04:17pm Saturday 11 July 2020

Scientists use DNA sequencing to trace the spread of drug-resistant TB

Genetic analysis of the TB bacteria revealed how a 44-year-old man who died of the disease in 2012 caught the drug-resistant infection from a healthcare worker who had worked in South Africa, when both were admitted on the same medical ward four years earlier.
TB is spread by inhaling tiny airborne droplets from an infected person. The bacteria can survive in the lungs for long periods without causing symptoms – known as latent infection.
Most infections can be treated with antibiotics, but some forms of TB are resistant to drugs. Multidrug-resistant (MDR) TB, which is resistant to at least two of the main treatments, has become more common in the UK, increasing from 28 cases per year in 2000 to 81 in 2012.
“Multi-drug resistant TB is a real problem in the UK,” said Dr Graham Cooke, lead author of the study, from the Department of Medicine at Imperial College London. “It takes a lot of time, effort and resources to treat, and treatment is less successful.”
In 2010, the Health Protection Agency (now Public Health England) began performing genetic tests on samples of TB bacteria to help identify links between patients and better understand how infections are passed on.
In an article published in Emerging Infectious Diseases today, researchers report using this genetic information to trace the source of infection in a British patient who had never travelled abroad. The DNA profile of the bacteria sample was matched to that of a patient who died in 2008. The second patient had worked as a healthcare worker at Tugela Ferry Hospital in South Africa, the location of a serious outbreak of drug-resistant TB in 2005, but was healthy upon moving to the UK to work.
Admission records established that both patients were admitted on the same medical ward in a UK hospital for eight days in 2008. As is typical with TB, the infection didn’t manifest itself in the second patient until four years later, when he was admitted to hospital and ultimately succumbed to the infection.
“Genetic sequencing enabled us to establish beyond reasonable doubt that a patient who died of multidrug-resistant TB caught the infection from another patient at a hospital in the UK,” said Dr Cooke. “Genome sequencing of pathogens is becoming part of routine practice for establishing transmission patterns for TB and other infectious diseases. This sort of analysis will help to improve our understanding of how diseases spread and identify more effective ways to stop them.
“In this case, the infection was traced to a healthcare worker. At a time when Ebola is in the news this reminds us that healthcare workers are vulnerable to many infections and, if not diagnosed, have a high risk of passing them on.”
The study was supported in part by the National Institute for Health Research (NIHR) Imperial Biomedical Research Centre, the NIHR Health Protection Research Unit (HPRU) in Healthcare Associated Infection and Antimicrobial Resistance and the NIHR HPRU in Respiratory Infections, both at Imperial College London in partnership with Public Health England.
Professor Alison Holmes, Director of the NIHR HPRU in Healthcare Associated Infection and Antimicrobial Resistance at Imperial College London, said: “The work of Dr Cooke and colleagues reinforces the fact that effective infection prevention measures are critical for protecting the lives of patients and healthcare workers globally. The paper illustrates the importance of genetic profiling in identifying and pinpointing transmission and investigating outbreaks. The development of more rapid diagnostics and molecular epidemiology will be invaluable in addressing the spread of infection and drug resistance.”

For more information please contact:

Sam Wong
Research Media Officer
Imperial College London
Email: [email protected]
Tel: +44(0)20 7594 2198
Out of hours duty press officer: +44(0)7803 886 248
Notes to editors:
1. Williams OM, et al. ‘Fatal nosocomial MDR TB identified through routine genetic analysis and whole-genome sequencing’ [letter]. Emerg Infect Dis. 2015 http://dx.doi.org/10.3201/eid2106.141903

2. About Imperial College London
Imperial College London is one of the world’s leading universities. The College’s 14,000 students and 7,500 staff are expanding the frontiers of knowledge in science, medicine, engineering and business, and translating their discoveries into benefits for society.
Founded in 1907, Imperial builds on a distinguished past – having pioneered penicillin, holography and fibre optics – to shape the future. Imperial researchers work across disciplines to improve global health, tackle climate change, develop sustainable energy technology and address security challenges. This blend of academic excellence and its real-world application feeds into Imperial’s exceptional learning environment, where students participate in research to push the limits of their degrees.
Imperial nurtures a dynamic enterprise culture, where collaborations with industrial, healthcare and international partners are the norm. In 2007, Imperial College London and Imperial College Healthcare NHS Trust formed the UK’s first Academic Health Science Centre. This unique partnership aims to improve the quality of life of patients and populations by taking new discoveries and translating them into new therapies as quickly as possible.
Imperial has nine London campuses, including Imperial West: a new 25 acre research and innovation centre in White City, west London. At Imperial West, researchers, businesses and higher education partners will co-locate to create value from ideas on a global scale.

3. About the National Institute for Health Research
The National Institute for Health Research (NIHR) is funded by the Department of Health to improve the health and wealth of the nation through research. Since its establishment in April 2006, the NIHR has transformed research in the NHS. It has increased the volume of applied health research for the benefit of patients and the public, driven faster translation of basic science discoveries into tangible benefits for patients and the economy, and developed and supported the people who conduct and contribute to applied health research. The NIHR plays a key role in the Government’s strategy for economic growth, attracting investment by the life-sciences industries through its world-class infrastructure for health research. Together, the NIHR people, programmes, centres of excellence and systems represent the most integrated health research system in the world. For further information, visit the

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