Food safety

Highest Priority Critically Important Antimicrobials

April 2017

The World Health Organization has classified certain antimicrobial classes as “Highest Priority Critically Important Antimicrobials“ for human medicine in the so called WHO list of critically important antimicrobials for human medicine (CIA list) . The CIA list is intended for public health and animal health authorities, practicing physicians and veterinarians, and other interested stakeholders involved in managing antimicrobial resistance to ensure that all antimicrobials, especially critically important antimicrobials, are used prudently both in human and veterinary medicine. It is intended as a reference to help formulate and prioritize risk assessment and risk management strategies for containing antimicrobial resistance mainly due to non-human antimicrobial use. In the latest version of the CIA list (5th revision, 2016), the “Highest Priority Critically Important Antimicrobials“ are : quinolones, 3rd and higher generation cephalosporins, macrolides and ketolides, glycopeptides, and polymyxins.

The justification for the classification is summarized as follows:

Quinolones

Quinolones are known to select for quinolone-resistant Salmonella and E. coli in animals. At the same time, quinolones are one of few available therapies for serious Salmonella and E. coli infections. Given the high incidence of human disease due to Salmonella and E. coli, the absolute number of serious cases is substantial.

Cephalosporins (3rd and higher generation)

Cephalosporins (3rd and higher generation) are known to select for cephalosporin-resistant Salmonella and E. coli in animals. At the same time, third- and higher generation cephalosporins are one of few available therapies for serious Salmonella and E. coli infections in humans, particularly in children. Given the high incidence of human disease due to Salmonella and E. coli, the absolute number of serious cases is substantial.

Macrolides and ketolides

Macrolides and ketolides are known to select for macrolide-resistant Campylobacter spp. in animals, especially Campylobacter jejuni in poultry. At the same time, macrolides are one of few available therapies for serious Campylobacter infections, particularly in children, for whom quinolones are not recommended for treatment. Given the high incidence of human disease due to Campylobacter spp., especially Campylobacter jejuni, the absolute number of serious cases is substantial.

Glycopeptides

Glycopeptides are known to select for glycopeptide-resistant Enterococcus spp. in food animals (e.g. when avoparcin was used as a growth promoter, vancomycin-resistant enterococci (VRE) developed in food animals and were transmitted to people). At the same time, glycopeptides are one of the few available therapies for serious enterococcal infections. Given the high number of cases, the previously documented occurrence of transmission of VRE to people from food animals, and the very serious consequences of treatment failures in such cases, glycopeptides are classified as being of the highest priority.

Polymyxins

Polymyxins (e.g. colistin) are known to select for plasmid mediated polymyxin-resistant E. coli in food animals. At the same time, intravenous polymyxins are one of few available therapies for serious Enterobactericeae and Pseudomonas aeruginosa multi-resistant infections in people in healthcare settings in many countries, especially in seriously ill patients in critical care. Given the high incidence of human disease due to Enterobactericiae, the absolute number of serious cases where colistin is needed can be considered substantial.