Antibiotics could become so ineffective that common injuries such as a grazed knee or a sore throat could kill, the World Health Organization (WHO) has warned.

At the heart of the problem is the increasing resistance to drugs by microbes that cause the most common infections, WHO Director-General Margaret Chan told a meeting of infectious disease experts in Copenhagen, The Independent reported Friday.

"A post-antibiotic era means, in effect, an end to modern medicine as we know it. Things as common as strep throat or a child's scratched knee could once again kill," Chan warned.

"Replacement treatments are more costly, more toxic, need much longer durations of treatment, and may require treatment in intensive care units."

In such an eventuality, a basic procedure such as hip replacement surgery could become too risky to carry out.

Chan said that overuse could gradually render every antibiotic ever produced ineffective, with few incentives for pharmaceutical companies to produce new antibiotics.

"In terms of new replacement antibiotics, the pipeline is virtually dry. The cupboard is nearly bare," Chan said.

"From an industry perspective, why invest considerable sums of money to develop a new antimicrobial when irrational use will accelerate its ineffectiveness before the investment can be recouped?"

Chan said attention given to the growing problem was "inadequate" and "sporadic." She said doctors should prescribe antibiotics only when strictly necessary, and urged authorities to resist using antibiotics in food production.

"At a time of multiple calamities in the world, we cannot allow the loss of essential antimicrobials, essential cures for many millions of people, to become the next global crisis," Chan cautioned.

Chan was speaking at the launch of "The Evolving Threat of Antimicrobial Resistance: Options for Action," a book that warns that medical breakthroughs on flu, HIV and malaria -- among others -- could be ineffective in years to come.

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