TB test 'could save lives'

Some bacteria can fight off antibiotics more effectively

A way of spotting dangerous antibiotic-resistant TB bacteria has been developed by British experts.

The test - developed by the Public Health Laboratory Service - can check the genetic profile of bacteria to see if they are among those adapted to fight key drugs.

Approximately 6% of TB cases in the UK involve bacteria which have some resistance to Isoniazid, or Rifampicin, the principal antibiotics used by doctors.

The main advantage is that doctors can work out who has drug-resistant TB and give them the most effective medication

Professor Francis Drobniewski, PHLS

Elsewhere in the world, the rate is far higher, and even in the UK, cities such as London have a rising proportion of drug-resistant cases.

Normally, it takes two to four weeks after a case is reported to grow the bacteria in culture for testing.

Then it takes the PHLS another 10 to 14 days to check it for resistance.

The new method means the second half of the testing process can be completed in just one or two days.

Swift action

This means that patients can be moved to different, more effective medication more swiftly - as can people with whom they have been in contact, but who have not yet developed the disease.

And its developers are hopeful that eventually the need for the initial weeks of waiting will be removed by a test which can be carried out on the sputum of a patient.

Professor Francis Drobniewski, from the PHLS Mycobacterium Reference Unit, told BBC News Online, said: "The tests correctly identified three-quarters of Isoniazid-resistant isolates.

"The main advantage is that doctors can work out who has drug-resistant TB and give them the most effective medication.

HIV patients

"This is important, particularly in the case of patients who are immunosuppressed, such as those who are HIV-positive or who are undergoing cancer treatment."

The array test developed at the PHLS looks at small sections of a bacterium's DNA known to contain the genes, which, when mutated, confer the resistance to antibiotics.

It is no more expensive to carry out than existing tests, said Professor Drobniewski.

The results of the evaluation of the test will be revealed at the PHLS annual conference in Warwick on Tuesday.