ORSA comes up a lot, specifically how to decolonize patients with community-acquired ORSA (CA-ORSA). The UNC hospital epi people put together a brochure, which is sometimes hard to locate. I found this PDF online, from Kaiser Permanente out in California, which outlines I think what's pretty standard for us around here:
http://www.kplearning.com/10_national_site/uploads/B1S3.pdf
Johns Hopkins used to publish this nice periodic newsletter on HIV issues, but they've discontinued it due to time and budget constraints. Nevertheless, there was a nice article in the September 2004 edition that addressed CA-ORSA:
The only caveat I'd put on this is, please know that the conventional dosing of TMP/SMX (Bactrim™, Septra™) at one DS tablet twice a day (as in the Hopkins thing) is now considered insufficient for ORSA treatment (at least around here, anyway). You need TWO DS tabs twice daily, and make sure you adjust for renal function, if reduced.
In general, we use doxycycline as our second-line agent, followed by clindamycin. Our micro lab will report clindamycin susceptibility separate from erythromycin – but outside labs may not be as reliable. Remember that CA-ORSA may have inducible resistance to the lincosamides (of which clinda is one) that won't show up in microdilution susceptibility testing used in outside hospitals and labs. You can't detect this is unless a "D-test" is performed, with both an e-mycin (15 µg) and a clinda (2 µg) disk dropped onto the plate:
If the bug has inducible resistance, there'll be a flattening of the zone of inhibition between the two disks, suggesting that the bugs closer to the e-mycin disk have switched on their inducible resistance genes and are now laughing at the silliness of you attempting to use clindamycin to kill them.
Editorial note: The acronym "MRSA," for methicillin-resistant Staphylococcus aureus, is a humongo misnomer, since we don't use methicillin for resistance testing, and haven't in many years. Oxacillin is used on the plates, not methicillin – so you may hear it referred to more often in the micro lab as ORSA, and more often in the community as MRSA. If you're an ID purist, go with ORSA and look smart when someone asks what the hell it is that you're saying. (Or look like a big know-it-all dork. :) )
– Christopher Hurt
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