The enhancement of Th1 immune response by anti-PD-L1 antibody in cattle infected with Mycobacterium avium subsp. paratuberculosis.

Johne's disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP), is a chronic enteritis of ruminants. Previous studies have shown that programmed death-ligand 1 (PD-L1) is associated with the disease progression, and PD-L1 blockade activates MAP-specific Th1 responses in vitro. Here, we performed anti-PD-L1 antibody administration using 2 MAP-infected cattle at the late subclinical stage of infection. After administration, bacterial shedding was reduced or maintained at a low level. Additionally, MAP-specific Th1 cytokine production was upregulated, and CD69 expression was increased in T cells. Collectively, the treatment has a potential as a novel control method against Johne's disease.

Plant- and Fish-Derived n-3 PUFAs Suppress Citrobacter Rodentium-Induced Colonic Inflammation.

SCOPE: Marine-derived n-3 PUFAs may ameliorate inflammation associated with inflammatory bowel diseases. Plant-derived n-3 PUFAs are thought to be inferior owing to shorter chain lengths. The aim of this study is to compare the impact of plant- and fish-derived PUFAs on murine colitis. METHODS AND RESULTS: C57BL/6 mice are fed high fat (36% kcal) diets with either 2.5% w/w sunflower oil (SO), flaxseed oil (FSO), ahiflower oil (AO), or fish oil (FO). After 4 weeks, mice are orogastrically challenged with Citrobacter rodentium (108 CFU) or sham gavaged. Fecal shedding is assayed at 2, 7, 10, and 14 days post infection (PI), and fecal microbiota at 14 days PI. Colonic inflammation and lipid mediators are measured. Supplementation regulates intestinal inflammation with crypt lengths being 66, 73, and 62 ±17 µm shorter (compared to SO) for FSO, AO, and FO respectively, p < 0.01. FSO blunts pathogen shedding at the peak of infection and FSO and AO both enhance fecal microbial diversity. FO attenuates levels of lipoxin and leukotriene B4 while plant oils increase pro-resolving mediator concentrations including D, E, and T-series resolvins. CONCLUSION: Plant and fish n-3 PUFAs attenuate colitis-induced inflammation while exhibiting characteristic pro-resolving lipid mediator metabolomes. Plant oils additionally promote microbial diversity.

Clinically Relevant Campylobacter jejuni Subtypes Are Readily Found and Transmitted within the Cattle Production Continuum but Present a Limited Foodborne Risk.

Increasing evidence exists for the role that cattle play in the epidemiology of campylobacteriosis. In this study, the prevalence and distribution of Campylobacter jejuni were longitudinally examined at the subspecies level in the beef cattle production continuum. Animals were subdivided into two groups: those that were not administered antibiotics and those that were administered the antimicrobial growth promoter chlortetracycline and sulfamethazine (AS700). Samples were longitudinally collected throughout the confined feeding operation (CFO) period and during the slaughter process, and C. jejuni was isolated and genotyped to assess subtype richness and to elucidate transmission dynamics from farm to fork. The bacterium was frequently isolated from cattle, and the bacterial densities shed in feces increased over the CFO period. Campylobacter jejuni was also isolated from digesta, hides, the abattoir environment, and carcasses. The administration of AS700 did not conspicuously reduce the C. jejuni densities in feces or within the intestine but significantly reduced the bacterial densities and the diversity of subtypes on abattoir samples. All cattle carried multiple subtypes, including clinically relevant subtypes known to represent a risk to human health. Instances of intra-animal longitudinal transmission were observed. Although clinically relevant subtypes were transmitted to carcasses via direct contact and aerosols, the bacterium could not be isolated nor could its DNA be detected in ground beef regardless of treatment. Although the evidence indicated that beef cattle represent a significant reservoir for C. jejuni, including high-risk subtypes strongly associated with the bovine host, they do not appear to represent a significant risk for direct foodborne transmission. This implicates alternate routes of human transmission.IMPORTANCE Limited information is available on the transmission of Campylobacter jejuni subtypes in the beef production continuum and the foodborne risk posed to humans. Cattle were colonized by diverse subtypes of C. jejuni, and the densities of the bacterium shed in feces increased during the confined feeding period. Campylobacter jejuni was readily associated with the digesta, feces, and hides of cattle entering the abattoir, as well as the local environment. Moreover, C. jejuni cells were deposited on carcasses via direct contact and aerosols, but the bacterium was not detected in the ground beef generated from contaminated carcasses. We conclude that C. jejuni bacterial cells associated with beef cattle do not represent a significant risk through food consumption and suggest that clinically relevant subtypes are transmitted through alternate routes of exposure.

