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Published on: January 27, 2021
Pathogenicity of Salmonella enterica subspecies enterica serovar Enteritidis phage type 1 in one-day-old specific
Sadik Ahmad1, Mohamed Hair-Bejo1,2, Elawad A Hussein1
1Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine, Universiti Putra Malaysia, Serdang, Malaysia.
Insights
Salmonella Enteritidis phage type 1 infection in chicks caused reduced body weight and intestinal damage. Bacteria entered the system via the cecal tonsil, leading to systemic infection with low mortality.
Area of Science:
- Veterinary Microbiology
- Avian Pathology
- Bacterial Pathogenesis
Background:
- Limited research exists on Salmonella infection dynamics in newly hatched chicks.
- Understanding Salmonella Enteritidis pathogenicity is crucial for poultry health.
Purpose of the Study:
- To determine the pathogenicity of Salmonella Enteritidis phage type 1 (SE PT1) in one-day-old specific pathogen-free (SPF) chicks.
- To investigate the systemic effects and tissue distribution of SE PT1.
Main Methods:
- Oral inoculation of SPF chicks with SE PT1 (1x10^8 CFU/ml).
- Groups included SE, mortality, and control, with sample collection at multiple time points post-inoculation.
- Bacterial isolation, histological, and ultrastructural examinations were performed.
Main Results:
- Significant decrease in body weight observed from day 2 post-inoculation.
- High SE isolation rates from liver and spleen; significant difference compared to blood and cloacal swabs.
- Intestinal villi height decreased, crypt depth increased, with microvilli erosion and necrosis in the cecal tonsil.
Conclusions:
- SE PT1 causes systemic infection in young chicks, characterized by diarrhea, reduced body weight, and intestinal lesions.
- High bacterial load in the liver and mild organ lesions were noted, with low overall mortality.
- Bacterial entry into the systemic circulation occurs through M-like cells in the cecal tonsil.
Background:
The studies about Salmonella infection in newly hatched chicks were not extensive.
Aim:
The objective of this study was to determine the pathogenicity of Salmonella enterica subspecies enterica serovar Enteritidis (SE) phage type (PT) 1 in one-day-old specific pathogen-free (SPF) chicks.
Methods:
Seventy, one-day-old SPF chicks, were divided into SE group (30 chicks), mortality group (10 chicks), both orally inoculated (1.0 ml) with SE PT1 (1 × 108 colony-forming unit per 1.0 ml), and one control group (30 chicks). The chicks were sacrificed at 6 and 12 hours, and days 1, 2, 3, 5, 7, 10, 14, and 21 post-inoculation (pi). Samples were collected for bacterial isolation, histological examination, and ultrastructural examination.
Results:
Starting from day 2 pi, the body weight in the SE group significantly (p < 0.05) decreased. The SE isolation percentages from the liver, spleen, mid-intestinal content, cecal content, cecal tonsil, blood, and cloacal swab were 0.73, 0.77, 0.33, 0.33, 0.36, 0.40, and 0.30, respectively. The isolation percentage in the liver was significantly (p < 0.05) higher than the blood and cloacal swab. The villi heights and crypt depths in the SE group were significantly (p < 0.05) greater and smaller, respectively. Ultrastructurally, erosion and necrosis were observed in the microvilli of the cecal tonsil. The bacteria were engulfed by macrophages at the interepithelial clefts of the M-like M cells.
Conclusion:
It was concluded that the inoculation of SE PT 1 in one-day-old chicks caused a systemic infection with diarrhea, a decrease in the body weight and villi height in the duodenum, jejunum, and ileum, and high bacterial loading in the liver with mild gross and histological lesions of organs, erosion, and necrosis of microvilli and low mortality. The bacteria entered the body system from the intestinal tract through the interepithelial clefts of the M-like M cells of the cecal tonsil.
