CHENNAI: The most feared form of drug-resistant tuberculosis has arrived in Chennai. Doctors at the National Institute for Research in Tuberculosis (NIRT) in Chennai report that they have since July treated a few TB patients who did not respond to any of the existing antibiotics for the disease. Some of the patients have died.
Researchers say they cannot as yet provide specific number of cases or the percentage of TB patients with the deadly strain of the disease, advanced extensively drug resistant tuberculosis (XDR-TB ). They say that they are still screening patients and analysing the results, but the institute confirmed instances of the strain.
"We have seen more than a dozen cases in Tamil Nadu since July. It makes TB treatment extremely difficult," said NIRT director Soumya Swaminathan.
Tuberculosis, caused by the organism Mycobacterium tuberculosis, can be fatal but is curable with a cocktail of antibiotics. But new strains of the organism with multi-drug resistance, which have surfaced in many places across the globe, have left physicians dreading the possibility that a TB 'superbug' could prove completely resistant to all drugs currently available.
When patients are resistant to the first line of treatment, they are labelled multidrug resistant (MDR-TB ). Such people are given the second line drugs that are more expensive and have greater side-effects . Patients who become resistant to second line of drugs fall into the extensively drug resistant (XDR-TB ) category.
While India has data on MDR-TB and XDR-TB , there has been no agreement on the new drug resistant strain. A group of Mumbai doctors who first found the strain in January 2012 call it totally drug resistant (TDR) tuberculosis, but WHO prefers to identify it as an advanced stage of extreme drug resistance (XDR+).
Scientists unanimously agree that the strain is as deadly as a superbug. Since July , NIRT has been screening patients in three districts of northern Tamil Nadu — Chennai, Tiruvallur and Kancheepuram — for the totally drug resistant strain.
Patients who failed the first line of treatment , those who dropped out of the programme , HIV-infected people and those who had a relapse of the bacterial infection were tested for drug resistance. The results, they said, were as expected.
The Centre will soon begin a nationwide survey to determine the incidence of the most complicated strain of tuberculosis, advanced extensively drug resistant tuberculosis(XDR-TB). The National Institute of Tuberculosis in Bangalore is drawing up a protocol for the survey which will be conducted by three government-run institutes in the country.
When the first instances of the strain, which is resistant to all known antibiotics, being detected in India were reported in Mumbai in January, the government went into denial mode. After doctors across the country said they had treated TB patients who did not respond to drugs, the government confirmed that the drug-resistant strain had arrived in India.
"We cannot say it is totally drug resistant," said Dr Ashok Kumar who heads the revised national TB control programme in India. "We only have piecemeal information now. We need comprehensive data. That's why we are planning a nationwide survey."