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Our scientists recently published a scientific paper reporting the discovery of a severe, drug-resistant form of tuberculosis in Nigeria. The discovery was made using whole genome sequencing (a technique for analysing the entire genome of an organism) and bioinformatics analysis.
We share four key highlights of the publication below:
1. The Beijing lineage of Mycobacterium tuberculosis complex is in Nigeria
The Beijing lineage of Mycobacterium tuberculosis complex (MTBC), which is notorious for severe symptoms, faster progression of disease and resistance to several drugs is present in Nigeria. A bacteria lineage is a group of bacteria that have similar forms, but also have different characteristics because of changes (mutations) in portions of their genome. Mutations in the genome of MTBC (the group of bacteria that cause tuberculosis) help the bacteria to adapt to and resist different drugs administered against the disease.
2. Common antimicrobial resistance tests misdiagnosed it
Common lab techniques used to determine the level of drug resistance in the bacteria wrongly classified them as milder forms of TB. Prior to treatment of tuberculosis, reference labs generally conduct tests to determine the level of drug resistance in the bacteria that infects the patients. Drugs are prescribed based on the results of such tests. This is because the bacteria have different levels of resistance to different drugs, a phenomenon termed antimicrobial resistance (AMR). That the tests misdiagnose this means patients can be given drugs that may not successfully treat the disease. This means that patients’ conditions may not improve despite treatment.
3. First extensively drug-resistant TB diagnosed with whole genome sequencing in Nigeria
Dubbed extensively drug-resistant TB (XDR TB), the bacteria is a rare type of multi-drug resistant TB (MDR TB), which is resistant to two of the most important drugs (the first-line drugs) used to treat TB. The XDR TB bacteria have mutations (genetic changes) that help them resist all first-line anti-TB drugs, at least one second-line medication and at least one third-line drug. This was confirmed for the first time in Nigeria using whole genome sequencing.
4. Whole genome sequencing is more reliable
Whole genome sequencing (WGS) is a more reliable way of detecting antimicrobial resistance in TB bacteria. The continuous reduction in the cost of next generation sequencing provides an opportunity to strengthen the diagnosis of TB in hospitals and reference labs within low-to-middle income countries and in regions with high TB burden. This will greatly improve the detection accuracy of antimicrobial resistance in infections.
Conclusion
As Nigeria and other countries that carry heavy TB burdens continue to combat this disease, especially in the face of the Covid-19 pandemic, appropriate diagnostics is essential. Strengthening existing laboratory networks to perform WGS is a step in the right direction
Written by: Fikayo Oyewale
