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Updated: Feb 23, 2026
Chronic Salmonella Infection Induced Intestinal Fibrosis
Published on: September 22, 2019
Simultaneous oral administration of Salmonella Infantis and S. Typhimurium in chicks
Koichi Murakami1,2, Eriko Maeda-Mitani2, Daisuke Onozuka3
1Infectious Disease Surveillance Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo, 208-0011 Japan.
Insights
Salmonella Infantis and Salmonella Typhimurium showed similar reproductive rates in chicks. However, S. Infantis
Area of Science:
- Veterinary Microbiology
- Food Safety
- Poultry Science
Background:
- Salmonella enterica subspecies enterica serovar (S.) Infantis is a predominant serovar in broiler chickens.
- Previous studies suggest S. Infantis may have higher reproductive rates in chicks compared to other Salmonella serovars.
Purpose of the Study:
- To investigate the hypothesis that S. Infantis possesses higher basic reproductive rates in chicks than other Salmonella serovars.
- To compare the colonization dynamics of S. Infantis and S. Typhimurium in young chickens.
Main Methods:
- One-day-old specific-pathogen-free chicks were challenged orally with S. Infantis and S. Typhimurium.
- Challenged chicks were co-housed with progressively larger groups of non-infected chicks to assess transmission and colonization.
- Salmonella enumeration was performed on bowel and liver samples at 18 days of age.
Main Results:
- Both S. Infantis and S. Typhimurium were isolated from all groups except controls.
- S. Typhimurium showed higher isolation frequency in bowel samples from contact-exposed chicks (Groups B, C, D).
- No significant differences in basic reproductive rates or liver colonization were observed between the two serovars.
Conclusions:
- Contrary to the hypothesis, S. Infantis and S. Typhimurium exhibited similar basic reproductive rates in this study.
- The initial quantitative dominance of S. Infantis in chicken flocks might contribute to its prevalence in broiler chickens, as suggested by previous research.
Background:
To confirm the hypothesis that Salmonella enterica subspecies enterica serovar (S.) Infantis has higher basic reproductive rates in chicks compared with other Salmonella serovars, 1-day-old specific-pathogen-free chicks (n = 8) were challenged simultaneously with S. Infantis and S. Typhimurium per os. Challenged chicks (Group A) were then housed with non-infected chicks (Group B, n = 4) for 6 days (from 2 to 8 days of age). Group B birds were then housed with other non-infected birds (Group C, n = 4), which were then transferred to cages containing a further group of untreated chicks (Group D, n = 2). A control group consisting of four non-infected chicks was used for comparison. All chickens were humanely sacrificed at 18 days of age, and Salmonella from bowel and liver samples were enumerated.
Results:
Both serovars were isolated from all groups except the control group. S. Typhimurium was isolated at a greater frequency than S. Infantis from the bowel samples of chicks from Groups B, C and D, while no differences in colonisation rates were observed between the two serovars in liver samples from Groups B, C and D. S. Typhimurium, but not S. Infantis, was immunohistochemically detected in the lamina propria of the cecum and rectum in five birds of Group A. Despite the competitive administration, neither of the two serovars completely excluded the other, and no differences were observed in basic reproductive rates between the two serovars.
Conclusions:
These findings, together with data from previous studies, suggest that the initial quantitative domination of S. Infantis in chicken flocks may explain why this serovar is predominant in broiler chickens.
