DNA sequencing can trace the spread of drug-resistant tuberculosis

Scientists at Imperial College London in England used DNA sequencing to trace the fatal spread of multidrug-resistant tuberculosis (TB) between patients in the UK.

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The research team performed genetic analysis of the TB bacteria using the Illumina MiSeq system, which 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.

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 the 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," says Dr. Graham Cooke of the Department of Medicine at Imperial College London, who led the study. "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."

"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," says Professor Alison Holmes, director of the NIHR HPRU in Healthcare Associated Infection and Antimicrobial Resistance at Imperial College London. "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."

Full details of the work appear in the journal Emerging Infectious Diseases; for more information, please visit http://dx.doi.org/10.3201/eid2106.141903.

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