Escherichia coli cluster evaluation.
Gupta et al. interpret their experience as indicating that, with geographically dispersed isolates, a higher degree ofgenomic similarity than is reliably provided by single-enzyme PFGE is necessary to improve specificity, thereby avoiding fruitless investigative efforts (1). However, whether the subclusters shown by their second-round PFGE were more epidemiologically meaningful than the original cluster remains unclear, nor do we know how representative this experience is. Determination of optimal genetic similarity parameters for geographically distributed epidemiologic surveillance (e.g., through PulseNet) would seem to require more in-depth empirical assessment, possibly incorporating Bayesian likelihood (3).
(1.) Gupta A, Hunter SB, Bidol SA, Dietrich S, Kincaid J, Salehi E, et al. Escherichia coli O157 cluster evaluation. Emerg Infect Dis. 2004; 10:1856-8.
(2.) Davis MA, Hancock DD, Better TE, Call DR. Evaluation of pulsed-field gel electrophoresis as a tool for determining the degree of genetic relatedness between strains of Escherichia coli 0157:H7. J Clin Microbiol. 2003;41:1843-9.
(3.) Gardner IA. An epidemiologic critique of current microbial risk assessment practices: the importance of prevalence and test accuracy data. J Food Prot. 2004;67:2000-7.
James R. Johnson *
* University of Minnesota, Minneapolis, Minnesota, USA
Address for correspondence: James R. Johnson, VA Medical Center, Infectious Diseases (111F), Rm 3B-101 1 Veterans Dr, Minneapolis, MN 55417, USA; email: email@example.com
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|Author:||Johnson, James R.|
|Publication:||Emerging Infectious Diseases|
|Article Type:||Letter to the editor|
|Date:||Mar 1, 2007|
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