Bacillus pumilus probiotic feed supplementation mitigates Lawsonia intracellularis shedding and lesions.

The causative agent of ileitis, Lawsonia intracellularis, is commonly associated with diarrhea and reduced weight gain in growing pigs. The effect of in-feed probiotics on L. intracellularis infection dynamics was evaluated. In brief, 70 2.5-week-old-pigs were randomly divided into six groups with 10-20 pigs each. All pigs were fed an age appropriate base ration for the duration of the study, which was supplemented with one of three Bacillus strains including B. amyloliquefaciens (T01), B. licheniformis (T02) and B. pumilus (T03). Another group was orally vaccinated with a commercial live L. intracellularis vaccine (VAC) at 3 weeks of age. At 7 weeks of age, T01-LAW, T02-LAW, T03-LAW, VAC-LAW and the POS-CONTROL groups were challenged with L. intracellularis while the NEG-CONTROL pigs were not challenged. All pigs were necropsied 16 days later. By the time of inoculation, all VAC-LAW pigs had seroconverted and at necropsy 10-65% of the pigs in all other challenged groups were also seropositive. The results indicate a successful L. intracellularis challenge with highest bacterial DNA levels in POS-CONTROL pigs, VAC-LAW pigs and T01-LAW pigs. There was a delay in onset of shedding in T02-LAW and T03-LAW groups, which was reflected in less severe macroscopic and microscopic lesions, reduced intralesional L. intracellularis antigen levels and a lower area under the curve for bacterial shedding. Under the study conditions, two of the probiotics tested suppressed L. intracellularis infection. The obtained findings show the potential of probiotics in achieving antibiotic-free control of L. intracellularis.

Effect of a direct-fed microbial and prebiotic on performance and intestinal histomorophology of turkey poults challenged with Salmonella and Campylobacter.

Salmonella and Campylobacter are leading human foodborne pathogens commonly associated with poultry and poultry products, and several methods to control these pathogens have been applied to poultry production. This study was conducted to evaluate the effect of CALSPORIN, (CSP), a direct-fed microbial (DFM), and yeast cell wall (Saccharomyces cervisiae, IMW50, a mannanoligosaccharide (MOS)-based prebiotic, on performance, levels of Salmonella and Campylobacter in the feces, and intestinal histomorphometry in turkey poults. A 21-day battery cage study was conducted using 4 dietary treatments, including: an unsupplemented basal diet (corn and soybean-based) as negative control (NC); basal diet supplemented with 0.05% DFM; basal diet supplemented with 0.05% MOS; and basal diet supplemented with 0.05% mixture of DFM and MOS at equal proportions. Female Large White turkey poults (n = 336) were randomly distributed in 6 electrically-heated battery cages with 4 treatments and 12 replicates per treatment (7 poults per replicate pen). The first 16 pens were not inoculated with bacteria, while poults in pens 17 to 32 were orally challenged at day 7 with 105 CFU Salmonella Heidelberg and the poults in pens 33 to 48 were orally challenged at day 7 with 105 CFU Campylobacter jejuni. Feed consumption, body weight, and feed conversion ratio were measured weekly and at the end of the experiment. At day 21, fresh fecal samples from each pen were collected for Salmonella and Campylobacter enumeration and ileal tissue samples were collected from 1 bird per pen for histomorphology examination. DFM and MOS supplementation was accompanied with reduced levels of Salmonella shed by the treated birds compared to the control group, and with increased body weight (P ≤ 0.05). The surface area of villi increased in the MOS-supplemented group compared to the control group (P ≤ 0.05). There was a significant difference in V:C ratio between supplemented groups and control group (P ≤ 0.05). Based on these results, there is potential for CALSPORIN and IMW50 to reduce Salmonella shedding in feces, enhance ileal mucosal health, and improve growth performance of turkey poults.

Effect of supplemental threonine above requirement on growth performance of Salmonella typhimurium challenged pigs fed high-fiber diets1.

