MRSA Screening Pro-Con
In January, I promised that I’d post a link to the slides from the “pro-con” session on MRSA screening programs I did with John Jernigan at the Remington Winter Course last week. You can find them here—scroll to Thursday at 5 pm. To view the slides, you have to select “read-only” when the pop-up screen appears. I have another such session at the NARSA meeting in Reston, Virginia on Monday, this time with Lance. A summary of that session can now be found here.
Two things interested me about John’s arguments last week. First, he put a lot of stock in the Staphylococcus aureus antibiogram as one measure of success in MRSA control. I have always felt the “% MRSA” reported in an antibiogram is a very poor measure of disease burden. Which unit would you rather be admitted to: the one with 10 S. aureus infections per month, 3 of which are due to MRSA (“%MRSA” = 30), or the unit with 1 infection per month that happens to be due to MRSA (“%MRSA = 100)? Secondly, he argued that “in-hospital” MRSA infection rates were not a good measure of a hospital’s success in reducing MRSA transmission. So even if a hospital can eradicate MRSA infections from its ICUs, it still might be serving as an “amplifier” of MRSA carriage if it doesn’t implement active screening and isolation. The resulting infections, presumably, have their onset after discharge. The problem with this line of argument is the lack of data suggesting that active MRSA surveillance in the acute care setting prevents “community-onset, healthcare-associated” MRSA disease.
Two things interested me about John’s arguments last week. First, he put a lot of stock in the Staphylococcus aureus antibiogram as one measure of success in MRSA control. I have always felt the “% MRSA” reported in an antibiogram is a very poor measure of disease burden. Which unit would you rather be admitted to: the one with 10 S. aureus infections per month, 3 of which are due to MRSA (“%MRSA” = 30), or the unit with 1 infection per month that happens to be due to MRSA (“%MRSA = 100)? Secondly, he argued that “in-hospital” MRSA infection rates were not a good measure of a hospital’s success in reducing MRSA transmission. So even if a hospital can eradicate MRSA infections from its ICUs, it still might be serving as an “amplifier” of MRSA carriage if it doesn’t implement active screening and isolation. The resulting infections, presumably, have their onset after discharge. The problem with this line of argument is the lack of data suggesting that active MRSA surveillance in the acute care setting prevents “community-onset, healthcare-associated” MRSA disease.
Both of John Jernigan's arguments seem quite flawed. The antibiogram one makes no sense whatsoever--it's the incidence that's important not the proportion and Dan's example illustrates that. The second argument assumes that successful reduction of MRSA infections in the hospital without using ADI is NOT reducing MRSA colonization. While I am not aware of published data to prove or disprove that assumption, it's highly speculative at best and not at all congruent with our understanding of the epidemiology of this pathogen.
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