ORCID Profile
0000-0002-1559-568X
Current Organisation
RMIT University
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Food Packaging, Preservation and Safety | Veterinary Microbiology (excl. Virology) | Animal Production | Animal Protection (Pests and Pathogens)
Poultry | Expanding Knowledge in the Agricultural and Veterinary Sciences | Veterinary Biological Preventatives (e.g. Vaccines) |
Publisher: Elsevier BV
Date: 03-2020
DOI: 10.1016/J.JGAR.2019.07.031
Abstract: Antibiotics are frequently used in food animal production in developing countries to promote the well-being and growth of animals. This practice provides some economic benefits to producers and consumers at large. Nevertheless, this practice is also associated with a number of concerns. A major concern has been that repeatedly exposing these animals to small doses of antibiotics contributes significantly to antimicrobial resistance, since a good fraction of the antibiotics used are the same or surrogates of antibiotics used in human therapeutic practices. Studies over decades have shown an explicit relationship between antimicrobial use and antimicrobial resistance in veterinary science. Many antibiotics can be purchased over the counter in African countries, and antibiotic resistance is an important issue to address in this region. This review examines some of the risks and benefits associated with antibiotic use in food animals. We conclude that the use of antibiotics in food animal production constitutes a major contributing factor to the current antimicrobial resistance crisis and that antibiotics should only be used for the treatment of sick animals based on prior diagnosis of disease.
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.IJFOODMICRO.2008.03.029
Abstract: This study was conducted to examine a current baseline profile of antimicrobial resistance and virulence of Escherichia coli isolated from foods commonly sold in the market place in Vietnam. E. coli were isolated from 180 s les of raw meat, poultry and shellfish and also isolated from 43 chicken faeces s les. Ninety-nine E. coli isolates recovered from all sources were selected for the investigation of their susceptibility to 15 antimicrobial agents by the disk diffusion method. Eighty-four percent of the isolates were resistant to one or more antibiotics, and multi-resistance, defined as resistance to at least 3 different classes of antibiotics, was detected in all sources. The rates of multi-resistance were up to 89.5% in chicken, 95% in chicken faeces and 75% in pork isolates. Resistance was most frequently observed to tetracycline (77.8%), sulfafurazole (60.6%), icillin (50.5%), amoxicillin (50.5%), trimethoprim (51.5%), chlor henicol (43.4%), streptomycin (39.4%), nalidixic acid (34.3%) and gentamicin (24.2%). In addition, the isolates also displayed resistance to fluoroquinolones (ciprofloxacin 16.2%, norfloxacin 17.2%, and enrofloxacin 21.2%), with chicken isolates showing the highest rates of resistance to these antibiotics (52.6-63.2%). Thirty-eight multi-resistant isolates were selected for further the examination of antibiotic resistance genes and were also evaluated for virulence gene profiles by multiplex and uniplex polymerase chain reaction. The beta-lactam TEM gene and tetracycline resistance tetA, tetB genes were frequently detected in the tested isolates (84.2% and 89.5% respectively). Genes which are responsible for resistance to streptomycin (aadA) (68.4%), chlor henicol (cmlA) (42.1%), sulfonamides (sulI) (39.5%), trimethoprim (dhfrV) (26.3%) and kanamycin (aphA-1) (23.7%) were also widely distributed. Plasmid-mediated C genes were detected in E. coli isolates from chicken and pork. The isolates were tested for the presence of 58 virulence genes for adhesins, toxins, capsule synthesis, siderophores, invasins and others from different E. coli pathotypes. All of the tested isolates contained at least one virulence gene and there were 16 genes detected. Virulence genes detected were fimH (92.1%), bmaE (84.2%), TSPE4.C2 (42.1%), aidA AIDA-I (orfB) (31.6%), east1 (26.3%), traT (23.7%), and others including fyuA, iutA, chuA, yjaA, iss, iroN(E. coli), ibeA, aah (orfA), iha and papG allele III (10.5-2.6%). Typical toxin genes produced by enterohemorrhagic and enterotoxigenic E. coli pathotypes (a heat-stable toxin (ST), heat-labile toxin (LT) and Shiga toxin stx1, stx2) were not detected in any of these 38 isolates. The study has revealed that E. coli in raw foods is a significant reservoir of resistance and virulence genes.
