%0 Journal Article %A Bingen, E. %A Denamur, E. %A Lambert-Zechovsky, N. %A Braimi, N. %A El Lakany, M. %A Elion, J. %T DNA restriction fragment length polymorphism differentiates recurrence from relapse in treatment failures of Streptococcus pyogenes pharyngitis %D 1992 %J Journal of Medical Microbiology, %V 37 %N 3 %P 162-164 %@ 1473-5644 %R https://doi.org/10.1099/00222615-37-3-162 %I Microbiology Society, %X Summary In the evaluation of treatment failure in Streptococcus pyogenes pharyngitis it is necessary to distinguish between persistence of the original streptococcus and acquisition of a new strain. We used the analysis of restriction fragment length polymorphism (RFLP) of total DNA and of ribosomal DNA (rDNA) regions (ribotypes) as epidemiological tools to compare 43 pre- and post-treatment S. pyogenes strains obtained from 20 patients. In 16 cases pre- and post-treatment strains gave indistinguishable RFLP patterns of total DNA, strongly suggesting relapse with the same strain. However, in four cases different patterns were obtained for the pre- and post-treatment isolates, indicating recurrence due to the acquisition of a new strain. Ribotyping did not improve discrimination among strains. Thus, analysis of DNA RFLP is a promising method for distinguishing recurrence from relapse in failures of pharyngitis treatment. %U https://www.microbiologyresearch.org/content/journal/jmm/10.1099/00222615-37-3-162