Salmonella enteritidis in eggs, cloacal swab specimens, and internal organs of experimentally infected White Leghorn chickens

Abstract

Objective - To investigate prevalence of Salmonella enteritides-positive eggs, excretion of the organism in fecal droppings, and infection of internal organs after oral inoculation of White Leghorn hens with S enteritidis phage type 8 Animals - 30 White Leghorn laying hens. Procedure - At 25 weeks of age, hens were each inoculated orally with 1010 colony-forming units of S enteritidis, then were observed for 8 weeks. Results - Salmonella enteritidis Y-8P2 did not cause any clinical signs of disease or decrease in egg production. However, at 1 week after inoculation, 63.9% of the eggs collected from inoculated hens were culture positive for S enteritidis. The organism was isolated from the shell washings, egg shells, yolk, and albumen. A total of 592 eggs from S enteritidis-inoculated hens were examined. Of these eggs, 157 (26.5%) were positive for S enteritidis on external shell washings alone, 17 (2.9%) were positive for S enteritidis internally, and 44 (7 4%) were positive for S enteritidis externally and internally. The percentage of culture-positive eggs gradually decreased between postinoculation weeks 2 and 5, then gradually increased to a high of 76% at week 8. At 3, 7, and 10 days after S enteritidis inoculation, cloacal swab specimens from 3 hens were positive for S enteritidis. Salmonella enteritidis was recovered from ovary, oviduct, liver, and cecal junction from S enteritidis-inoculated hens. Conclusions - Our results indicated that birds infected with this isolate produced S enteritidis-positive eggs at high frequencies initially, that decreased over time. When S enteritidis antibody began to decrease, reaching geometric mean titer ≤ 40, the frequency of S enteritidis-positive eggs increased.