(Press-News.org) A diagnostic test for tuberculosis (TB) can accurately and quickly detect both TB and drug-resistant strains, according to a new study. The authors of a new systematic review assessing the diagnostic accuracy of the Xpert® MTB/RIF test published in The Cochrane Library say their study can provide timely advice for clinicians and policymakers in countries where TB is a major public health problem.
Millions of people develop TB every year. Around 13% of cases occur in people living with HIV and more than a quarter of these people die as a result. Drug resistance is a major public health problem that further complicates efforts to control TB. Multidrug-resistant TB is defined as resistance to rifampicin and isoniazid, which are two of the most effective and widely used anti-TB drugs. Xpert® (Cepheid Inc, California) is a diagnostic test endorsed by the World Health Organization (WHO) that simultaneously detects TB and resistance to rifampicin, as an indicator of multidrug resistance. The test takes around two hours, with minimal hands-on technical time required.
Like sputum smear microscopy, which relies on detecting TB with a microscope in a laboratory, Xpert requires a sample of sputum. However, while thousands of bacteria must be present in each millilitre of sample for TB to be detected under the microscope, Xpert can detect TB bacteria at much lower concentrations. In addition, the conventional microscopy approach does not detect drug resistance. Instead, TB has to be grown in the lab. This presents problems, especially for multidrug-resistant TB, due both to the length of time required for the cultures to grow and the specialized laboratories and highly skilled staff needed.
The researchers, from the Cochrane Infectious Diseases Group, McGill University and the Foundation for Innovative New Diagnostics (FIND), analysed data from 18 studies involving a total of 7,816 people, with most studies being carried out in low- and middle-income countries. The results show that when Xpert is used to screen 1,000 people, 150 of whom have TB, it picks up 132 of the 150 cases (88%) and falsely diagnoses 17 (2%) with TB. This is in a scenario where it is being used as a replacement for smear microscopy. In a scenario where Xpert is being used as a replacement for culture-based drug susceptibility testing, it is also able to detect the equivalent of 141 out of 150 cases (94%) of rifampicin resistance. When Xpert is used as a follow-on test, after conventional smear microscopy has already produced a negative result, it picks up 101 out of 150 cases (67%). By definition, smear-negative TB is not picked up by smear microscopy because microscopy cannot detect small numbers of bacteria. Xpert picked up 67% of this group that would have been missed by microscopy.
"This study represents the most comprehensive review on the diagnostic accuracy of Xpert to date and may help countries make decisions about scaling up its use for management of TB and drug-resistant TB," said lead researcher, Karen Steingart, of the Cochrane Infectious Diseases Group.
Karin Weyer, Coordinator, Laboratories, Diagnostics and Drug Resistance at the World Health Organization (WHO) said, "This Cochrane Review provides high quality evidence that reinforces WHO's endorsement of this test. Recent price reductions have greatly facilitated roll-out of this technology, including a new three-year initiative called the TB Xpert Project, funded by UNITAID and executed by WHO and the Stop TB Partnership. 1.4 million test cartridges and over 200 GeneXpert instruments for the rapid detection of TB and rifampicin resistance will be distributed in 21 countries with a high burden of TB."
Lucica Ditiu, Executive Secretary of the Stop TB Partnership, said, "We welcome the Cochrane Review of Xpert, an innovation that represents a major milestone in our quest to achieve the goal of zero deaths from TB – which is curable but still takes the life of three people every minute. The Stop TB Partnership is making every effort to help countries understand how best to use this new technology. Our TB REACH initiative is deploying Xpert to numerous countries through projects that seek to increase the number of TB cases detected and treated, and these projects will deliver data that can provide an evidence base for determining how Xpert should be used for the greatest impact."
###URL Upon publication: http://doi.wiley.com/10.1002/14651858.CD009593.pub2 (The full review will be available open access upon publication)
Accompanying Podcast (available from 31st January): http://www.cochrane.org/podcasts/issue-1-january-2013/xpert-mtbrif-test-detection-pulmonary-tuberculosis-and- rifampicin-resi
Tuberculosis: WHO-endorsed test offers rapid detection
2013-01-31
ELSE PRESS RELEASES FROM THIS DATE:
New research shows complexity of global warming
2013-01-31
Global warming from greenhouse gases affects rainfall patterns in the world differently than that from solar heating, according to a study by an international team of scientists in the January 31 issue of Nature. Using computer model simulations, the scientists, led by Jian Liu (Chinese Academy of Sciences) and Bin Wang (International Pacific Research Center, University of Hawaii at Manoa), showed that global rainfall has increased less over the present-day warming period than during the Medieval Warm Period, even though temperatures are higher today than they were then. ...
Tuberculosis may lurk in bone marrow stem cells of infected patients, Stanford researchers say
2013-01-31
STANFORD, Calif. - Tuberculosis is a devastating disease that kills nearly 2 million people worldwide each year. Although antibiotics exist that can ameliorate the symptoms, the courses of therapy last for months and don't completely eradicate the disease, which frequently recurs years or decades after the initial treatment.
