04 April 2008

CA-MRSA increasing in Denmark

Again from the annual meeting of the Society for General Microbiology, a report that CA-MRSA cases are rising in Denmark, a country with a very low incidence rate of HA-MRSA — about 1% of isolates — thanks to aggressive screening of any patient who has been treated abroad as well as any health care worker who has worked outside the country.

But a team from the Statens Serum Institut in Copenhagen says that is now changing as CA-MRSA moves into the country. From an SGM press release:
"We have managed to hold the frequency of MRSA cases down to under one per cent in Denmark for over 30 years. But in 1997 we recognised the first cases of community acquired MRSA, a new strain independent of hospital and nursing home contacts, in a young adult and two families in a rural town", says Professor [Robert] Skov [of Statens]. "From the families we traced the superbug being transmitted through a kindergarten, a school, a factory and a farm. Between 1999 and 2006 the number of community acquired MRSA infections increased from 11 to 175 a year, making up more than 22% of all MRSA infections, as a rising proportion."
As is commonly the case, the paper presented at the SGM is not online. The press release was carried by the site Medical News Today. It contains no details on whether the cases were identified as CA-MRSA by risk factor or by microbiology, and therefore doesn't answer the obvious question of whether they are truly CA-MRSA, or hospital-acquired/community-onset HAIs.

However: A 2005 paper on which Skov was an author did include typing results, and suggests that Denmark now is seeing cases of a new MRSA type, similar (allowing for the vast difference in scale) to what has happened in the US since the 1990s. From the abstract:
Comparison of the 45 community-onset MRSA (CO-MRSA) infections with the 36 hospital-acquired MRSA (HA-MRSA) infections showed several striking contrasts. Most CO-MRSA were recovered from skin and soft tissue infections caused by isolates carrying the Panton-Valentine leucocidin toxin genes, and the majority (84%) of isolates belonged to a single clonal type, ST80-IV, which has been found in the community in other European countries. Clone ST80-IV could be traced in Denmark back to 1993. ST80-IV was rarely found in HA-MRSA infections.
The paper is Faria, NA et al. Epidemiology of Emerging Methicillin-Resistant Staphylococcus aureus (MRSA) in Denmark: A Nationwide Study in a Country with Low Prevalence of MRSA Infection. J Clin Micro April 2005, 43 (4) 1836-1842. The abstract is here.

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