GPs should cut the amount of antibiotics they prescribe by around a third, says a top researcher who found a drop-off amid last year's Covid-19 response didn't result in more patients turning up at hospital.
A new study, led by the University of Auckland's Associate Professor Mark Thomas, comes amid mounting worry that over-prescribing antibiotics is encouraging the spread of antibiotic-resistant bacteria.
In New Zealand, almost all human use of antibiotics happened not in hospitals but within the community, where they were prescribed by GPs and dispensed by local chemists.
Thomas, an infectious diseases expert at the university's Faculty of Medical and Health Sciences, said our prescribing rates remained comparatively high - and if this continued we could find ourselves at higher risk.
"These antibiotic resistant bacteria that are difficult or impossible to treat will become more common causes of infections in people, and therefore cause tragic outcomes for increasing numbers of New Zealanders," he said.
"The solution recommended all over the world is to use antibiotics much more wisely, only when they are likely to provide a significant benefit, and never when they are likely to provide no benefit.
"Furthermore, because antibiotic use is often associated with side effects, such as diarrhoea, thrush, skin rash and nausea, any antibiotic use that provides little or no benefit means patients may suffer the side effects of antibiotics, despite getting no benefit."
After the Government last year moved to eliminate Covid-19 with a nationwide lockdown and a host of other interventions, Thomas and fellow researchers were eager to see what effect this had on normal antibiotic use.
More importantly, they wanted to see whether a big cut-back was linked to any major adverse outcomes.
That included any spike in the number of patients being admitted to hospitals with pneumonia, rheumatic fever, or peritonsillar abscess or quinsy - the most severe consequence of a bacterial throat infection.
Drawing on a comprehensive national database allowed them to explore how dispensings over New Zealand's national lockdown, along with the following level 2 period, compared with the same weeks in the three years before.
That information was then compared against hospital admissions data from each of the periods.
"We found that the total number of antibiotic courses dispensed by community pharmacies per head of total New Zealand population was approximately 36 per cent lower during 2020 than during 2017, 2018 or 2019," Thomas said.
"This was a huge, prolonged change in antibiotic use."
The data also showed the reductions in antibiotic dispensing were broadly similar for different ethnic groups.
As well, the number of hospital admissions for pneumonia and peritonsillar in 2020 was much lower than previously, while admission rates for rheumatic fever were largely unchanged.
For Māori and Pacific people, specifically, admission numbers for each of the three illnesses were also down on 2019's rates.
"These findings go a very long way towards confirming that a very large proportion of antibiotic prescriptions dispensed in New Zealand confer essentially no health benefit," Thomas said.
If wisely applied, he said making cuts would come at no health cost, would slash the number of patients who suffer side effects, and would make a "very large contribution" to slowing the spread of antibiotic resistant bacteria here.
Thomas added that would thereby "help to prolong the usefulness of the excellent antibiotics that we currently have available".
"[Doctors] should be aiming for reductions of 30 to 40 per cent in the number of antibiotic prescriptions they write, and should be confident that such reductions will not be associated with harm for the patients they see," he said.
"Similarly the people of New Zealand should encourage their health care providers to prescribe antibiotics much less frequently than has been their current practice for very many years."
Despite this, groups including the Royal New Zealand College of General Practitioners and the Best Practice Advisory Centre have recognised the issue over recent years, and suggested ways of reducing usage while prescribing when it's essential.
Dr Bryan Betty, the college's medical director, agreed the problem was a growing one.
In New Zealand, he said that was already being reflected by high rates of antibiotic-resistant MRSA, along with notably high resistance to trimethoprim, an antibiotic used to treat urinary tract infections.
"It is a big, big, issue, and in New Zealand we have to reduce the amount of antibiotics that we prescribe. We're in total agreement."