ON SEPTEMBER 21st in New York all 193 UN member states agreed to tackle the growing resistance of microbes to antibiotics. Drug-resistant infections now kill more than 700,000 people a year. On current trends, that number may reach 10m by 2050.

One measure of the problem is the Drug Resistance Index, developed by the Centre for Disease Dynamics, Economics & Policy (CDDEP), a think-tank. The index runs from zero, meaning that antibiotics are fully effective, to 100, which means pathogens are fully resistant to them. The index accounts for differences by country in the mix of drugs used and how often they fail to work. In 27 mostly European countries CDDEP has calculated the index at least twice between 2000 and 2014; four to 14 years separate the first and last year for which data required for the calculation were available in any given country. According to the index, the effectiveness of antibiotics has declined in 22 of these 27 countries. Only in Germany and Sweden have things got markedly better. In India, the poorest country in the group, the index suggests that the antibiotics used to treat most bacterial infections fail to work. The pledge of world leaders to go after the problem cannot be timelier.

Correction (September 24th): An earlier version of this piece stated that the number of countries in which the effectiveness of antibiotics has declined is 24. This has been corrected.

Dig deeper:

What to do when the drugs don’t work (May 2016)