Research article

Rapid screening of Salmonella enterica serovars Enteritidis, Hadar, Heidelberg and Typhimurium using a serologically-correlative allelotyping PCR targeting the O and H antigen alleles

Yang Hong^1,2 , Tongrui Liu^1,6 , Margie D Lee^1,4 , Charles L Hofacre^1,4 , Marie Maier^1,6 , David G White⁵ , Sherry Ayers⁵ , Lihua Wang³ , Roy Berghaus¹ and John J Maurer^1,4

¹Department of Population Health, The University of Georgia, Athens, GA 30602, USA

²Department of Infectious Diseases, The University of Georgia, Athens, GA, USA

³Department of Statistics, The University of Georgia, Athens, GA 30602, USA

⁴Center for Food Safety and Quality Enhancement, The University of Georgia, Griffin, GA 30223, USA

⁵Center for Veterinary Medicine, U.S. Food and Drug Administration, Laurel, MD 20708, USA

⁶USDA ARS, Russell Research Center, 950 College Station road, Athens, GA 30605. T. Liu- Emory University, 1701 Uppergate Drive, Atlanta, GA 30322, USA

author email corresponding author email

BMC Microbiology 2008, 8:178doi:10.1186/1471-2180-8-178

Published:	9 October 2008

Abstract

Background

Classical Salmonella serotyping is an expensive and time consuming process that requires implementing a battery of O and H antisera to detect 2,541 different Salmonella enterica serovars. For these reasons, we developed a rapid multiplex polymerase chain reaction (PCR)-based typing scheme to screen for the prevalent S. enterica serovars Enteritidis, Hadar, Heidelberg, and Typhimurium.

Results

By analyzing the nucleotide sequences of the genes for O-antigen biosynthesis including wba operon and the central variable regions of the H1 and H2 flagellin genes in Salmonella, designated PCR primers for four multiplex PCR reactions were used to detect and differentiate Salmonella serogroups A/D1, B, C1, C2, or E1; H1 antigen types i, g, m, r or z₁₀; and H2 antigen complexes, I: 1,2; 1,5; 1,6; 1,7 or II: e,n,x; e,n,z₁₅. Through the detection of these antigen gene allele combinations, we were able to distinguish among S. enterica serovars Enteritidis, Hadar, Heidelberg, and Typhimurium. The assays were useful in identifying Salmonella with O and H antigen gene alleles representing 43 distinct serovars. While the H2 multiplex could discriminate between unrelated H2 antigens, the PCR could not discern differences within the antigen complexes, 1,2; 1,5; 1,6; 1,7 or e,n,x; e,n,z₁₅, requiring a final confirmatory PCR test in the final serovar reporting of S. enterica.

Conclusion

Multiplex PCR assays for detecting specific O and H antigen gene alleles can be a rapid and cost-effective alternative approach to classical serotyping for presumptive identification of S. enterica serovars Enteritidis, Hadar, Heidelberg, and Typhimurium.