Most of the drugs currently in the clinical phase are modifications of existing classes of antibiotics and are only short-term solutions, WHO said.
There are, however, very few potential treatment options. The growing resistant infections pose the greatest threat to health, including drug-resistant tuberculosis (TB) which kills around 250,000 people each year.
There are also very few oral antibiotics in the pipeline, yet these are essential formulations for treating infections outside hospitals or in resource-limited settings, the report said.
"Antimicrobial resistance is a global health emergency that will seriously jeopardise progress in modern medicine," Tedros Adhanom Ghebreyesus, Director-General of WHO, said in a statement on Wednesday.
"There is an urgent need for more investment in research and development for antibiotic-resistant infections including TB, otherwise we will be forced back to a time when people feared common infections and risked their lives from minor surgery," Ghebreyesus added.
Among the newly identified 51 new antibiotics and biologicals in clinical development, only eight are classed by WHO as innovative treatments that will add value to the current antibiotic treatment arsenal, it said.
"Pharmaceutical companies and researchers must urgently focus on new antibiotics against certain types of extremely serious infections that can kill patients in a matter of days because we have no line of defence," noted Suzanne Hill, Director of the Department of Essential Medicines at WHO.
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