Undefined and Defined Bacterial Preparations for the Competitive Exclusion of Salmonella in Poultry - A Review

Abstract

During the past two decades, there have been many studies on the efficacy of competitive exclusion for the control of Salmonella in poultry. Undefined preparations of cultured fecal or cecal microflora generally reduce the prevalence of infected chicks upon challenge with a standard dose of Salmonella under laboratory conditions; in contrast, results under field conditions are more variable. The protective capacity of undefined cultures can be affected by several factors including the source of microflora, method for protective culture administration, presence of poultry feed additives, in-laboratory or natural environmental challenge, and hygienic practices on the farm. The formulation of effective defined cultures is most difficult because of insufficient knowledge on the underlying protective mechanism(s) and interactions between gut microflora. Defined cultures are less effective than undefined cultures under laboratory conditions and afford little protection against natural Salmonella challenge; their potency decreases upon storage and manipulation of single or mixtures of defined culture isolates.

Exposure of different bacterial inocula to newborn chicken affects gut microbiota development and ileum gene expression

“…To prevent pathogenic bacteria such as Salmonella and Campylobacter from colonizing, commercial competitive-exclusion products have been developed for the neonatal animals (Pivnick and Nurmi, 1982;Schneitz, 2005). These products are composed of a complex of microbial species rather than a simple mixture of a few species (Stavric and D'Aoust, 1993), and made as an undefined bacterial culture by a chemostat system in which a single cecum of the chicken was used as the source of the inoculation (Revolledo et al, 2003;Schneitz, 2005). The compositions of bacterial species in these products are not constant because of the various compositions of the cecal microbiota, and thus inconsistent efficacy has been reported Schneitz, 2005).…”

16S rRNA-Based Analysis of Microbiota from the Cecum of Broiler Chickens

“…Beginning with the studies by Nurmi and Rantala (31), practical means were developed to promote the establishment of mature intestinal microbiota in newly hatched chicks to prevent Salmonella enterica infection. Over the years, numerous preparations of bacteria were administered to young chicks and tested for their efficacy in preventing Salmonella infection (2,14,37,43,44). The consensus derived from these studies was that complex mixtures of bacteria derived from adult chickens rather than single bacterial isolates provided the best protection against Salmonella infection.…”

Use of probiotics for sustainable shrimp culture in Southeast Asia

“…Their mechanisms of action range from the production of antibacterial substances like organic acids, which lower the pH, to the production of hydrogen peroxide, which can be toxic to pathogens (Mohammed 1995) and metabolites, which can neutralize the toxins released by pathogens (Stavric and D'aoust 1993). Probiotics also play a major role in the production of enzymes that increases the utilization of feeds (Stavric and D'aoust 1993) and improves digestion by colonizing the gut of the cultured organism (GESAMP 1997).…”

“…Probiotics also play a major role in the production of enzymes that increases the utilization of feeds (Stavric and D'aoust 1993) and improves digestion by colonizing the gut of the cultured organism (GESAMP 1997). They also produce substances that aid in the detoxification of injurious metabolites (Stavric and D'aoust 1993 In 1997, the United Nations Development Programme (UNDP) funded a study to improve and sustain shrimp production. A team was tasked to study the existing shrimp culture techniques and modify these techniques to sustain production without degrading the environment.…”