Publisher: Public Library of Science (PLoS)
Date: 23-03-2018
Publisher: Frontiers Media SA
Date: 28-10-2022
DOI: 10.3389/FVETS.2022.1039774
Abstract: Spotty Liver Disease (SLD) is a serious infectious disease which occurs mainly in laying chickens in free range production systems. SLD outbreaks can increase mortality and decrease egg production of chickens, adversely impact welfare and cause economic hardship for poultry producers. The bacterium C ylobacter hepaticus is the primary cause of the disease. This study aimed to identify the effects of C. hepaticus on chicken gut microbiota and gut structure. Three C. hepaticus strains (HV10 T , NSW44L and QLD19L), isolated from different states of Australia, were used in the study. Chickens at 26-weeks post-hatch were orally dosed with one of the C. hepaticus strains (challenged groups) or Brucella broth (unchallenged or control group). Six days after the challenge, birds were necropsied to assess liver damage, and caecal content and tissue s les were collected for histology, microbiology, and 16S rRNA gene licon sequencing to characterize the composition of the bacterial microbiota. Strain C. hepaticus NSW44L produced significantly more disease compared to the other C. hepaticus strains and this coincided with more adverse changes observed in the caecal microbiota of the birds challenged with this strain compared to the control group. Microbial ersity determined by Shannon and Simpson alpha ersity indices was lower in the NSW44L challenged groups compared to the control group ( p = 0.009 and 0.0233 respectively, at genus level). Short-chain fatty acids (SCFAs) producing bacteria Faecalibacterium, Bifidobacterium and Megamonas were significantly reduced in the challenged groups compared to the unchallenged control group. Although SLD-induction affected the gut microbiota of chickens, their small intestine morphology was not noticeably affected as there were no significant differences in the villus height or ratio of villus height and crypt depth. As gut health plays a pivotal role in the overall health and productivity of chickens, approaches to improve the gut health of the birds during SLD outbreaks such as through diet and keeping the causes of stress to a minimum, may represent significant ways to alleviate the impact of SLD.
Publisher: MDPI AG
Date: 10-09-2021
DOI: 10.3390/MICROORGANISMS9091927
Abstract: Vibriosis in farmed animals is a serious threat to aquaculture worldwide. Using probiotics and anti-Vibrio antimicrobial substances in aquaculture systems can be a means of preventing Vibrio infections. Therefore, we aimed to characterize and compare 16 potential anti-Vibrio probiotics (Vi+) isolated from marine sponges and fish intestines collected from the Vietnam Sea, as well as an anti-Vibrio bacteriocin to fully explore their application potentials. 16S rRNA sequencing confirmed all Vi+ to be Bacillus species with different strain variants across two s le types. An obvious antimicrobial spectrum toward Gram-negative bacteria was observed from intestinal Vi+ compared to sponge-associated Vi+. The reason was the higher gene frequency of two antimicrobial compounds, non-ribosomal peptides (NRPS) and polyketide type-I (PKS-I) from intestinal Vi+ (66.7%) than sponge-associated Vi+ (14.3% and 0%, respectively). Additionally, a three-step procedure was performed to purify an anti-Vibrio bacteriocin produced by B. methylotrophicus NTBD1, including (i) solvent extraction of bacteriocin from cells, (ii) hydrophobic interaction chromatography, and (iii) reverse-phase HPLC. The bacteriocin had a molecular weight of ~2–5 kDa, was sensitive to proteolysis and thermally stable, and showed a broad antimicrobial spectrum, all of which are essential properties for promising feed additives. This study provides necessary information of the potential of probiotic Bacillus species with anti-Vibrio antimicrobial properties to study their further use in sustainable aquaculture.
Publisher: Public Library of Science (PLoS)
Date: 05-08-2021
DOI: 10.1371/JOURNAL.PONE.0255633
Abstract: Traditional s ling methods for the study of poultry gut microbiota preclude longitudinal studies as they require euthanasia of birds for the collection of caecal and ileal contents. Some recent research has investigated alternative s ling methods to overcome this issue. The main goal of this study was to assess to what extent the microbial composition of non-invasive s les (excreta, litter and poultry dust) are representative of invasive s les (caecal and ileal contents). The microbiota of excreta, dust, litter, caecal and ileal contents (n = 110) was assessed using 16S ribosomal RNA gene licon sequencing. Of the operational taxonomic units (OTUs) detected in caecal contents, 99.7% were also detected in dust, 98.6% in litter and 100% in excreta. Of the OTUs detected in ileal contents, 99.8% were detected in dust, 99.3% in litter and 95.3% in excreta. Although the majority of the OTUs found in invasive s les were detected in non-invasive s les, the relative abundance of members of the microbial communities of these groups were different, as shown by beta ersity measures. Under the conditions of this study, correlation analysis showed that dust could be used as a proxy for ileal and caecal contents to detect the abundance of the phylum Firmicutes , and excreta as a proxy of caecal contents for the detection of Tenericutes . Similarly, litter could be used as a proxy for caecal contents to detect the abundance of Firmicutes and Tenericutes . However, none of the non-invasive s les could be used to infer the overall abundance of OTUs observed in invasive s les. In conclusion, non-invasive s les could be used to detect the presence and absence of the majority of the OTUs found in invasive s les, but could not accurately reflect the microbial community structure of invasive s les.
