Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 8, 2000
Publication Date: November 1, 2000
Citation: Seo, K., Holt, P.S., Gast, R.K., Hofacre, C.L. 2000. Elimination of early salmonella enteritidis infection after treatment with competitive-exclusion culture and enrofloxacin in experimentally infected chicks. Poultry Science. Interpretive Summary: Chicks within a couple of days post-hatch are highly susceptible to SE infection and many birds infected at this time remain persistently infected until egg production. Different therapeutic agents such as antibiotics and normal avian gut flora (NAGF), obtained from a preparation of chicken intestinal microflora or defined mixtures of adult chicken gut bacteria, have shown efficacy in reducing Salmonella infection in broilers and layers. Studies were conducted which examined the use of antibiotic therapy in conjunction with normal avian gut flora to reduce the early infection of SE in young chicks. Levels of SE in the intestine were decreased 100 to 10,000-fold in birds treated with NAGF prior to infection. Treatment of birds with antibiotic-NAGF 6-8 weeks after infection reduced the percentage of birds culture positive in the intestine by 30-80%. These results indicate that treatment of day-old chicks with NAGF promote the exclusion of SE from normal gut environment and the combined treatment of SE-positiv young birds with antibiotic and NAGF can substantially reduce early SE- infection of layers. The use of enrofloxacin followed by NAGF could aid the elimination of SE from young chicks persistently infected at an early age and would be a possible alternative to slaughtering the infected flock before egg production
Technical Abstract: The effect of normal avian gut flora (NAGF) and enrofloxacin administration on the early infection of Salmonella enteritidis in young chicks was determined using day old white leghorn chicks. Chicks were divided into two groups, untreated control and NAGF-treated, and then infected with one million CFU of Salmonella enteritidis (SE) per chick by oral gavage. The untreated-infected chicks were further divided into two groups and either were left untreated or medicated with a regimen 10mg/kg of enrofloxacin in drinking water daily for 10 days followed by 2 doses of NAGF beginning at 10 wk and 8 wk age in Trial 1 and Trial 2, respectively. Compared to the untreated group, the cecal colonization of SE was significantly (P<0.05) decreased in NAGF-treated group in Trial 1 and Trial 2. No significant differences in organ infection were observed in the NAGF-treated vs. untreated birds. Although a significant effect of the combined treatment of fenrofloxacin and NAGF on the early infection was not shown in Trial 1 when compared to enrofloxacin only or the untreated group, a significant reduction (P<0.05) in the number of infected chickens or in the number of SE in the cecal contents was observed at 10 wk age in Trial 2. The plasma and intestinal immunological responses were not significant at the early age of the birds. The use of enrofloxacin followed by NAGF could aid the elimination of SE from young chicks persistently infected at an early age.