Researchers track evolution of TB superbugs in PNG

12 February 2018

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Researchers say there is an urgent need for rapid diagnostics to prevent the geographical spread of multi-drug resistant tuberculosis (TB) in Papua New Guinea (PNG).

A joint University of Queensland and Queensland Health-led team has completed the first genetic analysis of TB strains circulating on PNG’s Daru Island, a major hotspot for TB outbreaks on Australia’s doorstep.

UQ Institute for Molecular Bioscience (IMB) Associate Professor Lachlan Coin said by retrospectively constructing a molecular ‘clock’, researchers found one strain had developed mutations against 12 drugs by 2009, rendering all first- and second-line treatments ineffective.

“Standard treatments would not help people with this extensively drug-resistant strain, and those patients would remain infectious until an effective treatment was given,” Dr Coin said.

“Other strains have acquired resistance to a varying number of the drugs contained in standard treatments.

“PNG health services urgently need the tools to rapidly assess which drugs will work for individuals, based on the particular bacteria involved.”

The island, with a population of less than 17,000, had 125 confirmed cases in 2016, one of the highest rates of incidence of multi-drug resistant TB in the world.

The study found the strains of TB on Daru had evolved from a common ancestor circulating since the 1940s.

PNG Central Public Helath Laboratories Director Dr Evelyn Lavu said it was the first time there had been  a detailed understanding of the strains located in a proven MDR-TB hotspot.

“Translation of these findings to the clinic level is our next challenge," Dr Lavu said.

UQ PhD student, Arnold Bainomugisa said untreated TB was highly infectious, spreading through coughing, sneezing and even talking and singing.

“Delays in detecting and effectively treating drug resistant cases increase the potential for its spread to adjacent geographical areas, including the PNG capital of Port Moresby,” Mr Bainomugisa said.

“The rate of transmission would be amplified in larger populations if highly effective public health programs were not in place.”

Dr Chris Coulter from Pathology Queensland’s Mycobacterium Reference Laboratory said there were no resistance mutations associated with the most recently approved TB drug detected in the Daru Island samples.

“Bedaquiline is more expensive than standard treatments, but it’s crucial that it is available in a timely way for those patients who need it,” Dr Coulter said.

“The study also highlighted the need to carefully manage treatment with new TB drugs to prevent resistance developing.

“Any TB requires a lengthy treatment regime, and in the case of extensively drug resistant strains it can take more than two years of treatment.”

The study is published in the Journal of Microbial Genomics.

Media enquiries: IMB Communications, communications@imb.uq.edu.au, 07 3346 2134, 0418 575 247

 

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