Tackling Superbugs

NEW ways of dealing with an old enemy are being sought by the Ministry of Health as part of its ongoing commitment to improving the quality of New Zealanders' health services.

Draft guidelines for tackling methicillin resistant staphylococcus aureus (MRSA), a bacterium which is increasingly common in the commmunity and can cause havoc when it spreads within a hospital or rest home, have been drawn up by an expert group convened by the Ministry of Health.

"MRSA is one of the major quality control problems facing hospitals all over the world," spokesman Dr Don Matheson said. "Not only can it slow the recovery of individual patients but it can force the closure of wards or operating theatres and completely disrupt the normal daily business of a hospital."

"We can't eliminate it but we can do our best to minimise its spread and impact. To that end the group has made a first pass at updating guidelines first promulgated by the Department of Health in 1992. We're now sending these to a wider group of people working in infection control, harnessing their collective experience and brainpower to come up with the best advice we can. This will encompass control in the sorts of community settings in which healthcare is delivered as well as in hospitals. Once we've received feedback from this wider group we will be releasing a consultation document to ensure other interested parties can provide input into the guidelines."

MRSA is increasing in the community, which in turn increases the chances of someone carrying it into hospital where it can have serious consequences for people whose immune systems are already under stress.

"An outbreak can be triggered by something as simple as someone with the bug who sits on the patient's bed - lots of us carry staphylococcus in our noses, and wouldn't necessarily be sick or know that we had it," Dr Matheson said.

He said microbiologists now recognised the inevitability of bacteria mutating and developing a resistant strain at some point. "To slow down the need for newer and newer antibiotics, some of the basic hygiene and infection control proceedures need reiterating, strengthening and monitoring."

Dr Matheson said updating the guidelines was a key recommendation of the recent Integrated Approach to Infectious Diseases. The consultation document will be released in mid-April and the final version will be be available mid-year.

ENDS

Background

Organisms that are resistant to commonly used antibiotics are a growing global concern. This is not only because infection involving resistant organisms increases the complexity and cost of treatment but also because in some cases the infection may become untreatable.

Generally New Zealand has relatively low levels of antibiotic resistance, but there are concerns about some key pathogens such as methicillin-resistant staphylococcus aureus (MRSA). This is why the Ministry of Health is redrafting Guidelines for its control.

The extent of the problem

Staphylococcus aureus is a natural inhabitant of skin and mucous membranes such as the nose and perineum, and about 30% of adults are colonised. Simple colonisation has no adverse impact on healthy people, but in certain situations it may cause disease, including skin abscesses, post operative wound infections, septicaemia and pneumonia, particularly in people who are already ill. Fewer antibiotics can be used to treat methicillin-resistant staphylococcus aureus, so it is desirable to minimise its occurrence.

The incidence rate of methicillin resistance among S aureus isolated in NZ is relatively low. In 2000, based on data collected and collated from hospital and community labs throughout NZ, the rate of methicillin resistance was approx 7% (actual 6.9%). In comparison, rates in some countries, such as parts of Australia, the United Kingdom, and the United States, are as high as 40-50%. At the other extreme, several countries in northern Europe (eg, Denmark, the Netherlands and the Scandinavian countries) have rates as low as 1%.

Since the mid-1990s, the incidence of MRSA has been increasing in NZ. Between 2000 and 2001, there was a 38% increase in MRSA isolations (from 5148 isolations to 7092). Back in 1995, there were just over 1000 isolations during the year. During the last few years, the increase in MRSA rates has been mainly driven by the spread of a multiresistant, hospital-acquired strain ? EMRSA-15. This strain originated in Britain, appears to be very transmissible, and now accounts for about 40% of the MRSA in NZ.

Is widespread antibiotic usage associated with the increase in MRSA?

Widespread use of antibiotics in humans is associated with an increase in antibiotic resistance. Recent promotional campaigns to reduce unnecessary antibiotic prescribing in New Zealand have reduced the use of antibiotics, and such campaigns will continue.

Some strains of MRSA spread very easily. Once such strains are introduced into our hospitals, for example on patients transferred from overseas' hospitals, they are often difficult to completely eliminate.

It is highly unlikely that methicillin resistance in S aureus isolated from humans is connected with the use of antibiotics in animals. MRSA are rare in animals in NZ ? the surveillance of resistance among bacteria isolated from animals indicated that only 0.7% of S aureus isolated from animals in 2000 were methicillin resistant. Studies have actually found that MRSA in animals are likely to have come from man, not vice versa. Moreover, it is widely accepted that all MRSA strains that affect humans have evolved from a very limited number of ancestral clones.

Surveillance

Surveillance of MRSA ,and other infectious diseases, is important to characterise the epidemiology or pattern of infections and identify risk factors. Our current surveillance has helped define which MRSA strains are more easily transmitted. This enables HCFs to taken extra stringent infection control measures when one of these strains is isolated.

NZ has had very comprehensive, on-going national surveillance of MRSA since the first reported case in 1975. All isolates are referred to ESR so that they can be characterised and the epidemiology of MRSA in NZ analysed and described. Data on MRSA are regularly disseminated and published. The Ministry of Health funds this surveillance.

Such comprehensive, on-going surveillance is rare. For example, Australia and the United States do not have such national surveillance systems. However, some of the northern European countries with low rates have intensive surveillance systems.

Control

MRSA is highly transmissible in health care settings: hospitals and long-term care facilities. It is transmitted from person-to-person, most often on the hands of health staff, and also, but probably less commonly through the air by such activities such as bed-making. Some strains can be difficult to control.

It is desirable to focus control efforts in health and long-term care facilities. Good infection control procedures, in particular scrupulous attention to hand hygiene, are the key to minimising the risk of MRSA and other antibiotic-resistant organisms. These are the responsibility of each facility.

The draft guidelines propose key activities for control covering: · Infection control procedures · Criteria for screening of patients and staff · Management of patients and staff with MRSA · Management of outbreaks · Surveillance · Laboratory procedures.

The guidelines will be finalised by 30 June after consultation.

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