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Clinical and Diagnostic Laboratory Immunology, July 1998, p. 550-555, Vol. 5, No. 4
Diagnostic
Laboratory,1
Department of Microbiology,
Received 15 October 1997/Returned for modification 20 November
1997/Accepted 12 May 1998
Many regulatory and diagnostic programs for the detection of
Salmonella enterica serotype Enteritidis infection in
commercial poultry flocks have relied on rapid Pullorum agglutination
tests to screen birds because of the shared antigens of S. enterica Enteritidis and S. enterica Pullorum and
Gallinarum; however, the use of the enzyme-linked immunosorbent assay
(ELISA) format affords better analytical sensitivity than crude
agglutination tests. In this study, we adapted our earlier conventional
indirect ELISA, using gm flagellin as the antigen, to a kinetics-based, computer-controlled ELISA (KELA). The KELA was used to screen for
flagellin antibody from three commercial flocks: (i) a large flock
involved in a U.S. Department of Agriculture trace back from a human
S. enterica Enteritidis foodborne outbreak
(n = 3,209), (ii) a flock infected with the endemic
S. enterica Enteritidis serotype but which also had
multiple other salmonella serotypes (n = 65), and
(iii) an S. enterica Pullorum-infected flock
(n = 12). The first flock (S. enterica
Enteritidis prevalence of 2.45% based on culture) provided a field
test of the KELA and allowed the calculation of diagnostic sensitivity
(D-Sn) and diagnostic specificity (D-Sp). With a cutoff of 10 (used for
screening flocks [i.e., high sensitivity]), the KELA has a D-Sn of
95.2% and a D-Sp of 18.5%; with a cutoff of 140 (used in confirmatory
flock testing [i.e., high specificity]), the KELA has a D-Sn of
28.0% and a D-Sp of 99.1%. We found that with a cutoff of 60 (D-Sn = 63.1%; D-Sp = 91.6%), we could eliminate reactions
in the KELA caused by other non-S. enterica Enteritidis
salmonellae. The KELA was also compared to two commercial rapid
Pullorum tests, the Solvay (D-Sn = 94.9%; D-Sp = 55.5%) and
the Vineland (D-Sn = 62.0%; D-Sp = 75.3%).
1071-412X/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Interpretations of Antibody Responses to
Salmonella enterica Serotype Enteritidis gm Flagellin in
Poultry Flocks Are Enhanced by a Kinetics-Based Enzyme-Linked
Immunosorbent Assay


*
Corresponding author. Mailing address: Diagnostic
Laboratory, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853. Phone: (607) 253-3900. Fax: (607) 253-3943. E-mail: plm2{at}cornell.edu.
Present address: The Gluck Equine Research Center, Department of
Veterinary Science, University of Kentucky, Lexington, KY 40546.
Present address: College of Veterinary Medicine, Mississippi State
University, Mississippi State, MS 39757.
§
Present address: PA Poultry Federation, Harrisburg, PA 17109.
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