373. Applications of Advanced Genome Mapping in the Military Health System Polytrauma Patient
Session: Poster Abstract Session: Epidemiology - Bacterial Infections
Friday, October 21, 2011
Room: Poster Hall B1
Handouts
  • Waterman 2011 IDSA final.pdf (829.6 kB)
  • Background: 

    Optical genome mapping (OGM) is a novel technique involving the immobilization of DNA molecules on a charged substrate, digestion with a restriction endonuclease,  and assembly into a high-resolution ordered full genome restriction map.  To date, this technology is slow, expensive, and has limited clinical relevance.    One setting where it may be useful is in the polytrauma patient in whom multiple bacterial isolates are often cultured from the same patient. Furthermore, standard of care is to refer subsequent like-appearing positive cultures to the initial culture. This approach can miss important changes in the organism with therapeutic or morbidity and mortality consequences.  

    Methods: 

    Multidrug-resistant Gram-negative bacteria or methicillin-resistant S. aureus  serially isolated from the same patient along multiple hospitalizations in the evacuation chain from Afghanistan to the U.S. (or when there was a concern for breakdown in infection control) underwent  identification and susceptibility testing  followed by pulsed-field electrophoresis (PFGE).  OGM was then performed to see if PFGE missed important differences in strain typing, or if clinically relevant genomic changes were occurring.

    Results: 

    In all infection control settings, OGM strain relatedness was concordant with PFGE.  The time period of serial isolate collection from the same patient ranged from 4 to 50 days.  In settings involving serial isolates, PFGE revealed three predominant clones.   Two patients shared 2 clones, spanning three different hospital locations.  OGM of these isolates did not identify unique differences between the individual isolates of those clones.  However, OGM did identify a large 90kB insertion in a patient with numerous like isolates over a 50 day period, not revealed by PFGE.  The insertion was coincident with a clinically relevant switch in phenotype that occurred in a 24hr period.

    Conclusion: 

    Despite higher cost and resolution, OGM did not provide more actionable information than PFGE for infection control.  OGM revealed potential mechanisms for surprisingly rapid evolution of drug resistance in the same host. If sequencing confirms this finding, the practice of referring serial isolates from the same patient may need to be reconsidered.


    Subject Category: N. Hospital-acquired and surgical infections, infection control, and health outcomes including general public health and health services research

    Paige Waterman, MD1,2, Patrick Mc Gann, PhD1, Matthew Riley, MS1, Adam Briska3, Amy Summers, BS, MT1, Yoon Kwak, MS1 and Emil Lesho, DO1,2, (1)Walter Reed Army Institute of Research, Silver Spring, MD, (2)Uniformed Services University, Bethesda, MD, (3)OpGen, Inc., Madison, WI

    Disclosures:

    P. Waterman, None

    P. Mc Gann, None

    M. Riley, None

    A. Briska, OpGen: Employee, Salary

    A. Summers, None

    Y. Kwak, None

    E. Lesho, None

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