Weekly Digest: Thirty percent of U.S. outpatient antibiotic prescriptions unnecessary

Wolbachia: A microbiological tool in the fight against dengue fever and possibly Zika. Writing on the CDDEP blog, Research Analyst Anjali Merchant examines research on how Wolbachia—a bacterium that can be made to infect Aedes aegypti mosquitoes artificially in the laboratory—has been proven to limit transmission of dengue, and notes that it may also be able to limit transmission of other viruses, including Zika. Merchant writes that as the mosquito continues to spread, adding Wolbachia to the,vector control armamentarium—especially in the face of increased insecticide resistance among mosquitoes and urbanization—may be another way to limit disease spread. Brazilian researchers reported success in using Wolbachia to limit Zika virus transmission this week in Cell Host and Microbe. [CDDEP, Cell Host and Microbe]

Thirty percent of outpatient oral antibiotic prescriptions in the United States are unnecessary, report researchers from the Centers for Disease Control and Prevention and Pew Charitable Trusts in JAMA. Two large CDC surveys of U.S. outpatient centers in 2010 and 2011, which included data from 180,000 patient visits, revealed that more than 12 percent of visits resulted in an antibiotic prescription, of which 30 percent were not needed. Acute respiratory conditions were the diagnosis most likely to elicit unnecessary prescriptions, accounting for 221 antibiotic prescriptions per 1000 people annually, of which only 111 per 1000 were appropriate, according to current guidelines. [JAMA, The Washington Post]

The European Medicines Agency has recommended that ceftazidime/avibactam (brand name Zaviceftra) be approved for treatment of drug-resistant infections. The recommendation comes from EMA’s Committee for Medicinal Products for Human Use (CHMP), and will be sent to the European Commission for a final decision. The drug, marketed in the United States under the name Avycaz, was approved by the U.S. Food and Drug Administration in February 2015 to treat complicated urinary tract infections and complicated intra-abdominal infections. [PharmaTech, CDDEP]

An outbreak of Listeria linked to frozen vegetables has been reported in three U.S. states; eight adults have been diagnosed, two of whom died. The outbreak is linked to frozen vegetables produced by CRF Frozen Foods, based in Washington state. Six patients were diagnosed in California, and one each in Maryland and Washington. Whole genome sequencing of the bacteria found that seven patients were infected by frozen corn products and the eighth patient by frozen peas. CRF has recalled of all of its organic and traditional frozen fruit and vegetable products—358 products sold by 42 different brands—and shut down its Pasco, Washington facility temporarily to conduct a review of operations. [CIDRAP, CDC]

A proposed voucher system to reward antibiotic innovation is flawed, but could be improved. The recent voucher proposal is intended to stimulate antibiotic innovation by awarding companies that develop a new antibiotic a transferable “voucher” that can be used to extend the patent exclusivity of an existing product. Writing in Health Affairs, Kevin Outterson and Anthony McDonnell argue that vouchers have some advantages—namely, not requiring annual appropriations from Congress—but that the system creates a mismatch between the public value of antibiotic innovation and the value of the voucher to the company. This could eventually result in higher drug prices and less antibiotic innovation, depending on how vouchers are awarded, preserved and valued. The inefficiencies can be limited (though perhaps not eliminated) by 1) on the antibiotic side, rewarding according to the social value of the new antibiotic and 2) on the reward side, rewarding based on potential revenues to be gained by patent exclusivity extension, rather than a set time period regardless of estimated revenue. [Health Affairs]

Zika virus is likely to become a “constant low-level threat” in the United States, writes Maryn McKenna in National Geographic. A combination of frequent travel to and from the mainland United States, rising temperatures conducive to mosquito survival and growing mosquito populations all but ensure that Zika is here to stay. It will not be an epidemic, but an endemic, persistent threat that waxes and wanes, like West Nile Virus. A small NIH-sponsored vaccine trial may start sometime next year, but a ZIka vaccine is still years away, and funding for research is heavily constrained—Congress went to recess this week for a second time without voting on funding for Zika. According to Jose Esparza, president of the Global VIrus Network, “We don’t know the future course of the epidemic of Zika, but we have to be prepared for the virus to be present for years.” [National Geographic]

HIV-infected women in sub-Saharan Africa are among the most vulnerable to malaria infection—but also among the least protected. The challenge of this situation was explored  in PLOS Medicine by researchers from Spain, Mozambique, Switzerland and the United States. The current WHO recommendation for pregnant women in areas with stable malaria transmission is Intermittent Preventive Treatment with sulfadoxine-pyrimethamine, a drug that is contraindicated for HIV-positive women taking cotrimoxazole to prevent opportunistic infections. This leaves them uniquely vulnerable to malaria infection. The researchers write that need is urgent to identify antimalarials that can safely prevent malaria in these HIV-infected women. [PLOS Medicine]

Can you tell if there are antibiotics in your pizza? Bloomberg reporter Deena Shanker investigates what companies mean when they claim to eliminate antibiotics from meat products—and whether consumers can actually tell the difference. She found that amongst the many U.S. fast food companies that have made similar claims, nearly every one has a different way of implementing their policies, and many are implemented with almost no verification or oversight. A representative of ShareAction, a consumer group that recently co-led an investor campaign to minimize use of antibiotics in livestock, noted investment concerns: “What’s the point of having that policy if you can’t prove how you’re implementing it?” [Bloomberg]