In this photo taken on Oct 20, 2010 antibiotics are displayed at a chemist's shop in Mumbai. (SAJJAD HUSSAIN / AFP)

None of the 43 antibiotics currently in development as well as recently approved medicines are enough to combat the increasing emergence and spread of antimicrobial resistance, the World Health Organization cautioned on Thursday.

Drug resistance is driven by the misuse and overuse of antibiotics and other antimicrobials, which encourages bacteria to evolve into "superbugs" and find new ways to beat the medicines

Almost all new antibiotics brought to market in recent years are variations of drug classes discovered decades ago, according to a WHO report released on Thursday, underscoring just how insufficient they may be in tackling antimicrobial resistance (AMR).

Drug resistance is driven by the misuse and overuse of antibiotics and other antimicrobials, which encourages bacteria to evolve into "superbugs" and find new ways to beat the medicines. Previous studies have estimated AMR will kill tens of millions of people every year after 2050.

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Out of the 43 antibiotics in development, the WHO said 26 drugs target the 13 most dangerous “superbugs”. But the health agency said most of these antibiotics are derivatives of existing classes, which could result in “rapid emergence of drug-resistance.”

The report said the impact of AMR is now most severe in poorer countries and among the very old or very young, with an estimated 30 percent of newborns with sepsis dying from bacterial infections that are resistant to first-line antibiotics.

“The persistent failure to develop, manufacture, and distribute effective new antibiotics is further fueling the impact of antimicrobial resistance and threatens our ability to successfully treat bacterial infections,” said Dr. Hanan Balkhy, WHO Assistant Director General.

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The 2020 annual report reveals a near “static” pipeline, the WHO said, as few antibiotics have been approved by regulatory agencies in recent years, and with big pharma companies losing interest in antibiotics development as it is not seen as profitable.

Large drugmakers Novartis, Bristol Myers Squibb and AstraZeneca Plc have abandoned development of their antibiotic programs in the past few months.

However, for the first time, the agency has included an overview of non-traditional therapies to weaken bacteria, including bacteria-eating viruses called bacteriophages, and immune therapies.