July 23, 2016
A weekly roundup of news on drug resistance and other topics in global health.
Flawed diagnostic tests can kill. Buddha Basnyat, Chair of CDDEP’s Global Antibiotic Resistance Partnership-Nepal, makes that point in reporting on the consequences of widespread use of the 19th century Widal test for diagnosing fever outbreaks in post-earthquake Nepal. Writing in The Lancet Global Health, Basnyat reported that patients with scrub typhus who were misdiagnosed by the Widal test as having typhoid fever were given ceftriaxone, the wrong treatment. Hundreds died unnecessarily. The effective choice is doxycycline—inexpensive and available even in dire post-earthquake settings in Nepal—but it was not used. Typhoid and typhus can be indistinguishable clinically, starkly outlining the need for accurate rapid diagnostic tests for the many serious causes of fever. [Lancet Global Health]
A WHO expert panel updated the list of antibiotics considered most important in human medicine. The list, published in Clinical Infectious Diseases. identifies fluoroquinolones, macrolides, third-generation cephalosporins, glycopeptides and carbapenems as highest priority for protection. The ranking is intended to aid stewardship efforts to reduce use of the listed antibiotics overall, but particularly in the production of food animals. The list has been updated about every two years since 2005. [CIDRAP, Clinical Infectious Diseases]
Zika found to be carried by common Culex mosquitoes, in addition to Aedes aegypti and A. albopictus, a discovery of researchers from Brazil’s Oswaldo Cruz Foundation. The Culex mosquitoes found to carry Zika were from Recife in northeastern Brazil, where Culex are 20 times more common than Aedes aegypti. Whether the species can transmit the virus is unconfirmed. According to Dr. Raman Velayudhan, from the WHO Zika response team, “we also need to know the infection rates of wild-caught Culex compared to Aedes. Studies in other affected countries confirm the transmission by Aedes only. As we learn more, our interventions, recommendations and risk assessments will evolve to reflect new knowledge.” [Washington Post, CNN]
Reducing duration of antibiotic regimens led to 27 percent drop in overall antibiotic use in neonatal intensive care unit, with no detriment to infant safety, according to a study in The Lancet Infectious Diseases. Researchers in a Dallas, Texas, hospital required prescribers to manually extend therapy if needed after an automatic cut-off, and shortened the duration of antibiotic therapy for culture-negative pneumonia and culture-negative sepsis to five days. As a result, antibiotic use decreased by 27 percent, to 70.9 days of therapy per 1,000 patient-days, with no significant effects on infant safety, though there was an increase in the length of average NICU stay from seven to eight days. [CIDRAP, Lancet]
Three antibiotics, while each by itself is ineffective, can overcome bacterial resistance, according to UCLA scientists reporting in Royal Society Interface. Researchers treated in vitro samples of Escherichia coli with one, two, or three antibiotics of different classes from a group of 14 antibiotics. In many cases, adding the third antibiotic enhanced results significantly. Benefits in addition to efficacy include making better use of existing drugs and using lower doses of each antibiotic. Van Savage, one of the authors, said, “People tend to think that you don’t need to understand interactions beyond pairs. We found that isn’t always so.” [UCLA, Journal of the Royal Society Interface]
New guidelines from the Infectious Diseases Society of America and the American Thoracic Society recommend reduced course of antibiotic treatment for adults with two common hospital-acquired infections: ventilator-associated pneumonia and hospital-acquired pneumonia. These infections account for 20 to 25 percent of all hospital-acquired infections and are fatal in 10 to 15 percent of cases. Shortening the course of antibiotic treatment will reduce costs and the potential for antibiotic resistance, while maintaining the benefits of treatment. The guidelines also recommend that hospitals use antibiograms to determine the most appropriate treatment. [IDSA, CIDRAP]
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Image via Alan R Walker / (CC BY-SA 3.0)
