Message from Matthew J. Arduino of the CDC:

Reports of methicillin-resistant Staphylococcus aureus (MRSA) strains with
intermediate susceptibility to vancomycin (VISA; minimum inhibitory concentration [MIC] = 8mg/ml) have increased recently. All 4 VISAs isolated in the United States were from patients undergoing dialysis (either peritoneal or hemo). It is important to note that not all antimicrobial susceptibility testing methods used in clinical microbiology laboratories detect VISA isolates. Disk diffusion, for example, is ineffective for detecting VISA. In 1998, the Hospital Infections Program (HIP), Centers for Disease Control and Prevention (CDC) developed a sentinel network (SEARCH) to provide a service of confirmatory diagnostics and expedited susceptibility testing for Staphylococcus aureus with reduced susceptibility to vancomycin (MIC * 4mg/ml). This service is meant to aid laboratorians
with the identification of pathogens that may be difficult to detect.

In summary:
* Isolates of S. aureus with vancomycin MICs * 4mg/ml should be retested locally by broth microdilution or Etest methods and may be sent to CDC for confirmatory testing.
* Information on sending isolates to the CDC may be obtained by sending an email to mailto:SEARCH@cdc.gov with your name, title, phone number, and fax number or by calling Jeff Hageman at 404-639-4951.

* All U.S. healthcare organizations and practitioners are encouraged to report such isolates to the State Health Departments and CDC.
* Patients with isolates of S. aureus confirmed at the CDC with a vancomycin MIC * 4mg/ml are eligible for enrollment into nationwide epidemiologic study.

Matthew J. Arduino, Dr.P.H., R.M. (A.A.M.)
Hospital Infections Program
Centers for Disease Control and Prevention
1600 Clifton Road, MS C16
Atlanta, GA 30333

Phone: (404) 639-2318 (office)
(404) 639-2315 (lab)
Fax: (404) 639-3241
Email: mailto:mja4@cdc.gov
http://www.cdc.gov/ncidod/hip



[This message has been edited by Gary Peterson (edited 09-23-1999).]

Dr Aurdino,
I am the microbiology supervisor in a dialysis laboratory. We perform disk diffusion susceptibility testing, when applicable, except for Staph vs Vancomycin. We have been using Etest and reporting the MIC. We do not speciate the coagulase negative organisms. Are we wasting time and money by doing Etest on all Staphs?

Marsha,

It depends on the clinical relevance of the isolates. It may be of some advantage to identify coagulase negative staph. In one, blood cultures study we found that there may be several species present in a positve blood culture. We are currently interested in only Staphylococcus aureus isolates. I would suggest you talk to our Staphyloccus reference laboratory or to the the contacts for the VISA study.

i am seeing more pt. with MRSA in blood and at exit site of subclavian. What is the recommendation regarding isolation for these pts? Have contagious/trasmittable is it.
We do not have a seperate room that is available as we have hep b pt in our only room. ANy suggetion/references to look at woruld be helpfu.