Resistance to antibiotics is growing and could pose a greater threat to human survival than climate change, Britain's chief medical officer has warned.

Dame Sally Davies says at least ten million people worldwide could die every year if antibiotic use is not decreased.

The discovery of penicillin in the 1940s signalled the dawn of the antibiotic era and revolutionised therapeutic medicine forever.

Antibiotics are compounds capable of fighting bacterial infections. Yet dangerous bacteria are becoming increasingly resistant to them.

Antibiotic consumption in the past 20 years has increased dramatically, with the NHS reporting a rise of 65% in 76 countries across the world between 2000 to 2015.

Brexit deals could increase antibiotics in food chain

Overuse of antibiotics has serious consequences leading to an era where they do not work to fight disease anymore.

Davies says antibiotic resistance is the biggest threat.

"Like climate change, we humans are doing it to ourselves, but it could kill us before climate change does. It is a very important area. And we are underinvesting in sorting it out. It seems that humanity is not very good at sorting out a problem that's growing very slowly."

She added: "At least ten million could die every year if we don't get on top of this. And that is more than die at the moment of cancer and diabetes. So this would be a serious issue."

She also expresses concern that potential post-Brexit deals with countries like the United States could allow very high levels of antibiotics to enter the food chain.

"We should not be importing beef or other animals where antibiotics have been misused. And growth promotion is a misuse in my book because it leads to problems across the world," Davies says.

The use of growth hormones in US beef has led to an EU ban on its import by member states.

Antibiotics in chicken

In the US, 70% of all antibiotics are consumed by farm animals according to the Food and Drug Administration.

Strict EU regulations on farming have led to a significant decrease in antibiotic use by the UK animal sector, including a dramatic drop in antibiotic use in chickens.

Davies' concerns are echoed by the Chief Executive Officer of the UK's Soil Association, Helen Browning.

In the UK, the preventive use of antibiotics by organic farmers is not allowed.

"If we do the wrong trade deals with the (United) States, we could end up bringing in meat and dairy products that come from systems where they are using many times more antibiotics than we are here," Browning says.

The US government says it wants to negotiate a trade deal with the UK within a year of it leaving the European Union.