TB, is there anything we can do?
by Harry Kim
Mycobacterium Tuberculosis was first discovered in 1882 and it is still the leading cause of death of a single infectious agent. In 2019 alone, TB accounted for 10 million diagnosed cases and 1 to 2 million deaths. So the question arises, is there anything we can do?
The complexity of TB comes from the different levels of drug resistance the bacteria have. There are over 20 anti-TB drugs being used, all with varying resistance in the community. Undertreating leads to higher mortality and overtreating result in more significant side effects (often detrimental to patient’s life). So why after 140 years are we still making this mistake?
Due to the vast number of drugs, it is costly to have resistance testing facilitates for all anti-TB drugs. Often high TB burden countries are also developing countries and can only accommodate for isoniazid and rifampicin testing. So how do test more accurately?
All these problems have one answer: whole genome sequencing.
High throughput can be very expensive. However, in areas where TB is the number one cause of death, it can become an investment to improve the lives of the whole community as correct treatment can decrease mortality rates, decrease spread and improve symptom control.
The research shows 22% of local testing was incorrect according to the WGS testing, with half of these cases being inappropriately treated. It was also shown that 28% of mortalities had incorrect resistance testing. The odd ratio showed that patients are 4 times as likely to die when undertreated instead of receiving appropriate treatment.
The undertreatment of TB due to incorrect resistance testing results seems to be main culprit in this complex disease but whole genome sequencing is the answer to save millions.
Zürcher K, Reichmuth ML, Balif M, Louiseu C, Borrell S, Reinhard M, et al. Moratlity from drug-resistant tuberculosis in high-burden countries comparing routine drug susceptibility testing with whole-genome sequencing: a multicentre cohort study. Lancet. 2021 July;2:320-9.