Publisher: Informa UK Limited
Date: 22-11-2020
Publisher: Springer Science and Business Media LLC
Date: 22-05-2018
Publisher: Inter-Research Science Center
Date: 02-07-2020
DOI: 10.3354/ESR01042
Abstract: The microbiota of metazoans can be influenced by a variety of factors including diet, environment and genetics. In this study we s led multiple populations from 2 host species that do not overlap in distribution, in order to test whether their bacterial microbiotas are species-specific or more variable. Intestinal swabs were collected from loggerhead turtles originating from Florida, USA, and Queensland, Australia, as well as from flatback turtles from Crab Island, Queensland, and Port Hedland, Western Australia. We then manually extracted bacterial DNA and used 16S rRNA sequencing to explore bacterial microbial community composition and structure. Our investigation showed that the bacterial microbiota of sea turtles is heavily influenced by geography, with loggerhead turtles originating from the USA and Australia harbouring significantly different bacterial microbial populations in terms of composition. Similarly, we also found that flatback turtles from Crab Island had significantly less erse microbiotas, with a predominance of the bacterial phylum Firmicutes , in comparison to their genetically similar counterparts from Port Hedland. Factors that may explain these observed differences between populations include host genetics, differences in foraging habitat quality and differences in migratory distance (and thus durations of inappetence) between foraging and breeding grounds. The mechanisms by which these factors may influence bacterial microbial composition of sea turtle gastrointestinal tracts warrants further investigation. The results of this study highlight the importance of interpreting microbiota data of wild animals in the context of geography.
Publisher: Elsevier BV
Date: 12-2019
Publisher: Microbiology Society
Date: 20-04-2022
Abstract: A novel species of C ylobacter was isolated from bile s les of chickens with spotty liver disease in Australia, making it the second novel species isolated from chickens with the disease, after C ylobacter hepaticus was isolated and described in 2016. Six independently derived isolates were obtained. They were Gram-stain-negative, microaerobic, catalase-positive, oxidase-positive and urease-negative. Unlike most other species of the genus C ylobacter , more than half of the tested strains of this novel species hydrolysed hippurate and most of them could not reduce nitrate. Distinct from C. hepaticus , many of the isolates were sensitive to 2,3,5-triphenyltetrazolium chloride (0.04%) and metronidazole (4 mg ml −1 ), and all strains were sensitive to nalidixic acid. Phylogenetic analysis using 16S rRNA and hsp60 gene sequences demonstrated that the strains formed a robust clade that was clearly distinct from recognized C ylobacter species. Whole genome sequence analysis of the strains showed that the average nucleotide identity and the genome blast distance phylogeny values compared to other C ylobacter species were less than 86 and 66%, respectively, which are below the cut-off values generally recognized for isolates of the same species. The genome of the novel species has a DNA G+C content of 30.6 mol%, while that of C. hepaticus is 27.9 mol%. Electron microscopy showed that the cells were spiral-shaped, with bipolar unsheathed flagella. The protein spectra generated from matrix-assisted laser desorption/ionization time of flight analysis demonstrated that they are different from the most closely related C ylobacter species. These data indicate that the isolates belong to a novel C ylobacter species, for which the name C ylobacter bilis sp. nov. is proposed. The type strain is VicNov18 T (=ATCC TSD-231 T =NCTC 14611 T ).
Publisher: Springer Science and Business Media LLC
Date: 02-10-2021
DOI: 10.1186/S42523-021-00127-Y
Abstract: A major focus of research on the gut microbiota of poultry has been to define signatures of a healthy gut and identify microbiota components that correlate with feed conversion. However, there is a high variation in in idual gut microbiota profiles and their association with performance. Population level s les such as dust and pooled excreta could be useful to investigate bacterial signatures associated with productivity at the flock-level. This study was designed to investigate the bacterial signatures of high and low-performing commercial meat chicken farms in dust and pooled excreta s les. Poultry house dust and fresh pooled excreta were collected at days 7, 14, 21, 28 and 35 of age from 8 farms of two Australian integrator companies and 389 s les assessed by 16S ribosomal RNA gene licon sequencing. The farms were ranked as low (n = 4) or high performers (n = 4) based on feed conversion rate corrected by body weight. Permutational analysis of variance based on Bray–Curtis dissimilarities using abundance data for bacterial community structure results showed that company explained the highest variation in the bacterial community structure in excreta (R 2 = 0.21, p = 0.001) while age explained the highest variation in the bacterial community structure in dust (R 2 = 0.13, p = 0.001). Farm performance explained the least variation in the bacterial community structure in both dust (R 2 = 0.03, p = 0.001) and excreta (R 2 = 0.01, p = 0.001) s les. However, specific bacterial taxa were found to be associated with high and low performance in both dust and excreta. The bacteria taxa associated with high-performing farms in dust or excreta found in this study were Enterococcus and Candidatus Arthromitus whereas bacterial taxa associated with low-performing farms included Nocardia , Lapillococcus , Brachybacterium , Ruania , Dietzia , Brevibacterium , Jeotgalicoccus, Corynebacterium and Aerococcus. Dust and excreta could be useful for investigating bacterial signatures associated with high and low performance in commercial poultry farms . Further studies on a larger number of farms are needed to determine if the bacterial signatures found in this study are reproducible.