It was shown previously that high dietary fiber (DF) and immune system stimulation (ISS) with systemic Escherichia coli lipopolysaccharide independently increased the threonine (Thr) requirement to maximize growth performance and protein deposition (PD). However, no additive effects on the Thr requirement were observed when both DF and ISS were present. The objective of the present study was to investigate whether supplementing Thr to meet previously estimated requirements for high DF and systemic immune challenge would maintain performance of pigs exposed to an enteric immune challenge when fed high DF. A total of 128 pigs (22.6 ± SD = 1.6 kg initial BW) were assigned to 1 of 4 dietary treatments in a 2 × 2 factorial arrangement in a randomized complete block design (n = 8 pens/treatment and 4 pigs/pen) for 28 d. Treatments were a low-fiber (LF; 13% total DF) or high-fiber (HF; 20% total DF) diet with either a standard (STD; 0.65% SID) or supplemental (SUP; 0.78% SID) Thr level. After a 7-d adaptation, pigs were orally inoculated with 2 mL (2.3 × 109 CFU/mL) of Salmonella typhimurium (ST). Blood samples and rectal swabs were obtained and rectal temperature recorded to determine clinical responses and ST shedding. On day 7 postinoculation, 1 pig/pen was euthanized and mesenteric lymph nodes, spleen, and digesta (ileum, cecum, and colon) were sampled to assess ST colonization and translocation. Body weight and feed intake were recorded on day 0, 7, and 21 postinoculation to calculate ADG, ADFI, and G:F. Rectal temperature increased (P < 0.05) 24 h postinoculation and remained elevated at day 6. Serum albumin concentration decreased (P < 0.05), whereas haptoglobin concentration increased (P < 0.05) postinoculation. There was no fiber or Thr effect (P > 0.05) on ST counts in the ileum and cecum, but a fiber × Thr interaction (P < 0.05) was observed in the colon. Supplemental Thr improved (P < 0.05) growth performance in LF- and HF-fed challenged pigs. However, performance of supplemented HF challenged pigs was less than (P < 0.05) supplemented LF challenged pigs. These results suggest that Thr supplemented to meet requirements for high DF and systemic immune challenge was not sufficient to maintain growth performance of pigs fed HF diets and challenged with an enteric pathogen.

Salmonella shedding and seropositivity and its association with in-feed flavophospholipol in nursery pigs.

The objective of this study was to assess the impact of in-feed flavophospholipol on Salmonella shedding and antibody response in nursery pigs. Weaned pigs were fed either a diet containing 4 ppm flavophospholipol (n = 16) or a non-medicated feed (n = 16) for 36 d. All pigs were orally challenged with a 2-mL dose of 108 colony-forming units (CFUs)/mL of Salmonella Typhimurium on Days 7 and 8 of the trial. On Day 36, all pigs were euthanized and samples were collected from the liver, spleen, and ileocecal lymph nodes. Fecal and tissue samples were quantitatively cultured for Salmonella and serum samples were tested for the presence of the Salmonella antibody by enzyme-linked immunosorbent assay (ELISA). There was no difference between the 2 groups in antibody response and the presence of Salmonella in feces and tissue (P > 0.05). Medicating nursery diets with flavophospholipol at 4 ppm did not appear to reduce Salmonella infection in nursery pigs.

L'objectif de la présente étude était d'évaluer l'impact de l'ajout de flavophospholipol dans l'aliment sur l'excrétion de Salmonella et la réponse en anticorps chez des porcs en pouponnière. Des porcs sevrés ont été nourris avec soit une diète contenant 4 ppm de flavophospholipol (n = 16) ou une diète non-médicamentée (n = 16) pendant 36 j. Tous les porcs ont reçu oralement une dose de 2 mL de 108 unités formatrices de colonies (UFC)/mL de Salmonella Typhimurium aux Jours 7 et 8 de l'essai. Au Jour 36, tous les porcs ont été euthanasiés et on préleva des échantillons de foie, rate, et noeuds lymphatiques iléo-caecaux. Des échantillons de fèces et de tissus ont été cultivés pour quantifier le nombre de Salmonella et des échantillons de sérum furent testés pour la présence d'anticorps contre Salmonella par épreuve immunoenzymatique (ELISA). Il n'y avait pas de différence entre les deux groupes quant à la réponse en anticorps et la présence de Salmonella dans les fèces et les tissus (P > 0,05). L'ajout de 4 ppm de flavophospholipol à la diète en pouponnière ne semble pas réduire l'infection par Salmonella chez les porcs en pouponnière.(Traduit par Docteur Serge Messier).

Effects of resveratrol on shedding and pathological dynamics in experimental B. melitensis infection in dexamethasone-treated nonpregnant Boer goats.

