"We found that isoniazid mono-resistance backgrounds have a much higher risk of acquiring further rifampicin resistance than susceptible backgrounds. Rapid molecular tests usually focus on rifampicin resistance, which means that isoniazid mono-resistance is missed. This result in amplification into multi-drug resistance. We thus recommend that rapid molecular tests also identify regions associated to isoniazid resistance conferring mutations.
"The mutations confer 'pre-resistance'. Monitoring these mutations could prevent the amplification of drug resistance in the population by targeting those bacteria more likely to become resistant," he added.
Molecular testing for TB in children with severe pneumonia
Although TB in children commonly presents with symptoms mimicking pneumonia, its diagnosis is usually considered only if they have repeated antibiotic treatment failures or if symptoms have been present for long. Thus diagnosis of TB in kids is often missed or delayed, causing high mortality in them as they cannot access treatment because they are not diagnosed, said Dr Olivier Marcy, Research Director, University of Bordeaux. He was presenting the results of the TB Speed Pneumonia study on the yield of systematic TB molecular testing performed on nasopharyngeal aspirates and stool samples in children with severe pneumonia in countries with high TB incidence. The study investigated if offering systematic molecular testing for TB in all children with pneumonia is feasible and whether it will affect mortality.
The study was done on 1169 children aged up to 5 years, with WHO-defined severe pneumonia, enrolled in 15 hospitals from 6 high TB-incidence countries-- Cambodia, Cameroon, CÃ ´te d'Ivoire, Mozambique, Uganda, and Zambia.
"Unlike adults, children below age 5 are unable to expectorate to produce sputum for molecular testing. So one has to use easier sample collection methods. We collected stool samples and nasopharyngeal aspirate samples (that involve non-invasive methods). Although taking stool samples seem rather easy in children, it takes time to collect them and it is not as easy as the other option. We could collect nasopharyngeal aspirate samples in 97% children and stool samples in 81% children. Molecular testing of stool samples and nasopharyngeal aspirates was done using Gene Xpert Ultra. 8.0% of the children with severe pneumonia were diagnosed with TB in the intervention arm," informed Marcy.
"These are important findings. Although we have more and more data that TB is frequent in children with pneumonia, the guidelines and clinical practices are not taking this information into consideration. So we need to have better tools to detect TB in this group. Getting nasopharyngeal aspirates from them is not difficult. So it is important to convince doctors around the world that they can use this technique to diagnose TB in children," he emphasized.
Artificial Intelligence-based automatic detection system to improve diagnostic accuracy for active TB
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