Publisher: MDPI AG
Date: 10-11-2015
Publisher: Springer Science and Business Media LLC
Date: 21-10-2021
DOI: 10.1038/S41598-021-00277-8
Abstract: C ylobacter hepaticus causes Spotty Liver Disease (SLD) in chickens. C. hepaticus is fastidious and slow-growing, presenting difficulties when growing this bacterium for the preparation of bacterin vaccines and experimental disease challenge trials. This study applied genomic analysis and in vitro experiments to develop an enhanced C. hepaticus liquid culture method. In silico analysis of the anabolic pathways encoded by C. hepaticus revealed that the bacterium is unable to biosynthesise l- cysteine, l- lysine and l- arginine. It was found that l -cysteine added to Brucella broth, significantly enhanced the growth of C. hepaticus , but l- lysine or l- arginine addition did not enhance growth. Brucella broth supplemented with l- cysteine (0.4 mM), l- glutamine (4 mM), and sodium pyruvate (10 mM) gave high-density growth of C. hepaticus and resulted in an almost tenfold increase in culture density compared to the growth in Brucella broth alone (log10 = 9.3 vs 8.4 CFU/mL). The type of culture flask used also significantly affected C. hepaticus culture density. An SLD challenge trial demonstrated that C. hepaticus grown in the enhanced culture conditions retained full virulence. The enhanced liquid culture method developed in this study enables the efficient production of bacterial biomass and therefore facilitates further studies of SLD biology and vaccine development.
Publisher: Springer Science and Business Media LLC
Date: 20-05-2021
Publisher: Springer Science and Business Media LLC
Date: 09-05-2020
Publisher: Frontiers Media SA
Date: 21-12-2022
DOI: 10.3389/FVETS.2022.1082358
Abstract: C ylobacter hepaticus is the aetiological agent of Spotty Liver Disease (SLD). SLD can cause significant production loss and mortalities among layer hens at and around peak of lay. We previously developed an enzyme linked immunosorbent assay (ELISA), SLD-ELISA1, to detect C. hepaticus specific antibodies from bird sera using C. hepaticus total proteins and sera pre-absorbed with C ylobacter jejuni proteins. The high specificity achieved with SLD-ELISA1 indicated the presence of C. hepaticus specific antibodies in sera of infected birds. However, some of the reagents used in SLD-ELISA1 are time consuming to prepare and difficult to quality control. This understanding led to the search for C. hepaticus specific immunogenic proteins that could be used in recombinant forms as antibody capture antigens in immunoassay design. In this study, an immunoproteomic approach that combined bioinformatics analysis, western blotting, and LC MS/MS protein profiling was used, and a fragment of filamentous hemagglutinin adhesin (FHA), FHA 1,628−1,899 with C. hepaticus specific antigenicity was identified. Recombinant FHA 1,628−1,899 was used as antigen coating on ELISA plates to capture FHA 1,628−1,899 specific antibodies in sera of infected birds. SLD-ELISA2, based on the purified recombinant FHA fragment, is more user-friendly and standardizable than SLD-ELISA1 for screening antibody responses to C. hepaticus exposure in hens. This study is the first report of the use of FHA from a C ylobacter species in immunoassays, and it also opens future research directions to investigate the role of FHA in C. hepaticus pathogenesis and its effectiveness as a vaccine candidate.
Publisher: MDPI AG
Date: 24-02-2020
DOI: 10.3390/MICROORGANISMS8020309
Abstract: The Cedecea genus is comprised of six rarely isolated species within the Enterobacteriaceae family. Representatives are Gram-negative motile bacilli, and are typically oxidase-negative, lipase-positive and resistant to colistin and cephalothin. In this study, a putative novel Cedecea species (designated strain ZA_0188T), isolated from the koala hindgut, was characterised using a polyphasic taxonomic approach. Maximum average nucleotide identity (ANI) and 16S ribosomal RNA (rRNA) similarity scores well below thresholds of species demarcation were reported, at 81.1% and 97.9%, respectively. Multilocus phylogenetic analysis indicated strain ZA_0188T was most similar to but ergent from recognised Cedecea species. The isolate’s genomic G+C content was determined as 53.0 mol%, % lower than previously reported in Cedecea. Phenotypically, strain ZA_0188T was distinct from recognised Cedecea species such as colistin- and cephalothin-sensitive, lipase-, sorbitol-, sucrose-, and Voges-Proskauer-negative, and melibiose-, arabinose-, arginine-, and rhamnose-positive. In preliminary experiments, strain ZA_0188T exhibited cellulase activity and high-level tolerance to eucalyptus oil compared to other enteric species surveyed. Collectively, these findings suggest that strain ZA_0188T represents a novel enteric species, for which the name Cedecea colo is proposed.
