11 Apr 2017

Siouxsie Wiles on the end of antibiotics

From Jesse Mulligan, 1–4pm, 3:06 pm on 11 April 2017

Time is running out to avoid living in a world where surgery is life threatening and a stubbed toe could lead to a fatal infection, microbiologist Siouxsie Wiles says.

Dr Wiles has written a book on the looming crisis of antibiotic resistance and how it will impact on New Zealand, called Antibiotic Resistance: The End of Modern Medicine?

Human neutrophil ingesting Methicillin-resistant Staphylococcus aureus (MRSA), a bacteria that is resistant to many antibiotics.

Human neutrophil ingesting methicillin-resistant Staphylococcus aureus (MRSA), a bacteria that is resistant to many antibiotics Photo: National Institutes of Health (NIH)

She says the invention of antibiotics in the late 19th century not only greatly increased human life expectancy but enabled us to carry out surgeries and other medical procedures safely.

But she says resistance to antibiotics is increasing - not in humans but in bacteria.

“When bacteria reproduce themselves, they make small mistakes in their genetic material, and because bacteria grow quickly and in great numbers, mutations happen often.

“If they provide an advantage to the bacteria, then they will survive,” Dr Wiles says.

She says even if only 2 in 1 million bacteria are resistant, they are the ones that will take over. These organisms become resistant and then so do all of their descendants.

“That provides a place where they have the advantage and they survive, rather than the ones who aren’t mutants.”

And because bacteria share bits of genetic material with each other, even organisms that have never even seen an antibiotic, by meeting up with the bacteria that has, can become resistant.

It has been some time since we developed any new antibiotics, she says. The armoury available to medicine today is much weaker than it was in the 1960s, but it is this previous abundance of antibiotic options that has brought us to this point.

“Lots of people were developing antibiotics, kind of putting them all in the cupboard. Then doctors would take the ones off that they needed and use them.

“But bacteria would become resistant so doctors would go, ‘OK, well this one’s not working so we’ll put that one away and get another one from the cupboard.’

The problem was that the cupboard wasn’t being “refilled’ when medicines were taken out, she says.

Some antibiotics were unpopular because they had unpleasant side effects. Doctors would have left them in the cupboard to only be used if they had to, she says.

Dr Siouxsie Wiles

Dr Siouxsie Wiles Photo: University of Auckland

“The point is now we’re desperate and we’re using those antibiotics as sort of a last resort.”

And there are even organisms resistant to those last resort antibiotics.

“Last year was the first case in the US of an untreatable super bug… It was resistant to 26 different antibiotics.

“Those cases are going to be small in number at the moment, but they’re going to rise, because people can carry that bacteria in their noses and guts with not having any disease.”

At the moment they’re not causing mass outbreaks, but the number is going to rise, she says.

Recent studies have shown very high prescribing rates for antibiotics in New Zealand, and some studies indicate that perhaps not the right antibiotics are being prescribed.

“There are broad spectrum and narrow spectrum, and often broad spectrum are easier to give. We really need better ways of diagnosing infections so that we can use our medicines more wisely.”

Dr Wiles says work on new antibiotics is a neglected area.

“Because pharmaceutical companies don’t want to invest the huge amount of money it takes to get the drugs to clinical trial, only to have them become redundant several years later because they’re resistant.

“The pharmaceutical industry has mostly pulled out, it’s kind of down to charities and academics.”

Dr Wiles is now working with LandCare research to screen 10,000 New Zealand fungi for medicinal qualities.

It costs about $250 to test each fungus and people are able to sponsor a fungus for testing.

“We’re testing against four different bacteria and we’ve found lots that can kill all of them. And while that sounds great, those are actually not the kinds of antibiotics we’re looking for, because those are those broad spectrums and we’re looking for something much more specific.”