Herbicides like Roundup are driving antibiotic resistance - NZ study

Herbicides help bacteria develop resistance up to 100,000 times faster than normal, a new study has found.

Roundup, Kamba and 2,4-D are the world's most-used herbicides. While they can increase pathogens' susceptibility to antibiotics in some cases, researchers at the University of Canterbury say it's a bad idea to think they can help wipe out the bugs.

"We are inclined to think that when a drug or other chemical makes antibiotics more potent, that should be a good thing. But it also makes the antibiotic more effective at promoting resistance when the antibiotic is at lower concentrations, as we more often find in the environment," said Prof Jack Heinemann.

"Such combinations can be like trying to put out the raging fire of antibiotic resistance with gasoline."

The study, published in journal PeerJ, says antibiotic resistance is "medicine's climate change".

"Caused by human activity, and resulting in more extreme outcomes."

When an antibiotic kills off most bacteria, the bugs it doesn't kill are the ones that produce the next generation - meaning over time, scientists need to come up with stronger drugs to fight back.

There are already calls to ban Roundup's key ingredient, glyphosphate, which has been declared a "probably carcinogen" by the World Health Organisation. Roundup maker Bayer denies this is the case.

New Zealand is at the beginning of a superbug epidemic, microbiologist Siouxsee Wiles told Newshub in August, saying we're about 30 years behind where we need to be.

"The thing that's frightening about them is they are able to share these resistant genes between them. When one of them becomes resistant to antibiotics, it can share that resistance around."

A study earlier this year found Kiwi doctors are overprescribing antibiotics to keep patients happy.

"They don't want to disappoint the patient and they may be not concerned about the fact that the medicines are becoming less and less effective as a result of this wasteful use," said Auckland City Hospital infectious disease physician Mark Thomas.

"The combination of chemicals to which bacteria are exposed in the modern environment should be addressed alongside antibiotic use if we are to preserve antibiotics in the long-term," said Prof Heinemann.