In an address for the opening of the World Health Organization's main annual conference Merkel stressed the interconnectedness of global health systems, insisting all nations must work together to root out the problem of antimicrobial resistance — when bugs become immune to existing drugs.
"What is important is to see to it that the effectiveness of the existing antibiotics is ensured and that we use them for purely medicinal purposes," she told diplomats and health experts gathered for the conference.
Merkel said Germany had already agreed to a global action plan for addressing the growing problem of antimicrobial resistance, drafted by the WHO, which is set to be considered by all member states during the two-week World Health Assembly.
"I think each and every country ought to agree such a plan," she told the assembly, stressing that time was of the essence to halt the misuse of antibiotics both for humans and animals.
"We have to avoid these resistances from being built up," she said, pointing out that "it is much more difficult once those resistances actually exist . . . to develop new drugs to combat them."
A WHO report late last month however revealed "major gaps" in all regions of the world in addressing the problem and reining in overuse and misuse of antibiotics.
The UN health agency has warned that without urgent action, the world could be headed for "a post-antibiotic era" in which common infections and minor injuries that have long been treatable once again become killers.
"This is indeed an issue that will be of crucial importance for humankind as a whole," Merkel said.
Learn lessons from Ebola
The German chancellor also spoke of WHO's widely criticized response to the west African Ebola outbreak, which to date has infected nearly 26,800 people and killed more than 11,000 of them.
She stressed the continued vital role of the UN health body, which has been blasted for reacting far too slowly as Ebola cases began multiplying in Guinea, Liberia and Sierra Leone in the first half of 2014.
However, she said, WHO's decentralized structures needed to be rendered "more efficient" to ensure a faster reaction next time.
Merkel said it was a cause for celebration that Liberia, long the hardest-hit country, had been declared Ebola-free and that cases have dwindled in Guinea and Sierra Leone.
But, she said, the fight against Ebola "will only be truly won once we are well-equipped to weather the next crisis, once we have actually learned our lesson from this crisis."