Gene analysis can trace spread of drug-resistant TB

Researchers in Britain have used genetic analysis of the tuberculosis (TB) bacteria to trace the fatal spread of multidrug- resistant TB between patients.

DNA sequencing of the bacteria revealed how a 44-year-old man who died of TB 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, said the study reported in the journal Emerging Infectious Diseases.

"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 Britain," said lead author of the study Graham Cooke from Imperial College London.

"This sort of analysis will help to improve our understanding of how diseases spread and identify more effective ways to stop them," Cooke noted.

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 Britain to work.

Admission records established that both patients were admitted on the same medical ward in a hospital in Britain for eight days in 2008.

As is typical with TB, the infection did not manifest itself in the second patient until four years later, when he was admitted to hospital and ultimately succumbed to the infection.

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.