In the last 20 years, Campylobacter has emerged as the most commonly reported cause of bacterial gastroenteritis in humans worldwide. Affected humans show clinical signs of acute diarrhea or more severe complications including Guillain-Barré syndrome and arthritis. The cost of campylobacteriosis to public health and to lost productivity in the EU is estimated by the European Food Safety Authority (EFSA) to be around €2.4 billion a year.

Poultry are generally recognised to play a significant role in human campylobacteriosis where consumption or mishandling of raw or under cooked poultry meat, or contamination of ready to eat foods that have been in contact with raw poultry meat are considered the most common sources of infection. As consumption and mishandling of raw or undercooked poultry meat is the main cause of Campylobacter transmission to humans, reducing chicken colonisation by this bacterium might reduce in the incidence of human infections.

One of the challenges associated with campylobacteriosis control is that Campylobacter behaves as a commensal microorganism in healthy poultry without causing any clinical diseases. It inhabits the mucus layer of the caecum but does not penetrate the intestinal cells.

Several tools are used to to control enteric pathogens in poultry. Competitive exclusion strategies and the use of specific probiotics and synbiotics have shown to be effective means of manipulating or managing the composition of the microbial population in the gastrointestinal tract of poultry, and thus protecting poultry flocks from pathogenic bacteria.

Probiotics for Poultry

A multinational project funded by the EU brought together five industrial and three research partners for the purpose of developing a well-defined and safe multi-species probiotic product for poultry.

Numerous intestinal bacteria were isolated out of the gut of several healthy chickens and thoroughly characterised by combining morphological, physiological and genotypic methods. The most promising strains were evaluated for important probiotic criteria like the inhibition of pathogenic bacteria.

Based on these results, a product consisting of strains belonging to the genera Enterococcus, Pediococcus, Lactobacillus and Bifidobacterium (PoultryStar®, Biomin GmbH) was designed. As the probiotic strains were able to inhibit Campylobacter jejuni (the main cause of human campylobacteriosis) in vitro, the efficacy of PoultryStar on Campylobacter jejuni was evaluated in experimental challenge trials using experimentally infected broilers.

PoultryStar and Campylobacter Control in Broiler Chickens

Research findings from the CESAC (Centre de Sanitat Avícola de Catalunya i Aragó) revealed that the prophylactic feeding of the poultry-specific, multi-species probiotic PoultryStar to broilers caused a significant decrease in the caecal colonisation of Campylobacter jejuni in two independent challenge trials with experimentally infected broilers.

Commercial day-old broiler chicks (Ross 308, mixed sex) were procured from a commercial hatchery with certificate of origin and health. The caeca of 10 randomly selected birds were harvested and tested for the presence of Campylobacter species to ensure that the experimental birds were Campylobacter negative.

The remaining birds were wing-tagged and placed in individual pens with fresh wood shavings litter. Feed and water were provided ad libitum. Birds received a standard non-medicated corn-soy based starter diet. Temperature, heating and ventilation followed the commercial recommendation.

Method

Two experiments were conducted to evaluate the efficacy of PoultryStar on Campylobacter jejuni colonisation in broiler chickens.

Experiment 1: All birds were oral gavaged with 0.1ml of a solution containing 10⁵ cfu per ml of a field strain of Campylobacter jejuni on day 1.

Forty-four day-old broiler chicks were randomly assigned to two groups, a Campylobacter-challenged positive control group and a Campylobacter-challenged group which received an additional 2mg per bird and day of PoultryStar sol via drinking water.

Experiment 2: All birds were challenged with Campylobacter jejuni on day 1 by introducing in each group four seeder birds orally gavaged with 0.1ml of a solution containing 10⁵ cfu per ml of a field strain of Campylobacter jejuni.

Seventy-eight day-old broiler chicks were randomly assigned to three groups: a Campylobacter-challenged positive control group; a Campylobacter-challenged group which received an additional 2mg per bird and day of PoultryStar sol via drinking water; and a Campylobacter-challenged group which received an additional 20mg per bird and day of PoultryStar sol via drinking water.

On days 8 and 15 of both experiments, 10 birds from each group were euthanised and their caeca harvested for individual quantitative culture of Campylobacter.

