KEY POINTS:
Five wards at North Shore Hospital have been designated "outbreak wards" to help control an explosive increase in the prevalence of a hard-to-treat bug.
More than 350 patients of Waitemata District Health Board have this year been found to have the so-called "ESBL-producing bacteria", which are resistant to a range of antibiotics.
Nine Waitakere Hospital patients with the bacteria were in isolation last night, but the board management did not have a number for North Shore Hospital.
Many patients being admitted to North Shore Hospital are put in the outbreak wards until screening test results show if they have the bacteria. Those with positive results are quarantined in isolation areas, either alone or with other affected patients.
The number of patients found to have the bacteria had been increasing slowly but was under 20 a year - until last year when the figure reached 50. Since then it has exploded.
The board's deputy chief medical officer, Anne Kolbe, said yesterday it had started to test many patients on admission from mid-year, after a rapid increase in the numbers affected.
She said fewer than 10 per cent of those who were "colonised" by the bacteria on their skin developed an infection from them and these people were often already sick or their immune system had been weakened by treatments for other conditions. The rest were carriers who were not personally affected by the bacteria.
No one had died from infection by the bacteria during the outbreak, which was under control and waning, she said. "Our hospitals are safe."
The hospitals are reminding staff and visitors about the importance of hand-hygiene, are keeping carriers and those infected isolated from other patients, and have stepped up cleaning. "We've studied the bacterium involved and we know that it is a specific mutation that occurred in our community," said Anne Kolbe.
The numbers of patients had peaked at 91 in September, declining to 54 last month and was on track to be even fewer this month.
"A significant part of the large jump is because we have started to do something we have never done - we have started to screen for the purposes of putting together cohorts of colonised and non-colonised patients."
An Auckland City Hospital spokeswoman said its outbreak of vancomycin-resistant enterococci (VRE) was "still being managed. We haven't eradicated it yet".
