Which segments of the gastrointestinal tract does Salmonella enteritidis penetrate?

Incidence of Salmonella enteritidis infection is common in hospitals for children, the elderly, and immuno-suppressed individuals. A paper in the December 28, 2007 of the World Journal of Gastroenterology (volume 5, issue 48) is notable because of its potential significance for Salmonella enteritidis therapy in the future.

Salmonella enteritidis can be transmitted to humans through the food production chain. In China, the consumption of poultry products is very high. However, Salmonella enteritidis in the poultry industry has risen dramatically in recent years. As a result of its increased prevalence and its complex life cycle, identifying the regular distribution pattern of Salmonella enteritidis in the gastrointestinal tract will help us to understand its mechanism of action. To discover the port of entry, Dr. Cheng et al (Sichuan Agricultural University, China) used a serovar specific real time PCR for the detection and quantification of Salmonella enteritidis in the gastrointestinal tract of mice.

Based on their results, the jejunum and ileum were positive at 8 h post inoculation and the DNA copies number of Salmonella enteritidis being 10 - 10,000 times more than those in other regions over a 9 d period. One conclusion reported by the investigators is that the jejunum and ileum are the primary sites for Salmonella enteritidis penetration after oral challenge, and these sites are responsible for the organism reaching the heart, liver and spleen.

The reservoir for Salmonella enteritidis is mainly poultry, often adopting asymptomatic infection, and Salmonella enteritidis colonization in the gastrointestinal tract can persist for as long as 18 wk PI in hens. Dr. Cheng et al also found Salmonella enteritidis can present up to 9 d post inoculation in the jejunum, ileum and cecum, without causing apparent symptoms. Does this mean Salmonella enteritidis sets itself up as a commensal over a long time in humans too? This finding is of great significance for future studies; and this paper may increase the evidence that Salmonella enteritidis is a kind of opportunistic pathogen in humans.

Finally, rapid identification of Salmonella enteritidis based on a specific real-time PCR amplifying species specific DNA sequence is a wonderful tool for clinical diagnosis. We believe this study will aid understanding of the mechanisms of action of Salmonella enteritidis infection in vivo, and encourage new studies on how to produce medicines to prevent and treat Salmonella enteritidis infection.

6.1 Reference: Deng SX, Cheng AC, Wang MS, Cao P. Gastrointestinal tract distribution of Salmonella enteritidis in orally infected mice with a species-specific fluorescent quantitative polymerase chain reaction. World J Gastroenterol 2007; 13(48): 6568-6574
http://www.wjgnet.com/1007-9327/13/6568.asp

6.2 Correspondence to: Professor An-Chun Cheng, Avian Diseases Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Yaan 625014, Sichuan Province, China. chenganchun@vip.163.com
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