Results

Experiment 1: The application of 2mg per bird and day of Poultry-Star sol via drinking water significantly reduced (P=0.001) the caecal colonisation of Campylobacter jejuni.

On day 8: Ten of 12 birds in the PoultryStar group had Campylobacter counts that were less than 3 log cfu per gramme, which was significantly lower than the mean log count in the positive control group, 6.67 log cfu per gramme (P=0.001).

On day 15: All the birds from the positive control group had counts higher than 8 log cfu per gramme. However, in the PoultryStar group, the maximum count was significantly reduced (P=0.001) to 4.10 log cfu per gramme and half the birds had counts less than 2 log cfu per gramme (Table 1).

Table 1. Experiment 1, days 8 and 15. Campylobacter content in caecum (log cfu/g) after challenging with 105cfu/ml of a field strain of Campylobacter jejuni on day 1
	Positive control	PoultryStar 2mg/bird/day	Positive control	PoultryStar 2mg/bird/day
Bird/Age	Day 8		Day 15
1	7.92	<3	>8	3.89
2	7.74	3.00	>8	3.72
3	3.90	<3	>8	4.10
4	6.45	4.38	>8	3.30
5	4.85	<3	>8	<2
6	7.53	<3	>8	2.78
7	6.79	<3	>8	<2
8	7.86	<3	>8	<2
9	7.51	<3	>8	4.18
10	5.18	<3	>8	<2
11	>8	<3	>8	<2
12	<3	<3	>8	<2
Average	6.67a	4.10b	>8a	3.82b
a,b Means within a row with different letters differ significantly (P=0.001) Source: Ghareeb et al., 2012

Experiment 2: The application of 2mg per bird and day and also 20mg per bird and day of PoultryStar sol via drinking water significantly reduced (P=0.001) the caecal colonisation of Campylobacter jejuni.

On days 8 and 15, Campylobacter counts in the caecal content of the PoultryStar group were less than 2 log cfu per gramme, whereas the mean log counts in the positive control group were 7.81 log cfu per gramme on day 8 and 7.85 log cfu per gramme on day 15 (P=0.001), respectively (Tables 2a and 2b). Compared with the controls, the PoultryStar groups showed a 6-log reduction in the caecal colonisation of Campylobacter jejuni. The lower dose of PoultryStar was also effective in reducing Campylobacter counts.

Table 2a. Experiment 2, day 8. Campylobacter content in the caecum, log cfu/g, after challenging with 105cfu/ml of a field strain of Campylobacter jejuni on day 1
Bird (day 8)	Positive control	PoultryStar 2mg/bird/day	PoultryStar 20mg/bird/day
1	8.52	<2	<2
2	7.78	<2	<2
3	8.15	<2	<2
4	6.48	<2	<2
5	6.30	<2	<2
6	9.02	<2	<2
7	7.60	<2	<2
8	9.60	<2	<2
9	8.38	<2	<2
10	6.30	<2	<2
Average	7.81a	<2b	<2b
a,b Means within a row with different letters differ significantly (P=0.001) Source: Ghareeb et al., 2012

Table 2b. Experiment 2, day 15. Campylobacter content in the caecum, log cfu/g, after challenging with 105cfu/ml of a field strain of Campylobacter jejuni on day 1
Bird (day 15)	Positive control	PoultryStar 2mg/bird/day	PoultryStar 20mg/bird/day
1	8.00	<2	<2
2	7.78	<2	<2
3	7.85	<2	<2
4	7.00	<2	<2
5	7.48	<2	<2
6	8.77	<2	<2
7	7.30	<2	<2
8	8.11	<2	<2
9	8.2	<2	<2
10	8.00	<2	<2
Average	7.85a	<2b	<2b
a,b Means within a row with different letters differ significantly (P=0.001) Source: Ghareeb et al., 2012

Improved Immunity

The results of these studies showed that the use of probiotics can help to improve the natural defence of birds against enteric bacteria and can be used as an alternative and effective strategy to antibiotics in livestock, thus reducing bacterial contamination of raw poultry meat.

The inclusion of the multi-species synbiotic PoultryStar significantly reduced caecal colonisation of Campylobacter jejuni in broilers by its marked antimicrobial activities.

This shows the beneficial effects of PoultryStar towards reducing Campylobacter prevalence in poultry and subsequently, the incidence of campylobacteriosis in humans.

July 2014