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Disease WAtch

Changes to the community-associated MRSA program and what they mean for GPs

Methicillin-resistant Staphylococcus aureus (MRSA) are characterised as community-associated (CA-MRSA) or healthcare-associated (HA-MRSA) strains based on molecular typing. The strains can be further classified according to whether the gene for Panton-Valentine leukocidin (PVL) is present. PVL is a toxin that can be present in any S. aureus isolate and is associated with the destruction of white blood cells.

Compared to HA-MRSA strains, CA-MRSA strains have distinct clinical, epidemiological and bacteriological characteristics. CA-MRSA strains have adapted to survive and spread successfully in the community environment, often causing skin and soft-tissue infections in otherwise healthy people.

In 2007, microbiologists and scientists raised their concern to the Communicable Disease Control Directorate (CDCD) about the increasing incidence of PVL-positive cases of CA-MRSA in Western Australia (WA). Scientific literature at the time indicated that PVL-positive strains posed a greater threat than PVL-negative CA-MRSA strains due to inherently greater virulence. To minimise the impact of PVL-positive CA-MRSA in WA, an intensive “search and destroy” CA-MRSA control program was undertaken, coordinated by the CDCD. This program required follow-up of all cases of PVL-positive CA-MRSA by the public health units (PHUs), including screening of household contacts, and decolonisation of cases and those household contacts who screened positive.

Since its inception in January 2008, the program has been reviewed annually by an Expert Advisory Group (EAG) consisting of clinical and public health specialists. The rising numbers of notifications of CA-MRSA and the resource-intensive nature of the search and destroy program meant that it was unsustainable. The recommendations of the EAG have varied according to the scientific body of knowledge at the time and availability of resources. In particular, the level of direct involvement by PHUs and the CDCD in case follow-up has declined, and the list of CA-MRSA strains that were the targets of enhanced follow-up has changed. Since 2009, GPs who ordered tests that resulted in PVL-positive CA-MRSA isolates received a letter from the Department of Health advising them to decolonise their patient.

Notifications of methicillin-resistant Staphylococcus aureus (MRSA)in Western Australia, 2004 - 2012, by strain grouping (HA=healthcare-associated strains; CA= community-associated strains; PVL=Panton-Valentine leukocidin)

Notifications of methicillin-resistant Staphylococcus aureus (MRSA)in Western Australia, 2004 - 2012

Data source: Typing Laboratory, PathWest Laboratory Medicine and Australian Collaborating Centre for Enterococcus and Staphylococcal Species (ACCESS) Typing and Research

Current situation

Following a review in 2012, and in light of new evidence on the role of PVL1 and the increasing incidence of all CA-MRSA notifications in WA, the EAG recommended that the focus of the program be on all people who acquire CA-MRSA, not just those with PVL-positive strains. In addition, recommendations were made for the management of individuals identified with CA-MRSA strains that were rare in WA but considered to be of particular significance owing to their increased virulence, transmissibility, or pattern of antibiotic resistance.

The key changes to the program are:

  • All CA-MRSA strains will be targeted, not just PVL-positive strains.
  • CDCD staff will cease to be directly involved in the management of individuals with CA-MRSA infections.
  • All individuals identified with a CA-MRSA infection (around 5000 per year) will be sent a letter advising them to attend their primary healthcare provider if they have an active or recurrent infection. It will include an information sheet and explanatory letter for them to take to their healthcare provider.
  • Letters from the Department of Health will no longer be sent directly to the requesting GPs.
  • Decolonisation will now be recommended only when individuals or their household contacts have recurrent CA-MRSA (or staphylococcal-like) infections, are carers or healthcare workers, or are at increased risk for acquiring staphylococcal infection, such as those with chronic skin disorders, diabetes, peripheral vascular disease or immunosupression.
  • The recommended length of decolonisation treatment has been reduced from 10 days to 5 days, and will now include an additional skin antiseptic option.  

Additional recommendations have been made for individuals identified as having rare strains of CA-MRSA that pose a particular risk to public health. Both the individual and the requesting GP will receive an advisory letter. Decolonisation will be required for each of these cases, and screening for clearance is required at week 1 and week 12 post-decolonisation.

These strategies are designed to increase knowledge and awareness of CA-MRSA among consumers and primary healthcare providers to ensure CA-MRSA cases receive the correct management and antibiotic treatment, when required, to minimise the risk of recurrent infections and severe disease.

What the changes mean for GPs

GPs are likely to experience an increase in the number of patients presenting to discuss CA-MRSA infections due to an increase in the number of individuals being sent advisory letters.

Individuals who present with recurrent infections should be decolonised. Complex cases can be referred to a clinical microbiologist or infectious diseases physician via the usual referral pathway for management.

GPs who suspect that skin or soft-tissue infections are occurring in a closely-associated local group, such as a day-care centre, sporting group or dormitory, should inform their local Public Health Unit of a possible CA-MRSA outbreak.

Resources

A range of resources for both consumers and healthcare providers has been developed. It includes information sheets for consumers, guidelines for the medical management of skin and soft-tissue infections, appropriate antibiotic therapy and indications for decolonisation treatment.

For consumer and healthcare provider information visit Western Australia’s Department of Health website and read the Department of Health’s Information Circular on the Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) program in Western Australia.

Reference

  1. Shallcross L, Fragaszy E, Johnson A, Hayward A. The role of the Panton-Valentine leukocidin toxin in staphylococcal disease: a systematic review and meta-analysis. The Lancet, 2013; 13:43–54.

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