NEW YORK - Only half of 200 or so countries have abided by a pledge to tackle the use of antibiotics with concerted nationwide efforts, threatening lives and crops, particularly in poor countries, expert groups said on Wednesday. 

The report found dozens of countries lack surveillance systems of antibiotic use in humans and animals or have no national policy or legislation to oversee its use

Nearly 200 countries agreed in 2015 to address the issue of resistance to antimicrobials such as antibiotics, which occurs when bacteria, viruses and parasites evolve to adapt to drugs, amid fears of superbug infections with no effective treatments. 

The misuse and overuse of antibiotics can cause illness and death and impact the environment and trade, said the United Nations' Food and Agriculture Organization (FAO), World Organisation for Animal Health, and World Health Organization (WHO). 

But their report said only about half of the nations who signed the 2015 agreement to develop national action plans within two years have done so. 

"This needs to be something that heads of state need to think about," Elizabeth Tayler, head of the WHO's antimicrobial resistance monitoring and national action plan support team, told the Thomson Reuters Foundation. 

She said antibiotics were used to fight child mortality, malaria, tuberculosis and other diseases, but "if those drugs stop working, those gains are very vulnerable". 

"We have over-used them massively, and the more we use antibiotics, the more quickly they become less effective." 

European Union data shows some 700,000 people a year are estimated to die globally because of antimicrobial resistance. 

The report found dozens of countries lack surveillance systems of antibiotic use in humans and animals or have no national policy or legislation to oversee its use. 

Most countries require prescriptions for antibiotics in humans, but less than half limit antibiotics to promote growth in agriculture, it said. 

The report said antimicrobial resistance is "a grave threat to human health and economic development" that is predicted to worsen global inequality as economic costs are borne by poorer countries. 

It also said economists expect significant decreases in international trade of livestock and livestock products. 

The report used information from 154 countries that provided self-assessment surveys of their progress.

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