At 361 patients and staff, the Waitemata DHB reported the greatest number of people affected in the three financial years to June 30 last year. These were all norovirus cases, as were the 198 patients and staff affected at Counties Manukau DHB.
At Waikato DHB, in addition to the majority of cases, which were norovirus, there were two outbreaks of superbugs: one was CRE (carbapenemase-resistant enterobacteriaceae), affecting six patients; the other was ESBL (extended-spectrum beta-lactamase-producing bacteria), affecting 10 patients last year.
At Auckland DHB, 21 patients and 22 staff had norovirus. A further 41 patients had a superbug: two had MRAB, 24 had vancomycin-resistant enterococci in December 2012, and 15 had multi-resistant klebsiella pneumoniae between January and July 2012.
Dr Roberts said both MRAB patients were colonised by the bacteria - it was detected in their phlegm or saliva - but did not cause them an infection.
"We didn't have to treat them but if they had got a serious infection and we had to treat them we would have struggled ... There is high mortality with it."
"The patient got transferred [from an intensive care unit] and it wasn't picked up on our routine screen, but they came ventilated and we picked it up that way, it was in their respiratory secretions."
"The patient was transferred from overseas with it - we don't have homegrown strains at all - and unfortunately transferred it to one patient but that was it. We were very aggressive in our approach on managing that."
An investigation did not discover how the bacteria got to the second patient.
"I presume in all honesty there had to be a breach in best practice, but we never determined what it was."
Dr Roberts said MRAB turned up at Auckland Hospital occasionally in patients who brought it back from overseas hospitals.
The two patients were isolated from other patients, staff attending to them used special precautions such as protective goggles, their rooms underwent a special clean after the patients left, and their national health index numbers have been tagged with an alert.
"As you get better, if you don't need to have a ventilator or tracheostomy to assist you breathing, you get rid of these germs over time."
Lack of vigilance on antibiotics
Government officials have admitted to a "lack of surveillance" of antibiotic use, and that there has been "little, if any" review of antibiotic-resistance policy.
Infectious disease experts say New Zealand's strategy to combat antibiotic-resistant bacteria harmful bacteria is "missing in action".
Making a plan is considered especially important for New Zealand because of its high use of antibiotics compared with other developed countries.
Associate Professor Mark Thomas and colleagues say in the New Zealand Medical Journal that there has been "no visible coordinated strategy around antimicrobial resistance in New Zealand".
They list antimicrobial-resistance threats to have emerged in New Zealand, including high rates of staphylococcus aureus resistance to fusidic acid, the detection of resistant campylobacter in poultry and people, and the transmission of bacteria resistant to carbapenems, a group of last-resort antibiotics.
Dr Thomas told the Herald New Zealand must develop a strategy to significantly reduce antibiotic use and to make greater use of the narrow-spectrum types in preference to those which target a broader range of harmful bacteria.
The Government has committed to enacting a national plan on antimicrobial resistance by May 2017, in response to the international request of the World Health Organisation in 2011.
In a Health Ministry paper obtained under the Official Information Act, officials told ministers of the effect of the 2010 discontinuation of the Antimicrobial Resistance Advisory Group.
"As a result, in recent years little - if any - antimicrobial resistance policy review has occurred despite a growing global concern over new and emerging antimicrobial resistant organisms.
"For example, at a national level, data from the surveillance of resistance is not being used to formulate and then monitor policies to manage the emergence and spread of antimicrobial resistance."Another ministry group monitors the number of infections linked to healthcare, the paper says.
"However, some clinicians consider that the relationship of healthcare-associated infections with antimicrobial use and antimicrobial resistance is only a very small part of the overall picture.
"There is a lack of surveillance of antimicrobial consumption, particularly in the community setting where most prescribing occurs."
One of the authors of the ministry paper, chief medical officer Dr Don Mackie, told the Herald the ministry had contracted the Institute of Environmental Science and Research (ESR) to analyse the impact of antibiotic prescribing on resistance in New Zealand.
"Antimicrobial resistance continues to be a high priority for the ministry."
The paper, written when Tony Ryall was Health Minister, floated the idea of a health target to compare hospitals and regions on their use of antibiotics. Mr Ryall last year dismissed the idea to the Herald, but said benchmarking antibiotic use against best practice was being considered.
Dr Thomas said ministerial targets, such as the one to encourage increased immunisation of children, had proven their ability to make changes.
