resistant (MDR) tuberculosis are not available. Here, we aimed at gaining precise data on the determinants of rifampicin-resistant and MDR tuberculosis in Mozambique.

METHODS

In this retrospective observational study, we performed whole-genome sequencing of 704 rifampicin-resistant Mycobacterium tuberculosis complex (Mtbc) strains submitted to the National Tuberculosis Reference Laboratory (NTRL) in Maputo, Mozambique, between 2015 and 2021. Phylogenetic strain classification, genomic resistance prediction, and cluster analysis were performed.

FINDINGS

Between Jan 1, 2015, and July 31, 2021, 2606 Mtbc isolates with an isoniazid or rifampicin resistance were identified in the NTRL biobank, of which, 1483 (56·9%) were from men, 1114 (42·7%) from women, and nine (0·4%) were unknown. Genome-based drug-resistant prediction classified 704 Mtbc strains as rifampicin resistant. 628 (89%) of the 704 Mtbc strains were classified MDR; of those, 146 (23%) were pre-extensively drug resistant (pre-XDR; additional fluoroquinolone resistance), and 24 (4%) extensively drug resistant (XDR; combined fluoroquinolone and bedaquiline resistance). Overall, 61 (9%) of 704 strains revealed resistance to bedaquiline: five (7%) of 76 rifampicin resistant plus bedaquiline resistant, 32 (7%) of 458 MDR plus bedaquiline resistant, and 24 (100%) of 24 XDR. Prevalence of bedaquiline resistance increased from 3% in 2016 to 14% in 2021. The cluster rate (12 single-nucleotide polymorphism threshold) was 42% for rifampicin-resistant strains, 78% for MDR strains, 94% for pre-XDR strains, and 96% for XDR Mtbc strains. 31 (4%) of 704 Mtbc strains, belonging to a diagnostic escape outbreak strain previously described in Eswatini (group_56), had an rpoB Ile491Phe mutation which is not detected by Xpert MTB/RIF (no other rpoB mutation). Of these, 23 (74%) showed additional resistance to bedaquiline, 13 (42%) had bedaquiline and fluoroquinolone resistance, and two (6%) were bedaquiline, fluoroquinolone, and delamanid resistant.

INTERPRETATION

Pre-XDR resistance is highly prevalent among MDR Mtbc strains in Mozambique and so is bedaquiline resistance; and the frequency of bedaquiline resistance quadrupled over time and was found even in Mtbc strains without fluoroquinolone resistance. Importantly, strains with Ile491Phe mutation were frequent, accounting for 31% (n=10) of MDR plus bedaquiline-resistant strains and 54% (n=13) of XDR Mtbc strains. Given the current diagnostic algorithms and treatment regimens, both the emergence of rifampicin resistance due to Ile491Phe and bedaquiline resistance might jeopardise MDR tuberculosis prevention and care unless sequencing-based technology is rolled out. The potential cross border spread of diagnostic escape strains needs further investigation.

FUNDING

The German Ministry of Health through the Seq_MDRTB-Net project, the Deutsche Forschungsgemeinschaft under Germany's Excellence Strategy Precision Medicine in Inflammation and the Research Training Group 2501 TransEvo, the Leibniz Science Campus Evolutionary Medicine of the Lung, and the German Ministry of Education and Research via the German Center for Infection Research.

Using community health workers for facility and community based TB case finding: An evaluation in central Mozambique

BACKGROUND

Mozambique has one of the highest incidence rates of both TB and HIV in the world and an estimated tuberculosis (TB) treatment coverage of only 57% in 2018. Numerous approaches are being tested to reduce existing gaps in coverage and the estimated number of missing cases.

METHODS

Thirty Community Healthcare Workers (CHWs) were tasked with increasing TB notifications by performing verbal facility-based TB screening of all people presenting for care and TB contact tracing in the community. Using routine National TB Program data, we analyzed trends in TB notifications in five intervention districts and seven control districts in Manica province the year before this project and during a one-year intervention period.

RESULTS

In the four quarters before the study, the intervention districts notified 5,219 individuals with all forms of TB, and the control districts notified 2,248 TB cases. During the study 5,982 all forms of people with TB were notified in the intervention area, an increase of 763 (14.6%) over the baseline, whereas the control districts notified 1,877 persons with TB, a decrease of -371 (-16.5%). The CHW screening activities yielded 1,502 notified and treated individuals with TB.

CONCLUSIONS

Employing CHWs to promote facility-based TB screening and household contact tracing may lead to an overall increase in TB notification.

Effects of Xpert® MTB/RIF testing and GxAlert on MDR-TB diagnosis and linkage to care in Mozambique

SETTING

The diagnosis of multidrug-resistant tuberculosis (MDR-TB) and gaps in linkage to care are the principal health challenges in Mozambique. Five GeneXpert machines and GxAlert, an eHealth platform, were installed in Sofala and Manica Provinces between 2012 and 2014.

OBJECTIVE

To test the effects of Xpert^® MTB/RIF testing and GxAlert on rifampin-resistant TB (RR-TB) diagnosis and second-line treatment initiation rates.

DESIGN

We conducted a retrospective clinical review of patients with RR-TB from March 2012 to September 2015 at these five sites. Time-series analyses were conducted to investigate the impact of Xpert on case detection and treatment. Pre- and post- analyses were conducted to investigate the impact of GxAlert.

RESULTS

A total of 32 182 Xpert tests were conducted: 4010 (12.5%) detected TB without rifampin resistance, and 306 (7.1%) had RR-TB. Of the RR-TB cases, 161 (52.6%) were started on MDR-TB treatment, 6.9% had documented culture results, and time from diagnosis to treatment initiation decreased over time. The absolute number of patients diagnosed and started on MDR-TB treatment increased by 0.26 (95%CI 0.15-0.38, P < 0.001) and 0.16 (95%CI 0.089-0.24, P < 0.001) every 6 months. GxAlert did not affect treatment initiation rates.

CONCLUSION

Implementation of Xpert testing was associated with increases in the number of patients diagnosed and started on MDR-TB treatment.