Composition of Gut Microbiota Influences Resistance of Newly Hatched Chickens to Salmonella Enteritidis Infection

Abstract

Since poultry is a very common source of non-typhoid Salmonella for humans, different interventions aimed at decreasing the prevalence of Salmonella in chickens are understood as an effective measure for decreasing the incidence of human salmonellosis. One such intervention is the use of probiotic or competitive exclusion products. In this study we tested whether microbiota from donor hens of different age will equally protect chickens against Salmonella Enteritidis infection. Newly hatched chickens were therefore orally inoculated with cecal extracts from 1-, 3-, 16-, 28-, and 42-week-old donors and 7 days later, the chickens were infected with S. Enteritidis. The experiment was terminated 4 days later. In the second experiment, groups of newly hatched chickens were inoculated with cecal extracts of 35-week-old hens either on day 1 of life followed by S. Enteritidis infection on day 2 or were infected with S. Enteritidis infection on day 1 followed by therapeutic administration of the cecal extract on day 2 or were inoculated on day 1 of life with a mixture of the cecal extract and S. Enteritidis. This experiment was terminated when the chickens were 5 days old. Both Salmonella culture and chicken gene expression confirmed that inoculation of newly hatched chickens with microbiota from 3-week-old or older chickens protected them against S. Enteritidis challenge. On the other hand, microbiota from 1-week-old donors failed to protect chickens against S. Enteritidis challenge. Microbiota from 35-week-old hens protected chickens even 24 h after administration. However, simultaneous or therapeutic microbiota administration failed to protect chickens against S. Enteritidis infection. Gut microbiota can be used as a preventive measure against S. Enteritidis infection but its composition and early administration is critical for its efficacy.

Gut Anaerobes Capable of Chicken Caecum Colonisation

“…All the remaining Gram-positive isolates did not colonise the chicken caecum during the first week of life. The ability of Gram-negative bacteria to colonise corroborates earlier findings that characterised the bacterial species colonising the chicken caecum after administration of caecal extracts [5,6,24] or after contact with an adult hen [25]. The isolates that successfully colonised the caeca of chicks did not require any other microbiota members to co-colonise.…”

“…The rather small effect on other microbiota members can also be seen in their ability to affect S. Enteritidis colonisation. Though some of the isolates decreased S. Enteritidis counts by one log of magnitude, this reduction must be considered as minor because colonisation with complex microbiota reduces Salmonella counts by five logs [5].…”

“…The chicken inflammatory response in the caecum was determined by quantitative reverse transcribed PCR (Qiagen, Hilden, Germany) quantifying the expression of extracellular fatty acid binding protein (ExFABP) as described previously [5]. This gene was selected due to its high basal expression in the caecum of chickens and also high induction following S. Enteritidis challenge [20].…”

“…However, contact between hen and chicks has been interrupted in commercial production, and the intestinal tract of commercially hatched chicks is gradually colonised from environmental sources only [1][2][3][4]. However, if the chicks are provided microbiota from a hen experimentally, they can be colonised by adult-type microbiota from the very first days of life [5,6].…”

Integrative analysis of gut microbiome and metabolites revealed novel mechanisms of intestinal Salmonella carriage in chicken

“…Mature and strong presence of the core gut microbiota community is a key to developing stable functional gastrointestinal tracts with the ability to confer protection against potential pathogen colonization. Transfer of mature and stable gut microbiota from adult chickens to newly hatched chicks also has suggested its effect on improving colonization resistance against SE 7 . To our knowledge, the potential ability of the transitional phase in developing resident gut microbiota of two-week old chicks to confer protection against SE colonization in the gut has not yet been explored.…”