12 June 2007

Yes, it is everywhere

Via the journal Emerging Infectious Diseases, a report from a multi-country European team that surveyed CA-MRSA isolates from around the world to determine their ability to produce Panton-Valentine leukocidin, the potent toxin blamed for CA-MRSA's unique ability to cause eruptions on healthy-appearing skin.

Deep-seated infections due to PVL-positive S. aureus can be extremely severe. For example, necrotizing pneumonia carries a mortality rate close to 75%.

Research published in 2003 found that some clones of CA-MRSA were "continent-specific," confined to some extent to particular locations or countries. That appears no longer to be the case.

The ST1 clone USA400 is now detected in Europe and Asia. Some PVL-positive clones, such as ST1 and ST30, can now be considered pandemic, as they are detected in America, Europe, and Asia. Second, on a given continent, PVL-positive CA-MRSA have spread from country to country. For instance, in Europe, PVL-positive CA-MRSA were recently detected in Slovenia, Romania, and Croatia. Third, new PVL-positive CA-MRSA clones are emerging in strains with different genetic backgrounds. While most of the clones described in 2003 by Vandenesch et al. (4) had an agr3 background, the newly described clones are agr1 or agr2. Fourth, PVL-positive CA-MRSA, which were initially susceptible to most antistaphylococcal antimicrobial agents, have acquired new antimicrobial resistance determinants, to gentamicin and ofloxacin, for instance.
The isolates were gathered between 1999 and 2005 and sent to the French National Reference Center for Staphylococci, where the work for this paper was conducted. Yes, 2005. That gap between the obtaining of the isolates adn this analysis underlines one more time the critical need for comprehensive national and global suveillance to track MRSA's movement and evolution. If we don't know where it is, or how it is changing, how can we begin to talk about control?

Link to the full-text paper here.