title: A Comparison of Subtyping Methods for Differentiating Salmonella enterica Serovar Enteritidis Isolates Obtained from Food and Human Sources.
abstract: OBJECTIVE
  To evaluate the abilities of these subtyping methods, we distinguished Salmonella Enteritidis (S. Enteritidis) isolated from food products and human clinical samples between 2009 and 2010 in Seoul using five subtyping methods.
  
  
  METHODS
  We determined the subtypes of 20 S. Enteritidis isolates from food and human sources using phage typing, antimicrobial susceptibility, pulsed-field gel electrophoresis (PFGE), repetitive sequence-based PCR (rep-PCR), and multi-locus sequence typing (MLST).
  
  
  RESULTS
  A total of 20 tested isolates were differentiated into six antimicrobial susceptibility patterns, three different phage types, four different PFGE profiles, seven rep-PCR patterns, and one MLST type. Food isolates were considerably more susceptible to antibiotics than human isolates. We were best able to discriminate among S. Enteritidis isolates using rep-PCR, and obtained the highest Simpson's diversity index of 0.82, whereas other methods produced indices that were less than 0.71. PFGE pattern appeared to be more related to antimicrobial resistance and phage types of S. Enteritidis isolates than rep-PCR. MLST revealed identical alleles in all isolates at all seven loci examined, indicating no resolution.
  
  
  CONCLUSIONS
  The results of this study suggest that rep-PCR provided the best discriminatory power for phenotypically similar S. Enteritidis isolates of food and human origins, whereas the discriminatory ability of MLST may be problematic because of the high sequence conservation of the targeted genes.
authors.affiliation: College of Veterinary Medicine, Konkuk University, Seoul, Korea . ; Division of Vaccine Research, Korea National Institute of Health, Osong, Korea .
authors.forename: Ji-Yeon
authors.initials: JY
authors.lastname: Hyeon
authors.forename: Jung-Whan
authors.initials: JW
authors.lastname: Chon
authors.forename: Jun-Ho
authors.initials: JH
authors.lastname: Park
authors.forename: Moo-Sang
authors.initials: MS
authors.lastname: Kim
authors.forename: Young-Hee
authors.initials: YH
authors.lastname: Oh
authors.forename: In-Soo
authors.initials: IS
authors.lastname: Choi
authors.forename: Kun-Ho
authors.initials: KH
authors.lastname: Seo
keywords: Salmonella enterica serovar Enteritidis; multilocus sequence typing; pulsed-field gel electrophoresis; repetitive sequence-based PCR; subtyping