Brucellosis constitutes an infectious re-emerging zoonosis. Spread of diseases could be exacerbated by stress-induced immunosuppression. This study evaluated relationship between Brucella melitensis infection, shedding dynamics, dexamethasone-induced stress, pathological alterations and resveratrol ameliorative effects in goats. Twelve nonpregnant goats were divided into four groups A, B, C, and D of three animals each. Groups A and B were administered 107 CFU/mL of B. melitensis ocularly, 21 days prior to 7 days consecutive administration of dexamethasone (2 mg/kg). Group A was further administered resveratrol (5 mg/kg) intravenously for 5 consecutive days from day 31 post B. melitensis inoculation. Group C was administered similar dose of B. melitensis while group D was inoculated normal saline. Blood, nasal, ocular, and vaginal swabs were collected at intervals for analysis. The does were sacrificed at day 42 post inoculation (pi). Tissues were collected for tissue bacterial load determination, histopathology, and immunohistochemistry. Dexamethasone administration from day 21 pi increased the frequency in the shedding dynamics, tissue bacterial load, pathological alterations (frequency of microgranuloma and intensity of immunostaining) in group B while 5 days treatment with resveratrol following dexamethasone administration significantly reduced tissue bacterial load, decline in shedding dynamics, and ameliorate damage by dexamethasone administration/B. melitensis infection.

Cultivable microbiota and pulmonary lesions in polymicrobial bovine pneumonia.

In the present study, the spectrum of bacterial pathogens in the nasal shedding during disease process and in pneumonic lungs of dead animals was studied. A total of 288 clinical samples from cattle and buffaloes comprising of nasal swabs, blood, tracheal swabs, heart blood and lung tissue samples were collected from diseased (n = 190) and dead animals (n = 98). The recovered bacterial isolates were characterized by biochemical reactions, Matrix Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI TOF-MS) and the 16S rRNA sequence analysis. The predominant bacterial isolates associated were Pasteurella multocida, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. The emerging pathogens causing bovine pneumonia identified were Leclercia spp., Stenotrophononas maltophila and Staphylococcus sciuri. Bacteriological examination of pneumonic lungs samples revealed 96.9% samples to be positive for polymicrobial isolation. Macroscopical lesions of lungs exhibited various stages and types of pneumonia with variable degree of haemorrhages, oedema and emphysema. Histopathologically, the fibrinous bronchopneumonia was observed to be the most frequent lesions seen in bovine pneumonia. Multi-drug resistance (MDR) was observed in 10% of P. multocida isolates. The resistance was seen for penicillin, cephalosporins and fluoroquinolones. Multi-drug resistance was seen in 90% of the E.coli tested. K. pneumoniae, E. hormaechei, E. cloacae, P. putida and Leclercia spp. identified were found to be multi-drug resistant. Understanding the etiological diversity of bacterial pathogens of bovine pneumonia may provide information for the better choice of therapeutics and health management.

Assessment of the efficacy of an autogenous vaccine against Yersinia pseudotuberculosis in young Merino sheep.

AIMS To assess the efficacy of an autogenous vaccine against Yersinia pseudotuberculosis III in preventing clinical disease and deaths due to yersiniosis in young Merino sheep, and to determine the effect of vaccination on the prevalence of faecal shedding of pathogenic Yersinia spp., daily liveweight gain, and development of antibodies to Yersinia spp. following vaccination and natural exposure. METHODS In six groups (three groups each from two farms) of young Merino sheep, 148-150 animals were systematically allocated to be vaccinated twice with an autogenous, formalin- killed bacterin vaccine containing Y. pseudotuberculosis serotype III or to remain non-vaccinated. All vaccinated and non-vaccinated sheep were run together in their original groups throughout the trial. Faecal and blood samples were collected, and liveweight measured, at the time of vaccination and subsequently over a 6-month period to determine faecal shedding of Y. enterocolitica and Y. pseudotuberculosis, seroprevalence of antibodies to Yersinia outer membrane proteins (YOP) and changes in liveweight. RESULTS None of the six trial groups experienced an outbreak of clinical yersiniosis during the study period. On Farm A, the prevalence of shedding of either or both Yersinia spp. was <40% on all but one sampling occasions. On Farm B the prevalence of shedding of both Yersinia spp. peaked at 98%, 96 days after vaccination. Mean liveweight and daily liveweight gain at the end of the study were similar in vaccinated and non-vaccinated groups on both farms (p>0.1), as was the prevalence of faecal shedding of Yersinia spp. (p>0.2), and the proportion of animals that became seropositive for antibodies to YOP following vaccination (p>0.1). CONCLUSIONS AND CLINICAL RELEVANCE This vaccine had, at most, limited effects on seroconversion and, under the conditions of this study, had no demonstrable impact on liveweight, mean daily liveweight gain or faecal shedding of Yersinia spp. Further studies are needed to determine the efficacy of this vaccine during outbreaks of yersiniosis or following experimental challenge with pathogenic Yersinia spp..

Chlortetracycline Enhances Tonsil Colonization and Fecal Shedding of Multidrug-Resistant Salmonella enterica Serovar Typhimurium DT104 without Major Alterations to the Porcine Tonsillar and Intestinal Microbiota.

