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Updated: May 17, 2026
A 1.5 Hour Procedure for Identification of Enterococcus Species Directly from Blood Cultures
Published on: February 10, 2011
Temporal changes in pulsed-field gel electrophoresis banding in vancomycin-resistant Enterococcus faecium and
Milena McLaughlin1, Michael Malczynski, Chao Qi
1Department of Pharmacy Practice, Chicago College of Pharmacy at Midwestern University, Downers Grove, IL 60515, USA.
Background:
Patients are often screened with surveillance cultures to discern transmissions vs transformation of an isolate to vancomycin-resistant Enterococcus faecium. To determine the amount of time between which isolates could be considered genetically similar by pulsed-field gel electrophoresis, isolate change over time within single patients was studied.
Methods:
A minimum of 4 isolates per patient, separated by at least 2 months, were collected from previously frozen stores. Visual comparison of banding patterns was conducted, and percent relatedness was calculated.
Results:
Twenty-eight isolates from 6 patients were studied. No isolate differed by more than 3 bands before 150 days, and the average percent difference per band was 3.7%. The isolates diverged genetically as a linear function of number of bands over time (good model fit intrapatient r(2) = 0.42; poor model fit interpatient r(2) = 0.0062).
Conclusion:
Trajectory of genetic variation appears to be isolate/patient specific; however, commonalities exist and tested isolates were relatively stable out to 150 days.