Publisher: Springer Science and Business Media LLC
Date: 07-05-2020
DOI: 10.1186/S42523-020-00034-8
Abstract: The microbiota plays a critical role in host homeostasis and has been shown to be a major driving force in host evolution. However, our understanding of these important relationships is h ered by a lack of data for many species, and by significant gaps in s ling of the evolutionary tree. In this investigation we improve our understanding of the host-microbiome relationship by obtaining s les from all seven extant species of sea turtle, and correlate microbial compositions with host evolutionary history. Our analysis shows that the predominate phyla in the microbiota of nesting sea turtles was Proteobacteria. We also demonstrate a strong relationship between the bacterial phyla SR1 and sea turtle phylogeny, and that sea turtle microbiotas have changed very slowly over time in accordance with their similarly slow phenotypic changes. This is one of the most comprehensive microbiota studies to have been performed in a single clade of animals and further improves our knowledge of how microbial populations have influenced vertebrate evolution.
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.MICRES.2016.11.006
Abstract: According to the World Health Organisation, antibiotics are rapidly losing potency in every country of the world. Poultry are currently perceived as a major source of pathogens and antimicrobial resistance. There is an urgent need for new and natural ways to control pathogens in poultry and humans alike. Porous, cation rich, aluminosilicate minerals, zeolites can be used as a feed additive in poultry rations, demonstrating multiple productivity benefits. Next generation sequencing of the 16S rRNA marker gene was used to phylogenetically characterize the fecal microbiota and thus investigate the ability and dose dependency of zeolite in terms of anti-pathogenic effects. A natural zeolite was used as a feed additive in laying hens at 1, 2, and 4% w/w for a 23 week period. At the end of this period cloacal swabs were collected to s le faecal microbial communities. A significant reduction in carriage of bacteria within the phylum Proteobacteria, especially in members of the pathogen-rich family Enterobacteriaceae, was noted across all three concentrations of zeolite. Zeolite supplementation of feed resulted in a reduction in the carriage of a number of poultry pathogens without disturbing beneficial bacteria. This effect was, in some phylotypes, correlated with the zeolite concentration. This result is relevant to zeolite feeding in other animal production systems, and for human pathogenesis.
Publisher: Elsevier BV
Date: 03-2017
Publisher: MDPI AG
Date: 18-10-2022
DOI: 10.3390/ANTIBIOTICS11101428
Abstract: Poultry production is among the most challenging industries for pathogen control. High animal density and abundance of faecal material demand strict biosecurity measures and continual vigilance in monitoring animal health parameters. Despite this vigilance, dealing with disease outbreaks is a part of farmers’ routines. Phytogenic feed additives comprised of herbs, spices, essential oils, and oleoresins have potent antimicrobial and anti-inflammatory actions. Related studies are gaining substantial interest in human and animal health worldwide. In this study, a commercial blend phytogenic feed additive was supplemented to layers in an industrial free-range production system with 20,000 birds in both control and treatment groups. At the end of the trial, the ileum tissue was s led for RNAseq transcriptomic analysis to study the host reaction to the supplement. Phytogenic supplement significantly inhibited four cholesterol-related pathways and reduced the Arteriosclerosis disease category towards improved cardiovascular health. The supplemented birds exhibited reduced disease susceptibility for 26 cancer categories with p-values in the range from 5.23 × 10−4 to 1.02 × 10−25. Major metabolic shifts in Lipid metabolism in combination with Carbohydrate metabolism have resulted in a decrease in the Obesity category, altering the ratio of fat and carbohydrate metabolism toward lower fat storage.
Publisher: Microbiology Society
Date: 11-2016
Abstract: Ten strains of an unknown C ylobacter species were isolated from the livers of chickens with spotty liver disease in Australia. The strains were Gram-stain-negative, microaerobic, catalase- and oxidase-positive and urease-negative. Unlike most other species of the genus C ylobacter, most of the tested strains of this novel species hydrolysed hippurate and half of them could not reduce nitrate. All strains showed resistance, or intermediate resistance, to nalidixic acid and most of them were resistant to cephalothin. Examination of negatively stained cells under transmission electron microscopy revealed that they were S-shaped, with bipolar unsheathed flagella. Phylogenetic analyses based on the 16S rRNA gene and the heat shock protein 60 (hsp60) gene sequences indicated that the strains formed a robust clade that was clearly distinct from recognized C ylobacter species. Unusually, they had a DNA G+C content of 27.9 mol%, lower than any previously described C ylobacter species, and they showed less than 84 % average nucleotide identity to the nearest sequenced species. Taken together, these data indicate that the strains belong to a novel C ylobacter species, for which the name C ylobacter hepaticus sp. nov. is proposed. The type strain is HV10T (=NCTC 13823T=CIP 111092T).
Publisher: Springer Science and Business Media LLC
Date: 20-05-2020
DOI: 10.1038/S41598-020-65321-5
Abstract: The microbiota is considered critical for normal vertebrate homeostasis and it may exert its effects at a local level within the gastrointestinal tract, or systemically through the production of bacterial metabolites. To date, investigations into the role that the microbiota plays in reptile physiology are rare. To address this knowledge gap, we explored the relationship between differences in microbial communities to see if they accounted for differences in haematology and biochemistry values, in different populations of nesting flatback turtles ( Natator depressus ). We found that microbiota composition was not correlated to any of the blood analytes we measured in flatbacks. This study is the first of its kind in reptiles and highlights the need for further investigations to determine mechanisms by which the microbiota influences the physiology and health of reptiles.
Publisher: MDPI AG
Date: 17-11-2022
DOI: 10.3390/V14112543
Abstract: Spotty liver disease (SLD) causes substantial egg production losses and chicken mortality therefore, it is a disease that concerns Australian egg farmers. Over the last few decades, much research has been conducted to determine the etiologic agents of SLD and to develop potential therapeutics however, SLD still remains a major issue for the chicken industries globally and remained without the elucidation of potentially multiple pathogens involved. To help fill this gap, this study was aimed at understanding the viral ersity of bile s les from which the SLD-causing bacterium, C ylobacter hepaticus, has been isolated and characterised. The collected s les were processed and sequenced using high-throughput next-generation sequencing. Remarkably, this study found 15 galliform chaphamaparvoviruses (GaChPVs), of which 14 are novel under the genus Chaphamaparvovirus. Among them, nine were complete genomes that showed between 41.7% and 78.3% genome-wide pairwise similarities to one another. Subsequent phylogenetic analysis using the NS1 gene exhibited a multiple incursion of chaphamaparvovirus lineages, including a novel lineage of unknown ancestral history in free-range laying chickens in Australia. This is the first evidence of circulating many parvoviruses in chickens in Australia, which has increased our knowledge of the pathogen ersity that may have an association with SLD in chickens.
Publisher: Cold Spring Harbor Laboratory
Date: 11-04-2020
DOI: 10.1101/2020.04.10.035774
Abstract: Lactobacillus plantarum B21 isolated from Vietnamese sausage ( nem chua ) has previously displayed broad antimicrobial activity against gram positive bacteria including foodborne pathogens Listeria monocytogenes and Clostridium perfringens . This study successfully identified the antimicrobial agent as plantacyclin B21AG, a 5668 Da circular bacteriocin demonstrating high thermostability, resistance to a wide range of pH, proteolytic resistance and temporal stability. We report a reverse genetics approach used to identify and characterise plantacyclin B21AG. The bacteriocin was purified from culture supernatant by a short process consisting of concentration, n-butanol extraction and cation exchange chromatography. A de novo peptide sequencing using LC-MS/MS techniques identified two putative peptide fragments which were mapped to the genome of Lactobacillus plantarum B21. This revealed an ORF corresponding to a putative circular bacteriocin with a 33-amino acid leader peptide and 58-amino acid mature peptide found on native plasmid pB21AG01. The corresponding gene cluster, consisted of seven genes associated with post-translational circularisation, immunity and secretion. The robust nature of plantacyclin B21AG, its antimicrobial activity and associated machinery for cyclisation make it an interesting biotechnological target for further development, and application as a food-safe antimicrobial.
Publisher: Springer Science and Business Media LLC
Date: 05-01-2023
DOI: 10.1038/S41598-022-26532-0
Abstract: C ylobacter hepaticus is an important pathogen which causes Spotty Liver Disease (SLD) in layer chickens. SLD results in an increase in mortality and a significant decrease in egg production and therefore is an important economic concern of the global poultry industry. The human pathogen C ylobacter jejuni encodes an N -linked glycosylation system that plays fundamental roles in host colonization and pathogenicity. While N -linked glycosylation has been extensively studied in C. jejuni and is now known to occur in a range of C ylobacter species, little is known about C. hepaticus glycosylation. In this study glycoproteomic analysis was used to confirm the functionality of the C. hepaticus N- glycosylation system. It was shown that C. hepaticus HV10 T modifies 35 proteins with an N -linked heptasaccharide glycan. C. hepaticus shares highly conserved glycoproteins with C. jejuni that are involved in host colonisation and also possesses unique glycoproteins which may contribute to its ability to survive in challenging host environments. C. hepaticus N- glycosylation may function as an important virulence factor, providing an opportunity to investigate and develop a better understanding the system’s role in poultry infection.
Publisher: Springer Science and Business Media LLC
Date: 19-10-2019
DOI: 10.1007/S00253-019-10143-3
Abstract: The Australian saltwater crocodile (Crocodylus porosus) industry began commercially in the 1980s, producing skins for export and crocodile meat as a by-product. Industry research has thus far focused on strategies to improve production efficiency. In the current study, we utilised 16S rRNA sequencing to characterise the intestinal microbiome of Australian saltwater crocodiles. S les were collected from 13 commercially farmed crocodiles from six s le sites along the length of the intestinal tract. The results indicate a similar microbiome composition to that found in the freshwater alligator, with the dominate phyla represented by Firmicutes, primarily Clostridia, and Fusobacteria, which appears to be distinct from mammalian, fish, and other reptile phyla which are generally dominated by Firmicutes and Bacteroidetes. The high abundance of 'pathogenic' bacteria, with no apparent consequence to the host's health, is of great interest and warrants further additional investigation. This will enable expansion of the current understanding of host immune function and how it is modified by host and intestinal microbiome interactions.
