Multiple drug-resistant organisms (MDRO), pandrug-resistant (PDR) and extensively drug-resistant (XDR) are being defined by a global work group of infectious disease experts, professional society representatives, CDC and European CDC members. It will be vetted to everyone in publications for world-wide comment. As it currently stands MDR would be applied to microorganisms resistant to a minimum of 3 classes of antimicrobial agents. XDR is clearly defined for TB but for non-TB bacteria, XDR would be resistant to almost all approved agents but would remain susceptible to one or two classes. PDR would mean resistance to all available and approved antimicrobial agents. If a Pseudomonas is resistant to all antibiotics within the classes 1) pseudomonal penicillins, 2) pseudomonal cephalosporins and the 3) the aminoglycosides that would be MDR. If also resistant to the carbapenems (imipenem etc) and fluoroquinolones (cipro etc) leaving only the polymyxins, then that would be XDR. If resistant to all approved drugs then = PDR.
I would like to hear comments from Div C to carry back to this work group. As the only microbiologist on the committee, I value your broad views and input. This document will be open for general comments once it is approved and released. This email is only a preview.
Roberta B. Carey, Ph.D.
Chief, Clinical and Environmental Microbiology Branch
Division of Healthcare Quality Promotion
1600 Clifton Road, MS C-16
Atlanta, GA 30333