Salmonella spp. are estimated to cause 1.2 million cases of human foodborne illness each year in the United States, and pigs can often be asymptomatically colonized with Salmonella spp. (>50% of farms). Recent reports state that 18.3% of Salmonella enterica serovar Typhimurium isolates are resistant to ≥3 antimicrobial classes, and multidrug-resistant (MDR) strains are associated with an increased hospitalization rate and other complications. Chlortetracycline is commonly used in swine production to prevent/treat various diseases; therefore, chlortetracycline treatment of pigs unknowingly colonized with MDR Salmonella may have collateral effects on Salmonella spp. (and other gut bacteria). In this study, we determined the effect of in-feed chlortetracycline (400 g/ton) on shedding and colonization of pigs challenged with the MDR S Typhimurium strain DT104 (n = 11/group). We also assessed the impact on the fecal microbiota over the 12-day experimental period and on the ileum, cecum, and tonsil microbiota at 7 days postinoculation (dpi). In MDR S Typhimurium-inoculated pigs, chlortetracycline administration significantly increased fecal shedding at 2 dpi (+1.4 log10 CFU/g; P < 0.001) and enhanced tonsil colonization (+3.1 log10 CFU/g; P < 0.001). There were few major alterations detected in the gut or tonsillar microbiota of pigs treated with MDR S Typhimurium and/or chlortetracycline. The tonsillar transcriptome was largely unaffected despite increased colonization by MDR S Typhimurium following inoculation of the chlortetracycline-treated pigs. These results highlight the idea that chlortetracycline administration can enhance shedding and colonization of MDR S Typhimurium in pigs, which could increase the risk of environmental dissemination of MDR Salmonella strains.IMPORTANCESalmonella spp. are an important cause of foodborne illness in North America, and pork products are associated with sporadic cases and outbreaks of human salmonellosis. Isolates of Salmonella may be resistant to multiple antibiotics, and infections with multidrug-resistant (MDR) Salmonella spp. are more difficult to treat, leading to increased hospitalization rates. Swine operations commonly use antimicrobials, such as chlortetracycline, to prevent/treat infections, which may have collateral effects on pig microbial populations. Recently, we demonstrated that chlortetracycline induces the expression of genes associated with pathogenesis and invasion in MDR Salmonella enterica serovar Typhimurium in vitro In our current study, we show increased tonsillar colonization and fecal shedding of the MDR S Typhimurium strain DT104 from pigs administered chlortetracycline. Therefore, pigs unknowingly colonized with multidrug-resistant Salmonella spp. and receiving chlortetracycline for an unrelated infection may be at a greater risk for disseminating MDR Salmonella spp. to other pigs and to humans through environmental or pork product contamination.

Influence of a specific amino acid pattern in the diet on the course of an experimental Campylobacter jejuni infection in broilers.

Campylobacter jejuni (C. jejuni) is one of the most important zoonotic pathogens worldwide. In Europe, the majority of the cases are caused by consuming contaminated poultry meat. The objective of the present study was to investigate potential effects of different crude protein levels in complete diets for broilers on infection dynamics of C. jejuni after experimental infection. In total, 300 commercial broilers line Ross 308 were divided into 4 different groups, including 5 replications of 15 chickens each. The chickens were fed a conventional diet (212 g CP/kg DM) and a protein-reduced test diet (190 g CP/kg DM) supplemented with essential amino acids. This resulted simultaneously in lower amino-acid concentrations preferentially utilized by C. jejuni, such as aspartate, glutamate, proline, and serine. One group of each feeding concept was infected artificially with C. jejuni at day 21 by applying an oral C. jejuni inoculum containing 4.17 ± 0.09 log10 cfu of C. jejuni to 3 of 15 chickens, called "seeders." Feeding the test diet resulted in a significant reduction (P < 0.001) in CP intake (31.5 ± 1.20 g CP/broiler/day and 27.7 ± 0.71 g CP/broiler/day, respectively), a significant decrease (P < 0.05) in crude mucin in excreta (55.7 ± 8.23 g/kg DM and 51.9 ± 7.62 g/kg DM, respectively), and in goblet cell number in cecal crypts (P < 0.05; 15.1 ± 5.71 vs. 13.6 ± 5.91 goblet cells/crypt). In groups receiving the test diet, the excretion of C. jejuni was significantly reduced in seeders by 1.9 log10 cfu/g excreta at day 23 (3.38a ± 2.55 vs. 1.47b ± 2.20; P = 0.033). At day 25, prevalence of C. jejuni in cloacal swabs amounted to 53.3% in the group fed the test diet and 75.7% in the control group, respectively (P < 0.05). In summary, a definite amino acid pattern in the broiler diets could contribute to a development of an effective feeding strategy to reduce the prevalence of C. jejuni infection in chickens (Patent No 17187659.2-1106).

The synergistic effect of organic acids, phytochemicals and a permeabilizing complex reduces Salmonella Typhimurium 1,4,[5],12:i-shedding in pigs.

Salmonella Typhimurium (including S.Typhimurium 1,4,[5],12:i-) and other enteric pathogens cause acute infection in pigs during the weaning stage, often evolving into chronic infections responsible for the introduction of zoonotic bacteria into the slaughterhouse and thus determining carcass contamination. In addition to being zoonotic hazards, these pathogens are responsible for economic losses in affected farms. Traditionally, antibiotic treatments have been largely administered in order to reduce the infection burden but it favored, as a direct consequence, an increase in the number of multi-drug resistance strains. In order to overcome antibiotic-resistance concerns, new alternative control strategies should be developed. In this context, a blend of organic acids, phytochemicals and a permeabilizing complex, administered in feed (Group A - 459 piglets) or water (Group B - 458 piglets), was tested in field conditions for its capability of reducing Salmonella-infection in weaned piglets of an endemic farm. Data recorded were compared to results of a control group (Group C - 456 piglets). Zootechnical parameters were recorded in all animals, while microbiological, serological and PCR analyses were conducted in 15 piglets for each group. Results demonstrated that additive administered in feed improved animal weight gain (better average daily gain [A.D.G.] and increment), and rapidly reduced Salmonella-shedding in feces. Administration of additive in feed gave better results than in water.

Vaccination Against Lawsonia intracellularis Decreases Shedding of Salmonella enterica serovar Typhimurium in Co-Infected Pigs and Alters the Gut Microbiome.

Salmonella enterica serovar Typhimurium continues to be a major cause of foodborne illness worldwide and pork can serve as a source of infection. Co-infection of S. enterica with Lawsonia intracellularis, a common intestinal pathogen of swine, has been found as risk factor for increased S. enterica shedding. The objective of this study was to investigate if vaccination against L. intracellularis could lead to decreased S. Typhimurium shedding. To test this hypothesis, pigs were challenged with either S. Typhimurium or S. Typhimurium and L. intracellularis, with and without L. intracellularis vaccination (n = 9 per group). A non-challenged group served as a negative control. Vaccination decreased the shedding of S. Typhimurium in co-infected animals by 2.12 log10 organisms per gram of feces at 7 days post infection. Analysis of the microbiome showed that vaccination led to changes in the abundance of Clostridium species, including Clostridium butyricum, in addition to other compositional changes that may explain the protection mediated against S. Typhimurium. These results indicate that vaccination against L. intracellularis in co-infected herds may provide a new tool to increase food safety by helping to prevent S. enterica without the need for antibiotics.

Pilot studies of a human BCG challenge model.

Despite the great effort to develop an effective vaccine against tuberculosis (TB) there is currently no reliable and safe human challenge model that can be used for in vivo evaluation of new TB vaccine candidates and/or elucidation of the mechanisms of TB protective immunity. In this study, five volunteers were challenged with BCG intradermally (ID). Swab specimens were collected at multiple time points from the vaccination site pre- and post-vaccination to quantitate mycobacterial shedding as a surrogate of in vivo mycobacterial immunity. We compared the performance of the TaqMan qPCR assay against colony-forming unit cultures on 7H10 agar plates, and time to positivity (TTP) of mycobacterial growth indicator tubes (MGIT) in order to evaluate the reproducibility and sensitivity in measuring BCG burden in swab specimens. BCG was detected in swab specimens from all five volunteers by at least one method, and no single method was superior in terms of sensitivity and reproducibility. A comparison of all three methods showed significant correlations by Spearman's rank test between 7H10 agar plating and qPCR (R = 0.601, P = 0.00072), MGIT culture TTP and 7H10 agar plating (R = 0.412, P = 0.029) as well as MGIT culture TTP and qPCR (R = -0.708, P = 0.00003). However, the three methods were somewhat different with regard to early versus late detection of BCG shedding post-challenge. This ID BCG challenge model has unique potential to further explore correlations between reactogenicity and immune mechanisms involved in protection against mycobacterial infections, and could therefore become a reliable tool in the evaluation process of new TB vaccination strategies.

Investigation of in-feed organic acids as a low cost strategy to combat Salmonella in grower pigs.

