FRIDAY, SEPTEMBER 30, 2016

Resistance to Tamiflu may be on the rise

Australian researchers recently published a study that found the pandemic H1N1 influenza A strain may be developing resistance to Tamiflu, also known as oseltamivir, in Australia.

Aeron Hurt, a researcher with the World Health Organization's Collaborating Center for Reference and Research on Influenza in Melbourne, and his colleagues, said the resistance is increasingly being seen among patients never treated with the drug. The research suggests the resistant strains could be fit enough to widely spread throughout the community, MedPage Today reports.

Oseltamivir blocks the influenza's neuraminidase protein and is the most widely used flu drug.

Hurt and his colleagues found in 2011 that the pandemic H1N1 strain demonstrated oseltamivir resistance in a cluster of cases in New South Wales. Out of 182 patients, 29 patients or 15.9 percent had an oseltamivir-resistant virus.

In the recent analysis, Hurt found the overall prevalence of the resistant virus is approximately two percent of isolates tested. The study found, however, an increasing proportion of strains detected in patients who were never treated with oseltamivir. Hurt said the implication of the study is that the resistant virus is being easily transmitted.

"These resistant viruses could spread globally, similar to that seen in 2008 when the former seasonal H1N1 virus developed oseltamivir resistance and spread worldwide in less than 12 months," Hurt said, according to MedPage Today.

Hurt said recent studies in ferrets suggest the new resistant drugs are more transmissible than the strains detected in 2011.

"The widespread transmission and circulation of oseltamivir-resistant (pandemic H1N1) viruses remains a risk in the future," Hurt said, according to MedPage Today. "Close monitoring of resistant viruses in both treated and community patients remains important."

The researchers found the strains were still susceptible to the other drug in the class, neuraminidase inhibitor zanamivir, also known as Relenza.

Hurt will present his findings at the annual meeting of the Australasian Society for Infectious Diseases on Wednesday. Hurt published his findings in the Australasian Society for Infectious Diseases journal, MedPage Today reports.