Publisher: Informa UK Limited
Date: 23-09-2020
Publisher: Public Library of Science (PLoS)
Date: 26-04-2016
Publisher: Frontiers Media SA
Date: 07-05-2018
Publisher: Elsevier BV
Date: 10-2019
Publisher: Oxford University Press (OUP)
Date: 11-08-2020
DOI: 10.1093/JNCI/DJAA114
Abstract: ASPirin in Reducing Events in the Elderly, a randomized, double-blind, placebo-controlled trial of daily low-dose aspirin (100 mg) in older adults, showed an increase in all-cause mortality, primarily due to cancer. In contrast, prior randomized controlled trials, mainly involving younger in iduals, demonstrated a delayed cancer benefit with aspirin. We now report a detailed analysis of cancer incidence and mortality. 19 114 Australian and US community-dwelling participants aged 70 years and older (US minorities 65 years and older) without cardiovascular disease, dementia, or physical disability were randomly assigned and followed for a median of 4.7 years. Fatal and nonfatal cancer events, a prespecified secondary endpoint, were adjudicated based on clinical records. 981 cancer events occurred in the aspirin and 952 in the placebo groups. There was no statistically significant difference between groups for all incident cancers (hazard ratio [HR] = 1.04, 95% confidence interval [CI] = 0.95 to 1.14), hematological cancer (HR = 0.98, 95% CI = 0.73 to 1.30), or all solid cancers (HR = 1.05, 95% CI = 0.95 to 1.15), including by specific tumor type. However, aspirin was associated with an increased risk of incident cancer that had metastasized (HR = 1.19, 95% CI = 1.00 to 1.43) or was stage 4 at diagnosis (HR = 1.22, 95% CI = 1.02 to 1.45), and with higher risk of death for cancers that presented at stages 3 (HR = 2.11, 95% CI = 1.03 to 4.33) or 4 (HR = 1.31, 95% CI = 1.04 to 1.64). In older adults, aspirin treatment had an adverse effect on later stages of cancer evolution. These findings suggest that in older persons, aspirin may accelerate the progression of cancer and, thus, suggest caution with its use in this age group.
Publisher: Frontiers Media SA
Date: 14-11-2022
DOI: 10.3389/FVETS.2022.1058110
Abstract: Spotty liver disease (SLD) caused by C ylobacter hepaticus affects the health and productivity of layer hens and is a disease of concern in poultry. In this study, blood and cloacal swab s les were collected from 709 birds across 11 free-range layer farms from different regions of Australia. The prevalence of C. hepaticus specific antibodies and DNA was assessed using a C. hepaticus specific ELISA and PCR and its correlation with mortalities and changes in egg production was analyzed to better understand the seroprevalence of C. hepaticus in Australian free-range layer farms. C. hepaticus specific antibodies were detected from birds in four of the five farms that had no history of SLD with seroprevalence as high as 41% in one of the farms. Seroprevalence of anti- C. hepaticus antibodies among flocks that had an active or previous SLD outbreak varied between 2 and 64%. C. hepaticus DNA was detected from birds in three farms with no known SLD history and five farms with confirmed SLD outbreaks. A good correlation was observed between the ELISA and PCR results with a Pearson correlation coefficient value of 0.85 ( p -value = 0.001). No correlation was observed between the flock size or flock age and ELISA or PCR outcomes, and no significant difference between the seroprevalence of anti- C. hepaticus antibodies among flocks with or without a known history of SLD was established ( p = 0.143). This study demonstrates the usefulness of C. hepaticus specific ELISA and PCR in identifying the occurrence of mild or sub-clinical SLD and provides a broader and more complete understanding of SLD epidemiology that will inform future research aimed at the development of methods to control SLD, such as appropriate biosecurity measures, vaccines, and feed additives.
Publisher: Springer Science and Business Media LLC
Date: 15-08-2020
DOI: 10.1186/S13568-020-01077-5
Abstract: Microbial colonisation of the gastrointestinal tract of newly hatched chicks starts at hatch, seeded from the immediate hatching environment, and quickly results in dense colonisation. The role of ecological factors in gut colonisation has been extensively investigated, as well as the role of micro- and macronutrients in supporting and selecting for bacterial species highly adapted for utilising those nutrients. However, the microbial community contained in poultry feed and its influence on colonisation and maturation of gut microbiota has not been directly addressed. In this study, we compared the microbiota found in poultry feed, with the microbiota of ileum, cecum and excreta, to identify substantial overlap in core microbiotas of the compared groups. We then investigated the microbiota present in raw feedstuffs: meat and bone meal, wheat, corn, canola, barley, soybean, millrun, sorghum, poultry oil, oats, limestone and bloodmeal from four geographically distinct feedstuff suppliers. Each of the feedstuffs had erse microbial communities. The meat and bone meal and bloodmeal s les had the most complex and distinct microbial populations. There was substantial overlap in the phylogenetic composition found in the grain and seed s les: barley, canola, corn, millrun, oats, sorghum, soybean meal and wheat. Issues related to methodology, viability of microbial communities in the gut and feed, and the implications for biosecurity are discussed.
