Chicken Caecal Microbiome Modifications Induced by Campylobacter jejuni Colonization and by a Non-Antibiotic Feed Additive

Abstract

Campylobacter jejuni is an important zoonotic foodborne pathogen causing acute gastroenteritis in humans. Chickens are often colonized at very high numbers by C. jejuni, up to 109 CFU per gram of caecal content, with no detrimental effects on their health. Farm control strategies are being developed to lower the C. jejuni contamination of chicken food products in an effort to reduce human campylobacteriosis incidence. It is believed that intestinal microbiome composition may affect gut colonization by such undesirable bacteria but, although the chicken microbiome is being increasingly characterized, information is lacking on the factors affecting its modulation, especially by foodborne pathogens. This study monitored the effects of C. jejuni chicken caecal colonization on the chicken microbiome in healthy chickens. It also evaluated the capacity of a feed additive to affect caecal bacterial populations and to lower C. jejuni colonization. From day-0, chickens received or not a microencapsulated feed additive and were inoculated or not with C. jejuni at 14 days of age. Fresh caecal content was harvested at 35 days of age. The caecal microbiome was characterized by real time quantitative PCR and Ion Torrent sequencing. We observed that the feed additive lowered C. jejuni caecal count by 0.7 log (p<0.05). Alpha-diversity of the caecal microbiome was not affected by C. jejuni colonization or by the feed additive. C. jejuni colonization modified the caecal beta-diversity while the feed additive did not. We observed that C. jejuni colonization was associated with an increase of Bifidobacterium and affected Clostridia and Mollicutes relative abundances. The feed additive was associated with a lower Streptococcus relative abundance. The caecal microbiome remained relatively unchanged despite high C. jejuni colonization. The feed additive was efficient in lowering C. jejuni colonization while not disturbing the caecal microbiome.

Age-Related Differences in the Luminal and Mucosa-Associated Gut Microbiome of Broiler Chickens and Shifts Associated with Campylobacter jejuni Infection

“…According to Pan and Yu (2014) alterations in one phyla or species may not only affect the host directly, but can also disrupt the entire microbial community. Notably, bacterial taxa belonging to the phyla Firmicutes are known to be involved in the degradation of complex carbohydrates (not absorbed by the host) and in the production of SCFAs (Thibodeau et al, 2015). Thus, the SCFAs production by Firmicutes might, at least partially, explain their dominance in the infected birds, which have a high SCFAs requirement as a source of energy for C. jejuni to colonize the chicken gut.…”

Differences in host breed and diet influence colonization by Campylobacter jejuni and induction of local immune responses in chicken

“…Recent studies have shown that maize- or wheat-based diets, which contain different levels of crude protein, can alter the viscosity of gut content and histomorphology of the chicken gut [11], and subsequently reduce C. jejuni colonization in broilers [9]. Changes in diet due to different protein sources or non-antibiotic feed additive may modify the gastrointestinal environment creating disturbances in the resident microbiota thus allowing—directly or indirectly—either a proliferation or reduction of bacterial pathogens [10, 55]. We observed that LT-bf birds, which were inoculated with C. jejuni at 1 dph, showed a significantly higher numbers of CFU of C. jejuni compared to LT-lf chickens ( p  < 0.05).…”

“…The reduction of C. jejuni colonization rates may be a reachable goal [5, 6]. While pro- and prebiotics have led to inconsistent results [7–9], other control measures including feeding strategies and the use of more resistant breeds may allow significant reduction of C. jejuni colonization [10–12]. …”

“…It is not fully clear how different feeding strategies may alter the colonization pattern of the intestinal bacteria, the development of local immunity and subsequently modulate local immune reactions in response to C. jejuni colonization. Most of these studies were conducted in broilers and focused on the relationship between C. jejuni colonization and nutritional changes [10, 30–32]. …”

Investigating the Association Between the Caecal Microbiomes of Broilers and Campylobacter Burden

“…Considering that all birds within a flock have the same age, feed, and similar genetics it may be expected that the profiles of individual birds within a flock would be similar. However, a recent study has shown that there is high bird to bird variation, within the same flock (Thibodeau et al, 2015). Knowledge of the magnitude of microbiome genetic variation within and between flocks is still lacking.…”