CA-MRSA — not just a US problem

One of the mysteries of MRSA research has been the apparent difference in MRSA prevalence in different countries. Hospital-associated MRSA is a well-understood foe in Europe, but identification of CA-MRSA is infrequent. So is CA-MRSA actually less common in other countries, or is that an artifact produced by less surveillance there or more awareness here?

A new journal sheds some light on the question, and also sounds a warning. A team from University College-London's Centre for Infectious Disease Epidemiology analyzed data that are easily available in the UK because the country has a national healthcare system: "hospital episode statistics" (hospital admissions by primary diagnostic code) from 1989 to 2004. The team chose the codes that would indicate admissions for a variety of community-onset staph-related diseases: septicemia, pneumonia, bone and joint infections, and an array of skin and soft-tissue infections.

What they found: Over those 15 years, admits for staph septicemia, pneumonia and scalded-skin syndrome rose 5-fold; abscesses and cellulitis, 3-fold, and bone and joint infections, 1.5-fold. These were much larger increases than in the only national surveillance system which collects voluntary reports just of Staph bacteremia and showed a 2.5-fold increase from 1990 to 2004.

Because the study is based on ICD-9/ICD-10 codes, it contains no microbiological information. However, the authors point out that the invasive diseases captured by the codes are associated with PVL toxin, which in turn is associated with CA-MRSA more than HA-MRSA or MSSA. They say:

We identified a previously undescribed but major increase in pathogenic community-onset staphylococcal disease over the past 15 years. These trends are of concern given the international emergence of invasive community-onset staphylococcal infections.

The paper has been published ahead of print by Emerging Infectious Diseases. The cite is: Hayward A. et al. Increasing hospitalizations and general practice prescriptions for community-onset staphylococcal disease, England. Emerg Infect Dis. 2008 May; [Epub ahead of print]