The central government plans to introduce a new molecular test — Whole Genome Sequencing (WGS) — for a select group of drug resistant Tuberculosis (DRT) patients at two national TB research centres by the end of this year. DRT bacteria are resistant to at least isoniazid and rifampicin, two of the most effective anti-TB drugs.
“WGS will be introduced to understand the drug resistance patterns of select patients at National Institute for Research in Tuberculosis, Chennai and National Tuberculosis Institute, Bangalore,” said Dr Sunil Khaparde, deputy director general, Central Tuberculosis Division. “We plan to expand the test to more centres in the future,” he added.
WGS refers to complete DNA sequencing of TB causing bacteria. The major advantage of WGS over the presently used culture Drug Susceptibility Testing (DST) is that it gives results of the patient’s drug resistance patterns in an hour, said Dr Camilla Rodrigues, microbiology consultant, PD Hinduja Hospital. On an average, it takes around 15 days to get culture DST results.
“It is of paramount importance to India to establish ‘fast’ DST. If only we could take the patient’s TB bacterium’s WGS and directly apply it to patient’s sample. I am waiting for that day. Most western countries have adopted WGS,” she said.
Dr Rodrigues, along with Foundation of Medical Research, has participated in a huge global study called ‘Cryptic’, which aims at conducting WGS for one lakh patients from eight counties. Of these, samples of 6,000 patients will be from PD Hinduja, Mahim. The project is supported by the Gates/Welcome Trust and will go on for three years. The results of the study will help ‘personalise’ the course of treatment for TB patients in the future, which is the need of the hour in India, Dr Rodrigues said. “The concentration of a patient’s medicine can be modulated based on data WGS data available.”