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New TB test quickly determines drug resistance
<TABLE cellSpacing=0 cellPadding=0 width=760><TBODY><TR><TD vAlign=top>New TB test quickly determines drug resistance
Wed 11 Oct 2006 21:57:49 BST
By Gene Emery
BOSTON, Oct 11 (Reuters) - A new tuberculosis test is faster and less expensive than conventional TB tests and lets doctors know much sooner if someone with the infectious disease is resistant to standard drugs, a study showed on Wednesday.
Typically it takes months for doctors in many countries to discover that a TB strain is resistant to a drug with conventional tests -- a drawback that is partly responsible for the 5,000 TB deaths that occur worldwide every day.
But a study conducted in Lima, Peru, and published in this week's New England Journal of Medicine shows that the risk of TB can be reduced, especially varieties unaffected by drugs now used as the first line of defense against the disease.
"We wait for people to fail their treatment," David Moore of Imperial College, London, said in a telephone interview.
"So they come to the health center every day for their treatment and they're receiving the wrong drug because they've got multi-drug resistance. They carry on infecting the healthcare staff, the other patients and their household contacts until they become sick enough that we decide to do a drug sensitivity test, and that takes another two months."
The new test, call MODS for microscopic-observation drug-susceptibility, "will change the practice of TB testing in developing countries," said co-author Robert Gilman of the Johns Hopkins Bloomberg School of Public Health.
"It needs to be widely used in places where there's a high burden of TB, and particularly where there's a high burden of multidrug-resistant TB," said Moore.
The test, which only requires rudimentary laboratory equipment and widely available chemicals, usually made a diagnosis in just seven days, compared with 13 days for one conventional test and 26 days for another.
The accuracy rate was 98 percent, at least 8 percentage points above the other tests.
LOWER PRICE
Also, the MODS test could tell doctors in about seven days if the slow-growing bacterium was resistant to any of four conventional drugs, and it was less expensive.
While the two conventional tests cost $6 and $52 per sample, the new test costs about $2, plus the price of paying laboratory works to process the liquid coughed up by patients and to look for tell-tale knots of bacteria under a simple light microscope.
MODS worked "with greater sensitivity and speed, and reliably identified multidrug-resistant tuberculosis strains in less time than two other tests that have served as the gold standard in TB detection and treatment," said Moore and his colleagues.
But in a Journal editorial, Michael Iseman and Leonid Heifets of the National Jewish Medical and Research Center in Denver, said the new results are not definitive because some strains of TB may not produce the microscopic knots and some strains of another infection may produce knots as well.
Moore said those strains are either rare, or their knots can be distinguished from the ones created by TB bacteria.
Moore said he is unsure if the new test will be widely adopted around the world because it can be labor-intensive and "people like to stick things in machines and come back with the answer a few days later. That works better in the industrialized world."
http://today.reuters.co.uk/news/Cris...-R5-Alertnet-3
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Wed 11 Oct 2006 21:57:49 BST
By Gene Emery
BOSTON, Oct 11 (Reuters) - A new tuberculosis test is faster and less expensive than conventional TB tests and lets doctors know much sooner if someone with the infectious disease is resistant to standard drugs, a study showed on Wednesday.
Typically it takes months for doctors in many countries to discover that a TB strain is resistant to a drug with conventional tests -- a drawback that is partly responsible for the 5,000 TB deaths that occur worldwide every day.
But a study conducted in Lima, Peru, and published in this week's New England Journal of Medicine shows that the risk of TB can be reduced, especially varieties unaffected by drugs now used as the first line of defense against the disease.
"We wait for people to fail their treatment," David Moore of Imperial College, London, said in a telephone interview.
"So they come to the health center every day for their treatment and they're receiving the wrong drug because they've got multi-drug resistance. They carry on infecting the healthcare staff, the other patients and their household contacts until they become sick enough that we decide to do a drug sensitivity test, and that takes another two months."
The new test, call MODS for microscopic-observation drug-susceptibility, "will change the practice of TB testing in developing countries," said co-author Robert Gilman of the Johns Hopkins Bloomberg School of Public Health.
"It needs to be widely used in places where there's a high burden of TB, and particularly where there's a high burden of multidrug-resistant TB," said Moore.
The test, which only requires rudimentary laboratory equipment and widely available chemicals, usually made a diagnosis in just seven days, compared with 13 days for one conventional test and 26 days for another.
The accuracy rate was 98 percent, at least 8 percentage points above the other tests.
LOWER PRICE
Also, the MODS test could tell doctors in about seven days if the slow-growing bacterium was resistant to any of four conventional drugs, and it was less expensive.
While the two conventional tests cost $6 and $52 per sample, the new test costs about $2, plus the price of paying laboratory works to process the liquid coughed up by patients and to look for tell-tale knots of bacteria under a simple light microscope.
MODS worked "with greater sensitivity and speed, and reliably identified multidrug-resistant tuberculosis strains in less time than two other tests that have served as the gold standard in TB detection and treatment," said Moore and his colleagues.
But in a Journal editorial, Michael Iseman and Leonid Heifets of the National Jewish Medical and Research Center in Denver, said the new results are not definitive because some strains of TB may not produce the microscopic knots and some strains of another infection may produce knots as well.
Moore said those strains are either rare, or their knots can be distinguished from the ones created by TB bacteria.
Moore said he is unsure if the new test will be widely adopted around the world because it can be labor-intensive and "people like to stick things in machines and come back with the answer a few days later. That works better in the industrialized world."
http://today.reuters.co.uk/news/Cris...-R5-Alertnet-3
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