Kiwis' use of antibiotics has soared, indicating widespread inappropriate use for viral coughs and colds, experts say.
Antibiotic use increases by 43 per cent in wintertime and this, plus a 49 per cent increase in consumption of antibiotics prescribed in the community over nine years, is fuelling fears about the increasing resistance of dangerous bacteria to the life-saving drugs.
Experts say doctors are prescribing inappropriately, partly driven by patient demand.
"It is extremely likely that most of these prescriptions were unnecessary because antibiotics provide no benefit to the overwhelming majority of patients with these conditions," Auckland University infectious diseases specialist Associate Professor Mark Thomas says.
The wintertime increase in usage is an accepted measure of the appropriateness of community antibiotic prescribing, he says.
"Using this measure, during 2014, the quality of community antibiotic prescribing was markedly better in some DHBs [district health boards], such as the West Coast DHB, than it was in others, such as the Counties Manukau DHB."
"Most of the increased number of winter prescriptions would have been dispensed to patients with minor self-limiting infections such as colds, bronchitis and influenza."
The Ministries of Health and Primary Industries are writing a national action plan to help tackle the growing global threat of antibiotic resistance.
"New Zealand's antimicrobial dispensing has increased dramatically ...," says Dr Stewart Jessamine, the director of protection and regulation at the Ministry of Health.
The increase in New Zealand's use of the drugs is revealed in the first annual report on consumption of antibiotics prescribed in the community, commissioned to underpin the action plan.
The report, produced by the Institute of Environmental Science and Research (ESR), found our usage increases greatly in the wintertime, indicating high levels of inappropriate prescribing by GPs.
Across all health districts, the median increase in winter use was 41 per cent compared with summertime and was greatest, at 53 per cent, in Counties Manukau. The wintertime rise indicates use of antibiotics to treat coughs and colds that are caused by viruses and not susceptible to antibiotics.
Over-use and wrong use of antibiotics in humans and animals - and even appropriate use - contribute to the evolution by harmful bacteria of ways to survive treatment.
Some strains of infections such as pneumonia, gonorrhoea and tuberculosis are becoming harder to treat because they have developed resistance to some of the drugs used against them. Hospitals have to deal with superbugs like vancomycin resistant enterococci (VRE) and extended spectrum beta lactamases (ESBLs).
The ESR study shows that nationally we used 17.8 doses of antibiotics a day for every 1000 people in 2006.
This rose to 25.8 doses per 1000 in 2014. Our consumption was slightly higher in 2013 and this put us above 22 of 29 European countries studied.
Last September, United Nations General-Secretary Ban Ki-moon said antibiotic resistance posed a fundamental threat to global health and safety.
England's chief medical officer Dame Sally Davies has told doctors they must stop prescribing antibiotics for viral coughs and colds, to avert the "catastrophic threat" of antibiotic resistance.
The Australasian College of Physicians predicts that my mid-century, on current trends, deaths caused by antibiotic resistance could exceed cancer deaths.
South Auckland GP Professor Bruce Arroll said Counties Manukau's high rankings in antibiotic prescribing reflected its nationally high proportion of high-risk patients.
But he said all health districts should be lower and doctors must lead a culture change to persuade patients away from the common expectation that they need an antibiotic.
"There's research in Dunedin showing 50 per cent of New Zealanders get an antibiotic every year, which is totally outrageous."
Percentage increase in community prescriptions of antibiotics in wintertime, compared with summertime, by district health board area and NZ median: