I. Reyes-Herrera

The natural feed additive caprylic acid decreases Campylobacter jejuni colonization in market-aged broiler chickens

Campylobacter causes human foodborne illness, and epidemiological evidence indicates poultry and poultry products as a significant source of human infection. Decreasing Campylobacter in the poultry intestinal tract would decrease contamination of poultry products. Caprylic acid is a medium-chain fatty acid reported to be effective in killing a variety of bacterial pathogens, including Campylobacter jejuni, but its effect has not been investigated in the control of C. jejuni in preslaughter market-aged poultry already colonized with this bacterium. The objective of this study was to determine the therapeutic effect of caprylic acid on C. jejuni counts in the cecal contents of 42-d-old chickens. Four trials were conducted. In the first 2 trials, day-of-hatch chicks (n = 60 per trial) were assigned to 6 treatment groups (n = 10 birds per treatment group): positive controls (Campylobacter, no caprylic acid), 0.7 or 1.4% of caprylic acid in feed for the last 3 d of the trial with or without a 12-h feed withdrawal. Treatments were similar for trials 3 and 4 except the doses used were 0.35 or 0.7% caprylic acid supplementation for the last 7 d of the trial. On d 42, ceca were collected and Campylobacter counts determined. The supplementation of caprylic acid at 0.35 and 0.7% consistently decreased (P < 0.05) the colonization of C. jejuni in the chicken ceca compared with positive control treatment. When these treatments were evaluated after a 12-h feed withdrawal period, 0.7% caprylic acid decreased Campylobacter colonization in the 3-d treatment supplementation. Body weight and feed consumption did not differ between the caprylic acid and control groups. The results suggest that therapeutic supplementation of caprylic acid in the feed can effectively decrease Campylobacter in market-aged chickens and may be a potential treatment for decreasing pathogen carriage in poultry.

Campylobacter susceptibility to ciprofloxacin and corresponding fluoroquinolone concentrations within the gastrointestinal tracts of chickens

Aims:  This study evaluated the relationship between Campylobacter susceptibility and enteric fluoroquinolone concentrations in chickens treated with different doses of enrofloxacin.

Therapeutic Supplementation of Caprylic Acid in Feed Reduces Campylobacter jejuni Colonization in Broiler Chicks

ABSTRACT Poultry colonized with Campylobacter species are a significant source of human food-borne illness. The therapeutic use of the medium chain fatty acid caprylic acid consistently reduced enteric C. jejuni colonization in chicks by 3 to 4 logs in three separate trials. These results support caprylic acids potential to reduce Campylobacter carriage in poultry.

Concentrations of antibiotic residues vary between different edible muscle tissues in poultry.

Antibiotics are used by veterinarians and producers to treat disease and improve animal production. The federal government, to ensure the safety of the food supply, establishes antibiotic residue tolerances in edible animal tissues and determines the target tissues (e.g., muscle) for residue monitoring. However, when muscle is selected as the target tissue, the federal government does not specify which type of muscle tissue is used for monitoring (e.g., breast versus thigh). If specific muscle tissues incorporate residues at higher concentrations, these tissues should be selected for residue monitoring. To evaluate this possibility in poultry, chickens were divided into four groups and at 33 days of age were dosed with enrofloxacin (Baytril), as per label directions, at either 25 ppm for 3 days, 25 ppm for 7 days, 50 ppm for 3 days, or 50 ppm for 7 days. Breast and thigh muscle tissues were collected from each bird (n = 5 birds per day per group) during the dosing and withdrawal period, and fluoroquinolone concentrations were determined. The results indicate higher overall enrofloxacin concentrations in breast versus thigh muscle for each treatment group (P < 0.05). These data indicate, at least for enrofloxacin, that not all muscle tissues incorporate antibiotics at the same concentrations. These results may be helpful to regulatory agencies as they determine what tissues are to be monitored to ensure that the established residue safety tolerance levels are not exceeded.

Caprylic acid reduces enteric Campylobacter colonization in market-aged broiler chickens but does not appear to alter cecal microbial populations.

Campylobacter is a leading cause of foodborne illness in the United States, and epidemiological evidence indicates poultry products to be a significant source of human Campylobacter infections. Caprylic acid, an eight-carbon medium-chain fatty acid, reduces Campylobacter colonization in chickens. How caprylic acid reduces Campylobacter carriage may be related to changes in intestinal microflora. To evaluate this possibility, cecal microbial populations were evaluated with denaturing gradient gel electrophoresis from market-age broiler chickens fed caprylic acid. In the first trial, chicks (n = 40 per trial) were assigned to four treatment groups (n = 10 birds per treatment group): positive controls (Campylobacter, no caprylic acid), with or without a 12-h feed withdrawal before slaughter; and 0.7% caprylic acid supplemented in feed for the last 3 days of the trial, with or without a 12-h feed withdrawal before slaughter. Treatments were similar for trial 2, except caprylic acid was supplemented for the last 7 days of the trial. At age 14 days, chicks were orally challenged with Campylobacter jejuni, and on day 42, ceca were collected for denaturing gradient gel electrophoresis and Campylobacter analysis. Caprylic acid supplemented for 3 or 7 days at 0.7% reduced Campylobacter compared with the positive controls, except for the 7-day treatment with a 12-h feed withdrawal period. Denaturing gradient gel electrophoresis profiles of the cecal content showed very limited differences in microbial populations. The results of this study indicate that caprylic acids ability to reduce Campylobacter does not appear to be due to changes in cecal microflora.

Campylobacter biofilm phenotype exhibits reduced colonization potential in young chickens and altered in vitro virulence

In this study, we evaluated the ability of different Campylobacter phenotypes (biofilm versus planktonic) to colonize young poultry. It has been suggested that a persistent Campylobacter biofilm reservoir may be involved in the initial contamination of poultry flocks. Campylobacter jejuni cultured adherent to agar was utilized as the biofilm model and C. jejuni cultured in broth was evaluated as the planktonic model. In 2 independent trials, 1-d-old broiler chicks were given 1 of 3 treatments: 1) 10(5) cfu.mL(-1) of C. jejuni cultured in broth, 2) 10(5) cfu.mL(-1) of C. jejuni cultured adherent to agar, or 3) no C. jejuni (negative control). Cecal contents of all birds were evaluated by culturing 12 d after the initial challenge with C. jejuni. In both trials, birds challenged with C. jejuni cultured in broth had approximately 3 to 4 log higher cecal Campylobacter concentration than birds challenged with C. jejuni cultured adherent to agar. Using 2 cell lines (INT 407 and DF1), virulence of C. jejuni cultured in broth versus adherent to agar also was evaluated by challenging monolayers of eukaryotic cells with 1 of 3 treatments: 1) 10(5) cfu.mL(-1) of C. jejuni cultured in broth, 2) 10(5) cfu.mL(-1) of C. jejuni cultured adherent to agar, or 3) no C. jejuni (negative control). The virulence study also showed differences of C. jejuni cultured in broth or agar in attachment and invasion abilities to tissue culture cells, but differences were not as consistent as with the chick colonization study. This study indicates that phenotype may play a role in colonization of chickens and virulence by C. jejuni.

Antibiotic residues distribute uniformly in broiler chicken breast muscle tissue.

Use of antibiotics by the poultry industry has the potential to produce residues in edible tissues. In order to protect consumers, the U.S. federal government performs extensive evaluations to quantify residues in edible tissues to ensure that concentrations do not exceed the tolerance level. However, in the case of muscle tissue, the regulatory process does not differentiate between different edible muscle types in poultry. Previous studies performed by our laboratory determined higher fluoroquinolone residue concentrations in breast versus thigh muscle. Thus, if thigh tissues were used for residue monitoring, it would not accurately depict the higher concentrations. It is also possible that residue concentrations vary within tissues. To evaluate this possibility, fluoroquinolone antibiotic residues were determined for different breast sections. One hundred sixty chickens were randomly divided into four groups and dosed at 33 days of age with the fluoroquinolone antibiotic, enrofloxacin (Baytril), at either 25 ppm for 3 days, 25 ppm for 7 days, 50 ppm for 3 days, or 50 ppm for 7 days. Breast fillets were collected from each bird (n = 5 birds per day per group) during the dosing and withdrawal period. Each breast was divided into four sections (upper left, upper right, lower left, and lower right) that were analyzed as individual samples for determination of fluoroquinolone concentration. Our results indicated no significant difference (P > 0.05) in the levels of enrofloxacin residues between breast sections during the dosing or withdrawal periods. Consequently, samples can be collected from any breast section to evaluate fluoroquinolone residue concentrations during the regulatory monitoring process.

Water administration of the medium-chain fatty acid caprylic acid produced variable efficacy against enteric Campylobacter colonization in broilers.

Campylobacter is one of the most common causes of foodborne illness, and poultry are considered a primary source of Campylobacter infections. Caprylic acid, an 8-carbon fatty acid, has been shown in previous studies to reduce enteric cecal Campylobacter concentrations in poultry when administered in the feed. For greater ease of application for producers, a water-soluble form of caprylic acid, sodium octanoate, was evaluated for efficacy against enteric Campylobacter. The first trial consisted of 70 birds in 7 groups (n = 10 chicks/group): an untreated control and 6 other groups that were challenged with Campylobacter at d 3 and that received 0, 0.175, 0.35, 0.7, 1.4, or 2.8% water-soluble caprylic acid in water 3 d before necropsy at d 14. The second trial consisted of 80 birds in 8 groups (n = 10 chicks/group): an untreated negative control and 7 other groups, all of which were challenged with Campylobacter at d 3 and received 0, 0.044, 0.088, 0.175, 0.35, 0.7, or 1.4% water-soluble caprylic acid for 3 d before necropsy at d 14. In trial 1, only the 0.175% dose caused a reduction in cecal Campylobacter counts in comparison with the positive control (approximately a 3-log reduction). In trial 2, no treatment reduced Campylobacter counts compared with the positive control. Unlike the efficacy of caprylic acid in feed, treatment with caprylic acid in water had an inconsistent effect on intestinal Campylobacter counts.

Targeting motility properties of bacteria in the development of probiotic cultures against Campylobacter jejuni in broiler chickens.

Campylobacter is the leading cause of gastroenteritis worldwide. Campylobacter is commonly present in the intestinal tract of poultry, and one strategy to reduce enteric colonization is the use of probiotic cultures. This strategy has successfully reduced enteric colonization of Salmonella, but has had limited success against Campylobacter. In an effort to improve the efficacy of probiotic cultures, we developed a novel in vitro screening technique for selecting bacterial isolates with enhanced motility. It is proposed that motility-selected bacteria have the marked ability to reach the same gastrointestinal niche in poultry and competitively reduce C. jejuni. Bacterial isolates were collected from ceca of healthy chickens, and motile isolates were identified and tested for anti-Campylobacter activity. Isolates with these properties were selected for increased motility by passing each isolate 10 times and at each passage selecting bacteria that migrated the farthest during each passage. Three bacterial isolates with the greatest motility (all Bacillus subtilis) were used alone or in combination in two chicken trials. At day of hatch, chicks were administered these isolates alone or in combination (n=10/treatment, two trials), and chicks were orally challenged with a mixture of four different wild-type strains of C. jejuni (∼10(5) CFU/mL) on day 7. Isolate 1 reduced C. jejuni colonization in both of the trials (p<0.05). A follow-up study was conducted to compare isolate 1 subjected to enhanced motility selection with its nonselected form. A reduction (p<0.05) in Campylobacter colonization was observed in all three trials in the chickens dosed using isolate with enhanced motility compared to the control and unselected isolate. These findings support the theory that the motility enhancement of potential probiotic bacteria may provide a strategy for reduction of C. jejuni in preharvest chickens.

The relationship between blood and muscle samples to monitor for residues of the antibiotic enrofloxacin in chickens

In 2005, the US Food and Drug Administration withdrew approval for use of enrofloxacin in poultry, thus effectively imposing zero tolerance for residues of this antibiotic in poultry. Conventional residue monitoring for most antibiotics, including enrofloxacin, involves removing poultry carcasses from the processing line and collecting muscle tissues for analysis. Because of the loss of valuable edible products and the difficulties and expense of sampling all the carcasses, only a small portion of carcasses are tested for violative residues. Unlike muscle tissue, blood is readily available from all birds at the beginning of processing and may be used to screen for illegal residues in all poultry carcasses. It is unknown, however, if enrofloxacin concentrations in blood are predictive of muscle concentrations. In an effort to evaluate this relationship, 156 broiler chickens, 5 wk of age, were dosed with either 25 or 50 µg/mL of enrofloxacin for 3 or 7 d, respectively, in the drinking water. Blood and muscle samples were collected at 0, 1, 3, 6, 12, and 24 h (n = 6 birds/group) during the first dosing day, every 48 h during the dosing period, and every 12 h during the withdrawal period for up to 60 h after withdrawal. Enrofloxacin residues were determined in all blood and tissue samples during the dosing periods and in most of the withdrawal period for both doses. These results support the potential to use blood to screen for illegal enrofloxacin residues in edible poultry tissues in an effort to protect the human food supply.