In light of increasing antibiotic resistance among pathogens, the World Health Organization has revised its global rankings of critically important antimicrobials used in human medicine, designating quinolones, third- and fourth-generation cephalosporins, macrolides and ketolides, and glycopeptides as among the highest-priority drugs in the world.
Peter C. Collignon, MBBS, of Canberra (Australia) Hospital and his colleagues on the WHO Advisory Group on Integrated Surveillance of Antimicrobial Resistance, created the rankings for use in developing risk management strategies related to antimicrobial use in food production animals. According to Dr. Collignon and his coauthors, the rankings are intended to help regulators and other stakeholders know which types of antimicrobials used in animals present potentially higher risks to human populations and help inform how this use might be better managed (e.g. restriction to single-animal therapy or prohibition of mass treatment and extra-label use) to minimize the risk of transmission of resistance to the human population.
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WHO studies previously suggested that antimicrobials which currently have no veterinary equivalent (for example, carbapenems) “as well as any new class of antimicrobial developed for human therapy should not be used in animals.” Dr. Collignon’s WHO Advisory Group followed two essential criteria to designate antimicrobials of utmost importance to human health in the new study: 1. antimicrobials that are the sole, or one of limited available therapies, to treat serious bacterial infections in people and 2. antimicrobials used to treat infections in people caused by either (a) bacteria that may be transmitted to humans from nonhuman sources or (b) bacteria that may acquire resistance genes from nonhuman sources.
The highest-priority and most critically important antimicrobials are those which meet the criteria listed above and that are used in greatest volume or highest frequency by humans. Another criteria for prioritization involves antimicrobial classes where evidence suggests that the “transmission of resistant bacteria or resistance genes from nonhuman sources is already occurring, or has occurred previously.” Quinolones, third- and fourth-generation cephalosporins, macrolides and ketolides, and glycopeptides were the only antimicrobials that met all criteria for prioritization.
“Antimicrobial resistance remains a threat to human health and drivers of resistance act in all sectors; human, animal, and the environment,” the WHO Advisory Group concluded. “Prioritizing the antimicrobials that are critically important for humans is a valuable and strategic risk-management tool and will be improved with the evidence-based approach which is currently underway.”
Read the full study in Clinical Infectious Diseases (doi: 10.1093/cid/ciw475).