Florida Keys News
Monday, October 17, 2016
Oxitec: Drug resistant bacteria not a threat

In a response letter to a petition filed by Key West doctors, officials from biotech firm Oxitec said drug resistant bacteria on genetically modified mosquitoes have been studied thoroughly and are not a threat.

Oxitec and the Florida Keys Mosquito Control District have proposed a test release of genetically modified Aedes aegypti mosquitoes as part of a mosquito control project.

Dr. John Norris has been calling on the district board to not approve its agreement with Oxitec until there is a review of how genetically modified mosquitoes could lead to an increase in resistance to the drug tetracycline — a medical antibiotic that will also be used in producing the mosquitoes.

Norris has received the signatures of about 30 local doctors who support his request for further review of the non-medical use of tetracycline. The doctors specifically wanted to look at the bacteria Staphylococcus aureus for antibiotic resistance.

Oxitec principal scientist Derric Nimmo said any risk of antibiotic resistance is “negligible.”

“The problem of antibiotic-resistant S. aureus is a significant challenge to health and one that we take very seriously. So does the Food and Drug Administration. The FDA-led review team, which also included experts from the Centers for Disease Control and Prevention and Environmental Protection Agency, looked specifically into this issue and concluded that ‘the likelihood of the adverse effects associated with development of anti-microbial resistance is extremely low and the risk is negligible,’” Nimmo said in a letter to Norris.

“We have also been consulting with and continuing to discuss this question with experts on this subject, all who agree with the above conclusions.”

Tetracycline is a key component in ensuring Oxitec’s genetically modified mosquitoes die after being born. The antibiotic acts as a switch to control the mosquito’s other genes.

During the rearing process, the mosquitoes are given tetracycline, which enables them to survive and reproduce in the facility. But when the males are released into the wild, their offspring can’t access the antibiotic in the quantities needed to survive, so they die before reaching adulthood.

The mosquitoes may die, but Norris is concerned that bacteria inside the mosquitoes would live on and become immune to antibiotics.

The petition requested culturing of the mosquitoes and bacterial identifications and sensitivities related to tetracycline, with any examples to be sent to Dr. Barry Kreiswirth at Rutgers University. The letter also requested a nasal swabbing study following the test release.

“Results are our focus,” Norris said. “If resistance does exist we would withdraw the petitioned concerns publicly, providing the results are factored into any release and follow up study.”

Norris called Nimmo’s response, “very disappointing.”

“I guess I will communicate with the physicians again,” Norris said. “We will voice our concerns and continue to ask for cooperation and data.” 


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