Now, in a classic case of bench-to-bedside research, scientists at the Stanford University School of Medicine have discovered a possible reason for the disease's resistance: The ability of the tuberculosis bacteria to infiltrate and settle down in ...
Arunachal contributes in detecting stem cells where dormant TB bacteria hide
2013-01-31
The Idu-Mishmi community and Arunachal Pradesh appeared on the world map today for its greatest contribution in studying dormant Mycobacterium in TB that has affected nearly 4 billion people in the world and causing 1.9 million deaths yearly. In India, one person is dying of TB every 3 minutes. The study details and the contribution of Idu-Mishmis of Arunachal Pradesh and RIWATCH (Research Institute of World's Ancient Traditions Cultures and Heritage) in accomplishing the study has been duly acknowledged in a research paper published in a reputed journal 'Science Translational ...
Tenofovir Gel wins out in drug absorption study, but HIV prevention trials say differently
2013-01-31
PITTSBURGH, Jan. 30, 2012 –A novel head-to-head study looking at differences in how the antiretroviral (ARV) drug tenofovir gets absorbed in the body as either an oral tablet or a vaginal gel found tenofovir gel can achieve substantially higher concentrations of active drug in vaginal tissue than the oral tablet, suggesting that tenofovir gel should be highly effective in protecting women against HIV transmitted through vaginal sex. Yet, as unequivocal as the study's results may be, they have not been borne out in HIV prevention trials to date, leading the researchers to ...
Antibiotics cut death rate for malnourished children
2013-01-31
Severely malnourished children are far more likely to recover and survive when given antibiotics along with a therapeutic peanut-based food than children who are simply treated with the therapeutic food alone, researchers at Washington University School of Medicine in St. Louis have found.
"The findings are remarkable," says Indi Trehan, MD, lead author of the research, published Jan. 31 in The New England Journal of Medicine. "Based on previous research, we didn't think there would be much benefit from antibiotics. We did not at all expect to see a drop in the death ...
Vultures foraging far and wide face a poisonous future
2013-01-31
A first ever study of the range and habits of white-backed vultures across southern Africa shows that they often shun national parks, preferring to forage further afield on private farmland.
This behaviour and their tendency to scavenge in groups, means that vultures risk encountering dead cattle that have been administered veterinary drugs that are poisonous to them, or even poisoned carcasses intended to control other carnivores such as jackals.
The research, using Global Positioning System (GPS) satellite transmitters to track the movements of adolescent vultures, ...
Exposure to antiepileptic drug in womb linked to autism risk
2013-01-31
Children whose mothers take the antiepileptic drug sodium valproate while pregnant are at significantly increased risk of autism and other neurodevelopmental disorders, suggests a small study published online in the Journal of Neurology Neurosurgery and Psychiatry.
The authors base their findings on children born to 528 pregnant women between 2000 and 2004 in the North West of England.
Just fewer than half the mums (243) had epilepsy, all but 34 of whom took antiepileptic drugs during their pregnancy. Fifty nine mums took carbamazepine; 59 took valproate; 36 took lamotrigine; ...
Bonobos predisposed to show sensitivity to others
2013-01-31
Comforting a friend or relative in distress may be a more hard-wired behavior than previously thought, according to a new study of bonobos, which are great apes known for their empathy and close relation to humans and chimpanzees. This finding provides key evolutionary insight into how critical social skills may develop in humans. The results are published in the online journal PLOS ONE.
Researchers from the Yerkes National Primate Research Center, Emory University, observed juvenile bonobos at the Lola ya Bonobo sanctuary in the Democratic Republic of Congo engaging ...
Study finds parasites and poor antenatal care are main causes of epilepsy in Africa
2013-01-31
The largest study of epilepsy in sub-Saharan Africa to date reveals that programmes to control parasitic diseases and access to better antenatal care could substantially reduce the prevalence of the disease in this region.
Epilepsy is one of the most common neurological conditions worldwide and it is well known that it is significantly more prevalent in poorer countries and rural areas. The study of over half a million people in five countries of sub-Saharan Africa is the first to reveal the true extent of the problem and the impact of different risk factors.
The ...
Risk of unwarranted pregnancies with morning after pill conscience clauses
2013-01-31
[The fox and the grapes: an Anglo-Irish perspective on conscientious objection to the supply of emergency hormonal contraception without prescription Online First doi 10.1136/medethics-2012-100975]
Conscience clauses, which allow pharmacists to opt out of providing the "morning after pill" without a prescription, risk unwanted pregnancies and undermine the principle of universal healthcare in the NHS, say pharmacists in the Journal of Medical Ethics.
These clauses should either be banned or enhanced so that pharmacists and patients know exactly where they stand, rather ...