AMR occurs when bacteria, viruses, fungi and parasites change over time and no longer respond to medicines, making infections harder to treat and increasing the risk of disease spread, severe illness and death. The cost of AMR to national economies and their health systems is significant as it affects productivity of patients (or of their caregivers) through prolonged hospital stays and the need for more expensive and intensive care.

Without effective tools for the prevention and adequate treatment of drug-resistant infections and improved access to existing and new quality- assured antimicrobials, the number of people for whom treatment is failing or who die of infections will increase.

In 2015 the WHO launched the Global Action Plan on AMR. Despite the increased awareness in the past few years, few actions have been taken to reduce incidence of infections and to optimise antimicrobial use. With the 2017 update of the Model List of Essential Medicines, the WHO has proposed a new classification of antibiotics, the AWaRe classification (Access, Watch, Reserve), in the context of a comprehensive review of the optimal antibiotic choices for many common infectious syndromes in adults and children.  In 2019, the classification was further reviewed and expanded to the most available antibiotics and a fourth category “Discouraged antibiotics” was added.

The WHO General Program of Work 2019-2023 has adopted a new indicator based on AWaRe: Access>60% (i.e., the proportion of Access antibiotics at a country level should be more than 60% of overall antibiotic use). This indicator will become a common global target to reduce AMR by favouring the use of ACCESS narrow spectrum antibiotics in comparison to broad spectrum WATCH and RESERVE ones.

The WHO analyses Consumption data through the WHO GLASS (Global Antimicrobial Resistance Surveillance System). Unfortunately, most hospitals in low-middle-income countries (LMICs) do not have adequate electronic tools to provide reliable data linking indication to consumption data. As for community data, the most available antibiotic consumption data do not have a defined link to a specific indication.

The period 2000-2015 recorded a stable use of Access antibiotics in high-income countries (HICs), while it has increased in LMICs and LMs; in upper middle low- and middle-income countries (LMIC-UM) broad-spectrum Watch antibiotics use has remarkably increased.
At present no standards are agreed upon neither for “unit of resistance” nor for “unit of antibiotic”. This is a prerequisite to develop prediction models, which should also include exposure and resistance with broad-spectrum and narrow-spectrum antibiotics, both in HICs and in LMICs settings. The example of climate change modelling could help to pave the way for a new model predicting trends of antibiotic resistance.

To counter AMR, some strategies should be implemented and some issues deserve extra attention:

• Clinical AMR surveillance should be developed, in parallel with microbiology-based surveillance, including efficacy studies in sentinel sites (similar to malaria, TB and other infections), thus allowing to gather clinical information on diseases, severity, pre-treatment and outcome.
• It is necessary to improve the models of optimal prescribing, which should include “ideal” patterns of community and hospital use, risk adjusted for disease burden and varying levels of resistance, highlighting what is “antibiotic modifiable” mortality and morbidity
• More attention is to be drawn to hospital-acquired infections; in high-income countries, around a quarter of bloodstream infections is hospital-acquired, while in low-middle income countries, over 90% of antibiotics are used in the primary healthcare setting for infections which could be safely treated with Access antibiotics.
• It is essential to develop and implement more formal policy goals and clear targets focusing on safely reducing Total and oral Watch antibiotic use, as well as AWaRe-based tools to monitor outcomes.

• WHO Global action plan on antimicrobial resistance
• The 2019 WHO AWaRe classification of antibiotics for evaluation and monitoring of use
• WHO 2020 antibacterial agents in clinical and preclinical development: an overview and analysis
• Hsia Y, Lee BR, Versporten A et al. Use of the WHO Access, Watch, and Reserve classification to define patterns of hospital antibiotic use (AWaRe): an analysis of paediatric survey data from 56 countries. Lancet Global Health, 7: e861–71. DOI: 10.1016/S2214-109X(19)30071-3