A tuberculosis strain among a dozen patients in Mumbai has been declared as "totally drug-resistant" by the doctor treating them, although India's government is not confirming the report.
Dr Zarir Udwadia at the Hinduja National Hospital in Mumbai, said compared to classifications used by the government and the World Health Organisation (WHO) to describe multi-drug resistant (MDR) and extensively drug-resistant (XDR) TB - the patients diagnosed at his hospital were different.
"It is an untreatable form of TB in the sense that there are no available first- and second-line drugs for it in the world," he said.
"XDR is easier to treat ... there are three to four second-line drugs still available which you can treat these patients with, but (for) our patients there is none."
He said the cases highlighted the need for India to pay more attention to treating patients with severe forms of TB, which the WHO said numbered around 110 000 in 2006, a figure Dr Udwadia said was a "considerable underestimate."
But India's government said the laboratory at Hinduja hospital was not accredited for some of the tests that Dr Udwadia's team carried out and questioned the term "totally drug-resistant TB".
"The term ... is neither recognised by the WHO nor by the Revised National Tuberculosis Control Programme," it said in a statement. Such cases can be managed by national XDR-TB treatment guidelines, according to the WHO.
Dr Udwadia and colleagues found all first- and second-line TB drugs powerless against TB bacteria cultured from the patients. They also performed genetic tests on the samples.
"We confirmed that whether we used traditional culture or genetic (tests), we came up with the same resistance pattern. These patients were already exposed to these drugs and ... they did not work in them," Dr Udwadia said.
Dr Udwadia and colleagues reported their first four patients with this form of TB in Clinical Infectious Diseases, in a letter online 21 December 2011.
According to medical literature, cases of such untreatable TB were first reported in 2007 in Europe. In 2009, 15 patients in Iran were reported to be resistant to all anti-TB drugs.
(Reuters Health, Tan Ee Lyn, January 2012)