MRSA research at Society for Healthcare Epidemiology of America meeting

As promised, a round-up of some of the research presented at the annual meeting of the Society for Healthcare Epidemiology of America (SHEA), held last weekend in San Diego. (Disclosure: I was on the faculty for the meeting; in exchange for co-hosting a session, SHEA will be reimbursing me for airfare and hotel. I wasn't otherwise paid, though.) There were 143 presentations on MRSA; here are a few.

I'm going to put in links to the online abstracts — I have SHEA's permission to do this — but I can't guarantee how long they will stay up. For those outside the science world, what happens at these meetings is that research is presented, in slide/PowerPoint sessions or in a poster, as a preliminary step to getting it published in a journal. Once a journal expresses interest, a cone of silence descends, the researchers are asked not to discuss the research until the paper is printed, and the abstract will probably be taken offline.

So, efforts to control hospital MRSA are showing some success:

• Invasive hospital-onset MRSA infections declined 16% from 2005 to 2007, and hospital-associated community-onset infections went down almost 9% — probably, though not provably, because of in-hospital prevention campaigns. (A. Kallen et al.)
• MRSA control in a small ICU (22 beds) leads to MRSA reductions throughout a 270-bed Montana community hospital. (P.J. Chang et al.)

But those efforts face some complexities:

• Swabbing the nose and culturing the swab, the classic test to check for MRSA colonization, misses 30% of positive patients because they are colonized in the groin or armpit. (C. Crnich et al.)
• If a hospital does not use AST (active surveillance and testing, or "search and destroy") it may seriously underestimate its MRSA incidence, though it may be able to detect general trends. (P.J. Chang et al.)
• But medical centers of similar size and situation that did v. did not use AST achieved similar reductions in hospital infections. (K. Kirkland et al.)
  

Community strains are moving into hospitals:

• Most of the cases of MRSA colonization identified in a Delaware healthcare system were found so soon after admission that they must have begun out in the community and were not due to hospital transmission. (K. Riches et al.)
• The proportion of MRSA bloodstream infections caused by community strains (proven microbioogically) doubled at Chicago's main public hospital between 2000 and 2007. (K. Popovich et al.)
• One out of every 7 ICU cases of MRSA in Atlanta's major public hospital involved a community strain. (H. Blumberg et al.)
• The number of MRSA infections brought to a Chicago-area ER increased 566% between 2002 and 2007, and was seasonally clustered (D. Buchapalli et al.)

And at the same time, hospital strains are moving out into the community:

• Hospital-associated community-onset cases accounted for 58% of all invasive MRSA in the US between 2005 and 2007, with patients undergoing dialysis or those who have been in long-term care the most vulnerable. (J. Duffy et al.)