Salmonella carriage in pigs is a significant food safety issue. Dietary supplementation with organic acids has previously been shown to reduce shedding and transmission of Salmonella. Therefore, this study aimed to examine the effect of three commercially available organic acid-based products on Salmonella levels in grower pigs, using a model of experimental infection that closely mimics natural exposure to the organism. Seven week old trial pigs (n=40) with a mean weight of 14.7kg were placed in one of four pens with 10 pigs/pen. Pens had previously been contaminated with Salmonella Typhimurium 4,[5],12;i;- via seeder pigs. Trial pigs received one of four diets for 28days: 1, control diet; 2, sodium butyrate supplemented diet; 3, benzoic acid supplemented diet and 4, formic-citric acid supplemented diet. A further 10 pigs were placed in a Salmonella-free pen receiving the control diet. Pigs were weighed and blood sampled on days 0 and 28. Faeces was collected on day 0, 2, 3, 5, 7, 14, 21 and 28 and examined for Salmonella. On day 28, 5 pigs/group were euthanised and ileocaecal lymph nodes (ILN) and caecal contents sampled for culture. The remaining 5 pigs/pen were then fed the control diet and faeces were collected on days 35 and 42. On day 42 pigs were euthanised and ILN and caecal contents tested for Salmonella levels. The trial was repeated once. Within the first two days of exposure to the contaminated environment, 96% (77/80) of pigs became infected. Most pigs shed Salmonella at levels of between 100-103 CFU/g faeces for at least 7days post-exposure. A significant reduction in Salmonella faecal concentration was observed after supplementation with sodium butyrate (p=0.001) and a formic citric acid blend (p<0.0001). Average daily weight gain (ADWG) was significantly increased in all groups fed the supplemented feed when compared to the positive control group. The use of sodium butyrate or a blend of formic and citric acid in feed could be considered a cost-effective control measure to reduce Salmonella faecal shedding and improve ADWG in Salmonella infected herds.

In vivo therapeutic efficacy and pharmacokinetics of colistin sulfate in an experimental model of enterotoxigenic Escherichia coli infection in weaned pigs.

Enterotoxigenic Escherichia coli (ETEC: F4) associated with post-weaning diarrhea (PWD) in pigs has developed resistance against several antimicrobial families, leading to increased use of colistin sulfate (CS) for the treatment of this disease. The objective of this study was to determine the efficacy of oral CS treatment in experimental PWD due to ETEC: F4 challenge and determine the effect of this challenge on CS intestinal absorption. In this study, 96 pigs were divided into two trials based on CS dose (100 000 or 50 000 IU/kg). Fecal shedding of ETEC: F4, total E. coli, and CS-resistant E. coli, diarrhea scores, and weight changes were evaluated. Colistin sulfate plasma concentrations were determined by HPLC-MS/MS. Regardless of the dose, CS treatment resulted in a reduction of fecal ETEC: F4 and total E. coli shedding, and in diarrhea scores but only during the treatment period. However, CS treatment resulted in a slight increase in fecal shedding of CS resistant E. coli and did not prevent weight loss in challenged pigs. In addition, challenge with ETEC: F4 resulted in an increase of CS intestinal absorption. Our study is among the first to demonstrate that under controlled conditions, CS was effective in reducing fecal shedding of ETEC: F4 and total E. coli in experimental PWD. However, CS treatment was associated with a slight selection pressure on E. coli and did not prevent pig weight loss. Further studies are needed in field conditions, to better characterize CS therapeutic regimen efficacy and bacterial resistance dissemination.

Feeding wet distillers grains plus solubles with and without a direct-fed microbial to determine performance, carcass characteristics, and fecal shedding of O157:H7 in feedlot heifers.

The inclusion of wet distillers grains plus solubles (WDGS) in feedlot diets has become a common practice in many regions of the United States due to the expanded production of byproducts and fluctuating corn prices related to ethanol production and other factors. In addition, societal concerns over the continued use of antimicrobials in agriculture production combined with an enhanced interest in disease and pathogen prevention in the food supply have led to an increased interest in use of direct-fed microbials (DFM) in growing and finishing cattle. Direct-fed microbials have been shown to improve ADG and feed efficiency, alter ruminal fermentation, and decrease fecal shedding of potential harmful pathogens in feedlot cattle in some experiments. The objective of this experiment was to evaluate the effects of WDGS inclusion with or without a DFM containing (1 × 10 cfu ∙ heifer ∙ d) combined with (1 × 10 cfu ∙ heifer ∙ d) on the performance, carcass characteristics, and O157:H7 shedding in feedlot heifers. In early August, 288 crossbred heifers (initial BW = 295 ± 28 kg) were assigned to 1 of 4 treatments (12 pens per treatment; 6 heifers per pen) in a randomized complete block design with a 2 × 2 factorial arrangement of treatments. Body weights and fecal grab samples were obtained at approximately 28-d intervals throughout the experiment. Across the feeding period, heifers fed 30% WDGS tended ( = 0.09) to have greater ADG and had greater carcass-adjusted ADG ( = 0.05) compared with heifers fed dry-rolled corn (DRC). Dry matter intake was not affected ( = 0.65) by diet, although carcass-adjusted G:F tended ( = 0.10) to be improved for heifers fed WDGS. Heifers fed 30% WDGS tended ( ≤ 0.10) to have greater fat thickness at the 12th rib, lower marbling scores, and higher yield grades. The inclusion of . combined with . in the diet had no effect ( > 0.10) on performance or carcass merit in the present experiment. The incidence of O157:H7 throughout the experiment was low, with only 18 positive samples across all sampling periods. Neither WDGS inclusion nor the inclusion of . combined with . in the diet had any effect ( > 0.10) on O157:H7 shedding in this experiment. Feeding 30% WDGS to feedlot heifers improved animal performance compared to the DRC-based control diet.

