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In 1940, even before penicillin could be rolled out for clinical use, a penicillin-resistant organism was detected by researchers in a sample of Gram-negative E. coli.
Ever since then, man has been in a ongoing battle to create new antibiotics and antivirals faster than nature can find ways to circumvent them.
One of the newest entries onto the antiviral stage has been peramivir (Rapiacta) introduced in Japan in 2010, and used under an EUA (Emergency Use Authorization) here in the United States during the pandemic.
Peramivir is an IV neuraminidase inhibitor, developed by BioCryst, and has been viewed as a potential successor to Tamiflu – particularly for severe cases of influenza.
Today we are hearing of what appears to be a single spontaneous mutation of the new H1N1 virus in a child receiving the IV peramivir therapy.
Spontaneous mutations of this sort, while notable, are not unexpected and are far less serious than a resistant mutation detected in a biologically fit (and circulating) flu strain.
The story from Kyodo News, and then I’ll return with more.
New flu virus resistant to antiflu drug Rapiacta detected in patient
TOKYO, Feb. 22, Kyodo
A genetic mutation of the H1N1 influenza virus resistant to the Rapiacta anti-influenza drug has been detected in a 5-year-old patient, according to the National Institute of Infectious Diseases.
The child has reportedly recovered and has been discharged from the hospital. There are no indications that the mutated virus was transmitted further.
In March of 2010 we learned of another case of peramivir resistance (see NIH: Rapid Development Of Antiviral Resistance In Two Cases) during the fall 2009 pandemic wave.
Our arsenal of antivirals is limited, and some of the new ones in the pipeline are refinements of older drugs, which may prove vulnerable to some of the same forms of resistance.
Overuse of Amantadine, particularly its inclusion into chicken feed during the 1990s to combat bird flu in Asia – has been credited with a dramatic rise in influenza’s resistance to the drug by 2005.
Tamiflu (oseltamivir), released in 1999 proved extremely effective against influenza until 2008, when a resistant version of the old seasonal H1N1 appeared and quickly spread around the world.
Seasonal H3N2 remained susceptible to the drug.
The old H1N1 virus has been replaced by novel H1N1, which fortunately still remains largely sensitive to the drug.
Scientists do worry that over time, the new H1N1 virus could pick up resistance to Tamiflu. And as we’ve seen in these two isolated cases, even newer generations of neuraminidase inhibitors are not immune to resistant spontaneous mutations.
The takeaway message from these reports isn’t that peramivir has already been rendered useless (it hasn’t), but that resistance can develop quickly in rare instances in some people while receiving these medications.
Which is another good reason why getting a flu shot every year is an exceedingly good idea.
It is almost always better to try to prevent an illness, than to have to treat one.
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