Student Research: Pi-Ching Peggy Yang

MS, , 1998
Faculty Advisor:

Comparison of Molecular Subtyping Methods for E. Coli 0157:H7: Their Utility in Epidemiological Investigations


The objective of this project was to determine the most effective subtyping method or combinaation of subtyping methods for outbreak investigation of the E. coli O157:H7 pathogen. Since the first reported outbreak in 1982, E. coli O157:H7 has emerged as an important pathogen. An estimated 20,000 illnesses and 250 deaths in the United States alone have been attributed to E. coli O157:H7 infections each year. There are a number of genotypic subtyping methods that have been used for interstrain differentiation of this organism. These include macrorestriction fingerprinting with pulsed-field gel electrophoresis (MARF-PFGE) and restriction fragment length polymorphisms using Shiga0like toxin genes (STX-RFLP). Recently, a new method has been developed termed microrestriction fingerprinting (MRF).

Using a set of 215 E. coli O157:H7 isolates from the State of Oregon, the strengths and weaknesses of MARF-PFGE, STX-RFLP, and MRF subtyping procedures were compared with respect to sensitivity, reproducibility and epidemiological relevance of the data. This collection included both sporadic and outbreak associated isolates received by Oregon State Laboratory between 1995 and 1997. Results of this study have shown that MRF had beter correlation with the epidemiological histories of each case than MARF-PFGE or STX-RFLP because of its higher discriminatory power. All three methods were found to have comparable reproducibility when tested with multiple isolates from the same patient.