Browsing by Author "Kelly, Carmel A."
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ItemThe effect of natural antimicrobials against Campylobacter spp. and its similarities to Salmonella spp, Listeria spp., Escherichia coli, Vibrio spp., Clostridium spp. and Staphylococcus spp.(Elsevier, 2020-11-13) Balta, Igori; Linton, W. Mark R.; Pinkerton, Laurette; Kelly, Carmel A.; Stef, Lavinia; Pet, Ioan; Stef, Ducu; Criste, Adriana; Gundogdu, Ozan; Corcionivoschi, NicolaeThe increased resistance of campylobacters to antibiotics required the identification and isolation of novel antimicrobials able to inhibit its virulence, to cause less or no resistance and display no host toxicity. Acquiring all this knowledge was only possible through a better understanding of their antibacterial potency and of the biological mechanisms involved attenuating the bacterial virulence factors. This review describes the most recent developments in the area by looking at the new antimicrobial interventions aiming to combat the transmission and colonisation of Campylobacter spp. and its commonalities with other pathogenic bacteria. In this review we are also looking into the most recent developments, both in vitro and in vivo, focusing on the biological mechanisms by which natural antimicrobials express their anti-pathogenic effect. Following this extensive literature search we conclude that further studies are essential to elucidate the efficiency of plant, animal, bacteria and marine-derived antimicrobials as well as their role as promising alternatives to antibiotics. ItemImpact of industrial production system parameters on chicken microbiomes: mechanisms to improve performance and reduce Campylobacter(BMC, 2020-09-09) McKenna, Aaron; Ijaz, Umer Zeeshan; Kelly, Carmel A.; Linton, W. Mark R.; Sloan, William T.; Green, Brian D.; Lavery, Ursula; Dorrell, Nick; Wren, Brendan W.; Richmond, Anne; Corcionivoschi, Nicolae; Gundogdu, OzanBackground The factors affecting host-pathogen ecology in terms of the microbiome remain poorly studied. Chickens are a key source of protein with gut health heavily dependent on the complex microbiome which has key roles in nutrient assimilation and vitamin and amino acid biosynthesis. The chicken gut microbiome may be influenced by extrinsic production system parameters such as Placement Birds/m2 (stocking density), feed type and additives. Such parameters, in addition to on-farm biosecurity may influence performance and also pathogenic bacterial numbers such as Campylobacter. In this study, three different production systems ‘Normal’ (N), ‘Higher Welfare’ (HW) and ‘Omega-3 Higher Welfare’ (O) were investigated in an industrial farm environment at day 7 and day 30 with a range of extrinsic parameters correlating performance with microbial dynamics and Campylobacter presence. Results Our data identified production system N as significantly dissimilar from production systems HW and O when comparing the prevalence of genera. An increase in Placement Birds/m2 density led to a decrease in environmental pressure influencing the microbial community structure. Prevalence of genera, such as Eisenbergiella within HW and O, and likewise Alistipes within N were representative. These genera have roles directly relating to energy metabolism, amino acid, nucleotide and short chain fatty acid (SCFA) utilisation. Thus, an association exists between consistent and differentiating parameters of the production systems that affect feed utilisation, leading to competitive exclusion of genera based on competition for nutrients and other factors. Campylobacter was identified within specific production system and presence was linked with the increased diversity and increased environmental pressure on microbial community structure. Addition of Omega-3 though did alter prevalence of specific genera, in our analysis did not differentiate itself from HW production system. However, Omega-3 was linked with a positive impact on weight gain. Conclusions Overall, our results show that microbial communities in different industrial production systems are deterministic in elucidating the underlying biological confounders, and these recommendations are transferable to farm practices and diet manipulation leading to improved performance and better intervention strategies