Photo credit: Helen Sessions/Alamy
By Matthew Weaver
What is antimicrobial resistance?
Bacteria and other microbes that cause diseases in humans and animals are becoming increasingly resistant to previously effective drugs. And this is potentially a big problem. The World Health Organisation fears we are heading for a “post-antibiotic era in which common infections and minor injuries, which have been treatable for decades, can once again kill”. One health expert described resistance to antibiotics as “a silent tsunami, crumbling down the pillars upon which modern medicine is built”.
Why is it in the news?
Antimicrobial resistance will become “an even greater threat to mankind than cancer” without global action, according to the UK’s chancellor, George Osborne.
Is Osborne right?
If efforts to curb antimicrobial resistance fail, the number of people who die each year from drug-resistant infections could increase to 10 million by 2050. This would surpass the 8.2 million deaths a year caused by cancer. Dame Sally Davies, England’s chief medical officer, has said the threat was so serious it should be added to the government’s national risk register of civil emergencies.
What is the difference between antimicrobial resistance and antibiotic resistance?
Antibiotic resistance is a narrow term referring to the resistance to antibiotics in bacteria-based diseases such as tuberculosis and hospital infections like MRSA. Antimicrobial resistance is broader covering infections caused by other microbes such as the parasite that causes malaria, HIV and the fungus that causes candida.
How does it occur?
The development of resistant strains is an inevitable consequence of natural selection. It happens when the DNA of micro-organisms mutates and when resistant traits are exchanged between them. The drug expert David Cox explains what happens at the molecular level:
Such mutations can prevent an antibiotic entering the bacteria cell at all, altering the target molecules so that they don’t bind to the antibiotic anymore, or enhancing the efficiency of efflux mechanisms within the bacteria which allow it to simply pump a drug back out again. Certain genes, if acquired, can actively degrade antibiotics, limiting their effectiveness once they’ve entered the cell.
Why is it a problem?
Infections caused by resistant micro-organisms do not respond to normal treatments, resulting in longer illness and greater risk of death. It therefore also increases the cost of healthcare as more expensive treatments are required and longer-term care needed.
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