Aimed at upscaling diagnostic facilities to detect TB effectively in less time, Mumbai would soon have 5 more Genexpert machines making it to a total of 21 Genexpert machines under its TB control programme. Around 16 machines are currently functional and 4 are in the process of getting installed.

Government has also upscaled sensitive diagnostic modalities in 10 cities of the country as a part of its implementation research projects by using Genexpert to pick up TB and MDR TB in children.

Genexpert test is a molecular test which detects the DNA in TB bacteria. It uses a sputum sample and can give a result in less than 2 hours. It can also detect the genetic mutations associated with resistance to the drug rifampicin. New TB tests are required because of the difficulties associated with the tests that are currently used both to diagnose TB as well as to detect drug resistance.

Traditionally TB has been diagnosed by looking for evidence of TB bacteria either through the use of the chest X-ray, through sputum smear microscopy, or through the culturing of bacteria. Each of these TB tests has their disadvantages, one of the most significant for culture being the time that it takes and for sputum in terms of accuracy.

In addition to diagnosing TB, there is also a need to test for drug resistance so that the most effective TB treatment can be provided. Culture is currently the main tool for drug susceptibility testing (DST). However, not only is the length of time it takes is a problem, but it also requires trained personnel and expensive laboratory equipment.

Genexpert has gained further impetus as experts advocate the need for DST to be made available to all patients and then provide individualised treatment with the help of DST. Now there is also a thrust upon designing treatment regimens to offer optimal and shorter dosages for children suffering from TB.

Setting up of more such machines is a welcome change as a pilot project on universal DST is likely to start in Mumbai. The universal DST plan entails testing every presumptive TB patient for drug resistance as soon as he or she goes to a doctor. The universal DST is part of the World Health Organisation's strategy to 'end TB by 2035'.

Currently, a patient is first tested for simple TB that needs six to nine months of treatment. If the patient doesn't respond to this treatment within three months, he is tested further for drug resistance. If the patient is resistant to two of the normal drug regimens, he is said to suffer from multi-drug resistant (MDR) TB. If the patient is resistant to more than two drugs as well as an antibiotic injection given to MDR-TB patients, he has extensively drug-resistant (XDR) TB.

Drug-resistant TB needs over two years of treatment, with drugs costing more than Rs.2 lakh.