Use of multiple-locus variable number tandem repeat analysis and phage typing for subtyping of Salmonella Enteritidis from sporadic human cases in the United States.
OBJECTIVE
To investigate the genetic diversity among S. Enteritidis isolates from different geographic regions to evaluate the relationship between phage types (PTs) and variable number tandem repeat analysis (VNTR) loci.


RESULTS
We performed multiple-locus variable number tandem repeat analysis (MLVA) and phage typing on 245 S. Enteritidis isolates collected from sporadic human clinical cases in Michigan, Minnesota, New York, and Washington states between 2000 and 2007. Ninety-four MLVA types and 22 different PTs were identified. Specific PTs were associated with a predominant allele for certain VNTR loci. Cluster analysis using a minimum-spanning tree demonstrated two major clusters (I, II) and one minor cluster of isolates. PTs 8, 13a, 13 and 34 were significantly associated with MLVA cluster I. Phage types 1, 4, 6a, and 18 were significantly associated with MLVA cluster II.


CONCLUSIONS
We found significant association between MLVA-based clusters and PTs. Certain VNTR loci were associated with specific PTs and could serve as useful molecular markers for S. Enteritidis in epidemiological investigations.


CONCLUSIONS
MLVA genotyping in combination with phage typing can be used for effective characterization of S. Enteritidis isolates. It can also be useful for tracing possible sources during investigations of sporadic and outbreak cases of S. Enteritidis.
Cho
S
S
 National Food Safety and Toxicology Center, Michigan State University, East Lansing, MI, USA.
Whittam
T S
TS
 National Food Safety and Toxicology Center, Michigan State University, East Lansing, MI, USA.
Boxrud
D J
DJ
 Minnesota Department of Health, St. Paul, MN, USA.
Bartkus
J M
JM
 Minnesota Department of Health, St. Paul, MN, USA.
Rankin
S C
SC
 University of Pennsylvania, Philadelphia, PA, USA.
Wilkins
M J
MJ
 Michigan Department of Community Health, Lansing, MI, USA.
Somsel
P
P
 Michigan Department of Community Health, Lansing, MI, USA.
Downes
F P
FP
 Michigan Department of Community Health, Lansing, MI, USA.
Musser
K A
KA
 New York State Department of Health, Albany, NY, USA.
Root
T P
TP
 New York State Department of Health, Albany, NY, USA.
Warnick
L D
LD
 Cornell University, Ithaca, NY, USA.
Wiedmann
M
M
 Cornell University, Ithaca, NY, USA.
Saeed
A M
AM
 National Food Safety and Toxicology Center, Michigan State University, East Lansing, MI, USA.
D000293:Adolescent; D000328:Adult; D000483:Alleles; D001434:Bacteriophage Typing / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D005843:Geography; D006801:Humans; D008297:Male; D008875:Middle Aged; D018598:Minisatellite Repeats; D058885:Multilocus Sequence Typing / Q000379:methods*; D012477:Salmonella enteritidis / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D014481:United States; D055815:Young Adult