against Campylobacter within the food chain. ItemThe In Vitro and In Vivo Effect of Carvacrol in Preventing Campylobacter Infection, Colonization and in Improving Productivity of Chicken Broilers(Mary Ann Liebert, Inc., 2017-06-01) Kelly, Carmel A.; Gundogdu, Ozan; Pircalabioru, Gratiela; Cean, Ada; Scates, Pamela J.; Linton, W. Mark R.; Pinkerton, Laurette; Magowan, Elizabeth; Staf, Lavinia; Simiz, Eliza; Pet, Ioan; Stewart, Sharon; Stabler, Richard; Wren, Brendan; Dorrell, Nick; Corcionivoschi, NicolaeThe current trend in reducing the antibiotic usage in animal production imposes urgency in the identification of novel biocides. The essential oil carvacrol, for example, changes the morphology of the cell and acts against a variety of targets within the bacterial membranes and cytoplasm, and our in vitro results show that it reduces adhesion and invasion of chicken intestinal primary cells and also biofilm formation. A trial was conducted to evaluate the effects of dietary supplementation of carvacrol at four concentrations (0, 120, 200, and 300 mg/kg of diet) on the performance of Lactobacillus spp., Escherichia coli, Campylobacter spp., and broilers. Each of the four diets was fed to three replicates/trial of 50 chicks each from day 0 to 35. Our results show that carvacrol linearly decreased feed intake, feed conversion rates and increased body weight at all levels of supplementation. Plate count analysis showed that Campylobacter spp. was only detected at 35 days in the treatment groups compared with the control group where the colonization occurred at 21 days. The absence of Campylobacter spp. at 21 days in the treatment groups was associated with a significant increase in the relative abundance of Lactobacillus spp. Also, carvacrol was demonstrated to have a significant effect on E. coli numbers in the cecum of the treatment groups, at all supplementation levels. In conclusion, this study shows for the first time that at different concentrations, carvacrol can delay Campylobacter spp., colonization of chicken broilers, by inducing changes in gut microflora, and it demonstrates promise as an alternative to the use of antibiotics. ItemMixtures of natural antimicrobials can reduce Campylobacter jejuni, Salmonella enterica and Clostridium perfringens infections and cellular inflammatory response in MDCK cells(Springer, 2021-06-07) Balta, Igori; Marcu, Adela; Linton, W. Mark R.; Kelly, Carmel A.; Gundogdu, Ozan; Stef, Lavinia; Pet, Ioan; Ward, Patrick; Deshales, Myriam; callaway, Todd; Sopharat, Phittawat; Gradisteanu-Pircalabioru, Gratiela; Corcionivoschi, NicolaeBackground: The classification of natural antimicrobials as potential antibiotic replacements is still hampered by the absence of clear biological mechanisms behind their mode of action. This study investigated the mechanisms underlying the anti-bacterial effect of a mixture of natural antimicrobials (maltodextrin, citric acid, sodium citrate, malic acid, citrus extract and olive extract) against Campylobacter jejuni RC039, Salmonella enterica SE 10/72 and Clostridium perfringens ATCC® 13124 invasion of Madin–Darby Canine Kidney cells (MDCK). Results: Minimum sub-inhibitory concentrations were determined for Campylobacter jejuni (0.25%), Salmonella enterica (0.50%) and Clostridium perfringens (0.50%) required for the in vitro infection assays with MDCK cells. The antimicrobial mixture significantly reduced the virulence of all three pathogens towards MDCK cells and restored the integrity of cellular tight junctions through increased transepithelial resistance (TEER) and higher expression levels of ZO-1 (zonula occludens 1) and occludin. This study also identified the ERK (external regulated kinase) signalling pathway as a key mechanism in blocking the pro-inflammatory cytokine production (IL-1β, IL-6, IL-8, TNF-α) in infected cells. The reduction in hydrogen peroxide ( H2O2) production and release by infected MDCK cells, in the presence of the antimicrobial mixture, was also associated with less tetrathionate formed by oxidation of thiosulphate (p < 0.0001). Conclusion: The present study describes for the first time that mixtures of natural antimicrobials can prevent the formation of substrates used by bacterial pathogens to grow and survive in anaerobic environments (e.g. tetrathionate).