Facilitated molecular typing of Shigella isolates using ERIC-PCR

To evaluate the performance of enterobacterial repetitive intergenic sequence-based polymerase chain reaction (ERIC-PCR) typing versus the current standard for the typing of Shigella pulsed gel electrophoresis (PFGE), we typed 116 Shigella isolates from a village in an endemic setting over a 20-month period using both methods. PFGE identified 37 pulse types and had a discrimination index of 0.925 (95% confidence interval = 0.830-1.00), whereas ERIC-PCR identified 42 types and had a discrimination index of 0.961 (95% confidence interval = 0.886-1.00). PFGE and ERIC-PCR showed a 90.4% correlation in the designation of isolates as clonal or non-clonal in pairwise comparisons. Both systems were highly reproducible and provided highly similar and supplementary data compared with serotyping regarding the transmission dynamics of shigellosis in this community. ERIC-PCR is considerably more rapid and inexpensive than PFGE and may have a complementary role to PFGE for initial investigations of hypothesized outbreaks in resource-limited settings.