A randomised clinical trial on the efficacy of oxytetracycline dose through water medication of nursery pigs on diarrhoea, faecal shedding of Lawsonia intracellularis and average daily weight gain.

Oral treatment with antimicrobials is widely used in pig production for the control of gastrointestinal infections. Lawsonia intracellularis (LI) causes enteritis in pigs older than six weeks of age and is commonly treated with antimicrobials. The objective of this study was to evaluate the efficacy of three oral dosage regimens (5, 10 and 20mg/kg body weight) of oxytetracycline (OTC) in drinking water over a five-day period on diarrhoea, faecal shedding of LI and average daily weight gain (ADG). A randomised clinical trial was carried out in four Danish pig herds. In total, 539 animals from 37 batches of nursery pigs were included in the study. The dosage regimens were randomly allocated to each batch and initiated at presence of assumed LI-related diarrhoea. In general, all OTC doses used for the treatment of LI infection resulted in reduced diarrhoea and LI shedding after treatment. Treatment with a low dose of 5mg/kg OTC per kg body weight, however, tended to cause more watery faeces and resulted in higher odds of pigs shedding LI above detection level when compared to medium and high doses (with odds ratios of 5.5 and 8.4, respectively). No association was found between the dose of OTC and the ADG. In conclusion, a dose of 5mg OTC per kg body weight was adequate for reducing the high-level LI shedding associated with enteropathy, but a dose of 10mg OTC per kg body weight was necessary to obtain a maximum reduction in LI shedding.

Supplementation with Quaternary Benzo(c)phenanthridine Alkaloids Decreased Salivary Cortisol and Salmonella Shedding in Pigs After Transportation to the Slaughterhouse.

The present study was aimed at evaluating the effect of herbal extracts supplementation, particularly quaternary-benzo(c)phenanthridine alkaloids (QBA), which have been previously demonstrated to have anti-inflammatory, antimicrobial, and immune-modulator effects. We investigated the role of QBA on stress response and Salmonella shedding in finishing pigs transported to the slaughterhouse. A total of 82 pigs were orally challenged with a Salmonella cocktail (day 0) containing Salmonella Meleagridis, Hartford, Bovismorbificans and Newport serovars and randomly assigned to three treatment groups after 2 wks (day [D] 14): T1, in-feed QBA; T2, in-feed and water-soluble QBA; CON, nonsupplemented). Pigs were transported to the slaughterhouse 2 weeks after intervention (D 28) and slaughtered after nearly 19 h (D 29). Saliva, fecal samples, and carcass swabs were collected from all pigs. Salivary cortisol, Salmonella shedding, and carcass contamination were measured. A high positive correlation (Spearman rank correlation coefficient range 0.82-0.93) between salivary cortisol and Salmonella shedding was found after transportation in all groups (p < 0.05). Only the CON group showed an increase in salivary cortisol after transportation (5.48 ng/mL; p < 0.0001) to concentrations that were higher than in T1 (2.73 ng/mL; p = 0.0002) and T2 (1.88 ng/mL; p < 0.0001). Salmonella prevalence and shedding decreased after transportation in pigs receiving the QBA intervention (p < 0.05), whereas the control group showed a significant increase in Salmonella shedding after transportation (p = 0.04). At D 28, pigs in T2 shed lower numbers of Salmonella as compared to T1 (1.3E + 02 CFU/mL versus 8E + 03 CFU/mL; p = 0.002). Additionally, carcass contamination by Salmonella was higher in the CON group than the treated groups (p = 0.01). The findings show QBA intervention was effective in reducing transportation stress of pigs, resulting in reduced Salmonella shedding and positively impacting animal welfare and pork safety.