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World J Gastroenterol. Dec 28, 2007; 13(48): 6568-6574
Published online Dec 28, 2007. doi: 10.3748/wjg.v13.i48.6568
Gastrointestinal tract distribution of Salmonella enteritidis in orally infected mice with a species-specific fluorescent quantitative polymerase chain reaction
Shu-Xuan Deng, An-Chun Cheng, Ming-Shu Wang, Ping Cao
Shu-Xuan Deng, Ping Cao, Research Center of Poultry Diseases, College of Animal Science and Veterinary Medicine, Sichuan Agricultural University, Yaan 625014, Sichuan Province, China
An-Chun Cheng, Ming-Shu Wang, Research Center of Poultry Diseases, College of Animal Science and Veterinary Medicine, Sichuan Agricultural University; Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Yaan 625014, Sichuan Province, China
Supported by The National Key Technology R&D Program of China, No. 2004B A901A03; Program for Chang Jiang Scholars and Innovative Research Team in University, No. IRTO753; Program for New Century Excellent Talents in University, No. NCET-04-0906; Sichuan Province Basic Research Program, No. 04JY0290061 and Program for Key Disciplines Construction of Sichuan Province, No. SZD0418
Correspondence to: An-Chun Cheng, Professor, Research Center of Poultry Diseases, College of Animal Science and Veterinary Medicine, Sichuan Agricultural University, Yaan 625014, Sichuan Province, China. chenganchun@vip.163.com
Telephone: +86-835-2885774 Fax: +86-835-2885774
Received: June 27, 2007
Revised: July 14, 2007
Accepted: August 26, 2007
Published online: December 28, 2007
Abstract

AIM: To identify and understand the regular distribution pattern and primary penetration site for Salmonella enteritidis (S. enteritidis) in the gastrointestinal tract.

METHODS: Based on the species-specific DNA sequence of S. enteritidis from GenBank, a species-specific real-time, fluorescence-based quantitative polymerase chain reaction (FQ-PCR) was developed for the detection of S. enteritidis. We used this assay to detect genomic DNA of S. enteritidis in the gastrointestinal tract, including duodenum, jejunum, ileum, cecum, colon, rectum, esophagus and stomach, from mice after oral infection.

RESULTS: S. enteritidis was consistently detected in all segments of the gastrointestinal tract. The jejunum and ileum were positive at 8 h post inoculation, and the final organ to show a positive result was the stomach at 18 h post inoculation. The copy number of S. enteritidis DNA in each tissue reached a peak at 24-36 h post inoculation, with the jejunum, ileum and cecum containing high concentrations of S. enteritidis, whereas the duodenum, colon, rectum, stomach and esophagus had low concentrations. S. enteritidis began to decrease and vanished at 2 d post inoculation, but it was still present up to 5 d post inoculation in the jejunum, ileum and cecum, without causing apparent symptoms. By 5 d post inoculation, the cecum had significantly higher numbers of S. enteritidis than any of the other areas (P < 0.01), and this appeared to reflect its function as a repository for S. enteritidis.

CONCLUSION: The results provided significant data for clarifying the pathogenic mechanism of S. enteritidis in the gastrointestinal tract, and showed that the jejunum, ileum and cecum are the primary sites of invasion in normal mice after oral infection. This study will help to further understanding of the mechanisms of action of S. enteritidis.

Keywords: Fluorescence-based quantitative polymerase chain reaction; Gastrointestinal tract; Salmonella enteritidis