De effectiviteit van eradicatiebehandeling bij MRSA-dragerschap volgens de vernieuwde SWAB-richtlijn uitgevoerd bij het Centrum infectieziekten Friesland (Izore).

Staphylococcus aureus (S. aureus) is the most seen bacterial cause of skin- and soft tissue-infections. The name is based upon the position of the cocci in bunches of grapes (Greek: staphyle = bunch of grapes, coccos = granule) and the macroscopic gold-yellow colour (Greek: aureus = gold) of the colonies. S. aureus was very successful in gaining resistance against antimicrobial agents. Twenty years after the introduction of antibiotics, S. aureus had already developed resistance against multiple antibiotics, including methicillin (MRSA). Methicillin resistance is caused by a mobile genetic DNA-element, the Staphylococcus Cassette Chromosome (SCCmec), that S. aureus has incorporated in his chromosome. The SCCmec contains the mecA-gen, which produces an altered penicillin-binding protein (PBP) called PBP-2a. PBP’s are involved in the synthesis of the peptidoglycan layer of the bacterial cell wall. Beta-lactam-antibiotics normally attach to PBP’s 1-3 which interrupts with the production of the bacterial cell wall, causing cell death. Beta-lactam-antibiotics cannot bind to PBP-2a, so that the production of the cell wall proceeds and cell death does not occur. MRSA carriage not only means a more difficult way of antibiotic treatment, but also a higher risk of infection; this is also true for healthy people. The epidemiology of MRSA is changing throughout the years. Previously they thought that MRSA was a pure nosocomial pathogen that could only be gained by hospitalized patients (HA-MRSA), but since the eighties there is an increase of MRSA contaminations outside of the hospitals (CA-MRSA). CA-MRSA strains gained new virulence mechanisms that can cause infections to previously healthy individuals. CA-MRSA can be a possible new threat to the population. Despite the high prevalences in the surrounding countries, the prevalence of MRSA in Dutch health institutions is still the lowest of Europe. In 2011 1,8% of the S. aureus-isolates were a MRSA. This low prevalence is for the greater part the result of the search and destroy policy; actively tracing of potential MRSA-carriers, the isolation of suspected or confirmed MRSA carriers and eradication of MRSA-carriage. For the approach of eradication treatment they have developed a guideline (SWAB) ‘treatment of MRSA carriage’ in the Netherlands. The type of treatment depends on the type of carriage: uncomplicated or complicated. The effectiveness of treatment according to the guideline was 60% after one treatment and 80% after multiple treatments. It was also proved that throat carriage should be treated as a complicated carriage. In February 2012 the SWAB-guideline is adjusted to that. We wanted to examine the effectiveness of the guideline after the adjustment. At Izore throat carriage was almost always treated as a complicated carriage. In our study we collected data from 1 January 2005 till 31 January 2011 from the laboratory data system of Izore (Glims). We collected the basis characteristics of the whole MRSA-population and analysed how many patients underwent an eradication treatment and what the outcome was. The results showed a success percentages of 76,8% after one treatment and 88,7% after multiple treatments with a mean number of 1,29 treatments. Young age (P = 0,031), throat carriage (P = 0,005) and skin conditions (P = 0,010) turned out to be the most important factors with a negative influence on the outcome of eradication treatment. Working in the health sector (P = 0,007) was associated with a positive influence on the outcome of eradication treatment. The conclusion of our study is that the adjustment of the SWAB guideline MRSA had led to an increase in effectiveness of eradication treatment of MRSA carriage. Young age, throat carriage, skin conditions and working in the health sector are influencing on the outcome of eradication treatment.