Final report from ICAAC-IDSA 08 (news from ICAAC, 3)

The ICAAC-IDSA (48th Interscience Conference on Antimicrobial Agents and Chemotherapy and 46th annual meeting of the Infectious Diseases Society of America) meeting ended a week ago, and I'm still thrashing my way through the thousands of abstracts.

Here's my final, highly unscientific selection of papers that caught my eye:

* Evidence that the community-strain clone USA300 is a formidable pathogen: It first appeared in the San Francisco jail in 2001. By last year, it had become the sole MRSA strain found in the jail — it crowded out all others. (P. Tattevin, abstract C2-225)
* Another paper from the same UCSF research group finds that the emergence of USA300 has caused a dramatic increase in bloodstream infections, most of which are diagnosed in the ER, not after patients are admitted to the hospital. (B. Diep, abstract C2-226)
* And the CDC finds that USA300 is picking up additional resistance factors, to clindamycin, tetracycline and mupirocin, the active ingredient in the decolonization ointment Bactroban. (L. McDougal, abstract C1-166)
* An example of the complexity of "search and destroy," the active surveillance and testing program that seeks to identify colonized patients before they transmit the bug to others in a health care institution: Patients spread the bug within hours, often before test results judging them positive have been returned from the lab. (S. Chang, abstract K-3379b)
* In addition to the report from Spain I posted on during the meeting, there is a report of emerging linezolid resistance in France. (F. Doucet-Populaire, abstract C1-188)
* And in addition to the abundant new news about MRSA in pork, and "pork-MRSA" or ST 398, in humans, over the past few days, there were reports of MRSA in milk in Brazil (W. Gebreyes, abstract C2-1829) and Turkey (S. Turkyilmaz, abstract C2-1832), and beef and chicken in Korea (YJ Kim, abstract C2-1831), as well as ST 398 itself acquiring resistance to additional drugs. (Kehrenberg, abstract C1-171)
* Echoing many earlier findings that MRSA seems most common among the poor, the poorly housed and the incarcerated, BR Makos of the University of Texas found that children are more likely to be diagnosed with the bug if they are indigent, or from the South (which I imagine is a proxy for lower socio-economic status, since the South is a more rural, more poor region). (abstract G2-1314)
* And finally, to the long list of objects (ER curtains, stethoscopes) that harbor MRSA, here are more: The ultrasound probes in emergency rooms (B. Wessman, abstract K-3377). Also: Dentures. (Ick.) (D. Ready, abstract K-3354)

7-fold increase CA-MRSA in parts of Chicago

Via the Archives of Internal Medicine, a new study from Cook County Hospital and Rush University Medical Center in Chicago. Betwen 2000 and 2005, the incidence of CA-MRSA at the hospital and its neighborhood clinics increased 6.84 times. Notably, meth-sensitive staph (MSSA) did not decrease - this was a true addition, not a substitution of one strain for another. And 79% of the strains identified were USA300. Important clues to the rapid spread of the bug: Those infected were more likely to have been incarcerated more than once (carrying the bug from the known epicenters of jails and prisons back out into the community) or to live in public housing (possibly because of overcrowding as Chicago demolishes its old-style projects and moves the people who live there into its remaining public housing). The paper raises but can't answer the question of a synergy between those factors: People coming out of jail may be returning to households in public housing creating a bridge between a known epicenter and a population whose living conditions put them at greater risk.

Find the paper here.