Publisher: Frontiers Media SA
Date: 05-02-2019
Publisher: Oxford University Press
Date: 22-03-2023
DOI: 10.1093/ACREFORE/9780190264093.013.1831
Abstract: Critical policy analysis has emerged as a prominent tradition of research in the field of education. Beginning in the 1980s in response to the failings of more traditional forms of policy analysis, this work typically examines the kinds of discourses and power relations that may be at play through the construction and function of policy. It is critical in orientation and interested in the social, cultural, and political context of policy as well as how analyzing policy may reveal opportunities for social change and reform. In contrast to traditional approaches which take policy problems as given, research in this tradition interrogates how discourse, language, and text set the context for how policy problems and solutions are conceptualized and how and why particular issues come to be framed as objects of concern. Critical policy analysis encompasses a range of different methodological approaches rather than a single method, with the approach taken dependent on the nature of the policy under analysis, the site of its production, the purpose of the research, and the positionality of the researcher. Four particularly prominent and generative approaches to critical policy analysis in educational research include (a) analysis of how policy is formed and operates across local and global contexts (b) the What’s the Problem Represented to Be? approach (c) research on networks and mobilities and (d) research drawing on Indigenous Critical Discourse Analysis. Each of these approaches offers insights for understanding problems of inequality and power in education and their origins and reproduction within and in relation to policy.
Publisher: Future Medicine Ltd
Date: 12-2014
DOI: 10.2217/FVL.14.93
Abstract: ABSTRACT The HA1 genes from influenza A strains A/Puerto Rico/8/1934 H1N1 (A/PR/8/34) and A/Hatay/2004 H5N1 were each cloned in Pichia pastoris vectors in the correct reading frame with the yeast α-factor secretion signal and the C-terminus His-tag, resulting in simple, fast purification of expressed H1HA1 and H5HA1 protein from the culture medium. Mice vaccinated with the purified proteins showed robust T cell, anti-HA1 IgG responses and developed a high antibody response for hemagglutination inhibition (HI) at titer 7.6 log 2 . Chickens vaccinated with a dose of 200 µg of H5HA1 mixed with either Montanide or Freund's adjuvants gave HI values of up to 7 log 2 at the third week comparable with a licensed inactivated H5N1 vaccine.
Publisher: Public Library of Science (PLoS)
Date: 12-08-2020
Publisher: Wiley
Date: 29-12-2014
DOI: 10.1111/PIM.12158
Abstract: Translationally controlled tumour protein (TCTP) may play an important role in the establishment or maintenance of parasitemia in a malarial infection. In this study, the potential of TCTP as a malaria vaccine was investigated in two trials. In the initial vaccine trial, Plasmodium falciparum TCTP (PfTCTP) was expressed in Saccharomyces cerevisiae and used to immunize BALB/c mice. Following challenge with Plasmodium yoelii YM, parasitemia was significantly reduced during the early stages of infection. In the second vaccine trial, the TCTP from P. yoelii and P. berghei was expressed in Escherichia coli and used in several mouse malaria models. A significant reduction in parasitemia in the early stages of infection was observed in BALB/c mice challenged with P. yoelii YM. A significantly reduced parasitemia at each day leading up to a delayed and reduced peak parasitemia was also observed in BALB/c mice challenged with the nonlethal Plasmodium chabaudi (P.c.) chabaudi AS. These results suggest that TCTP has an important role for parasite establishment and may be important for pathogenesis.
Publisher: Elsevier BV
Date: 2013
Publisher: Frontiers Media SA
Date: 22-12-2022
DOI: 10.3389/FVETS.2022.1058115
Abstract: Bacteriophages are viral predators of bacteria and are common in nature. Their host-specific infections against specific bacteria make them an attractive natural agent to control bacterial pathogens. Interest in the potential of bacteriophages as antibacterial agents in the production animal industries has increased. A total of 18 bacteriophages were isolated from Australian commercial poultry environments, from which three highly active phages were chosen for enrichment. Sequencing libraries were prepared using a Nextera XT kit (Illumina) and sequenced on an Illumina MiSeq instrument using 2 × 300 bp paired-end chemistry. The sequence data were then assembled and aligned with a2 bacteriophage as the reference. An animal trial was performed by oral gavaging Clostridium perfringens netB containing strain EHE-NE18 to the Ross 308 broiler chickens prior inoculation with Eimeria species. The chickens were raised following the management guide for Ross 308 from d 0 to d 21 and fed with starter and grower diets met the specific breed nutrient requirements. Body weight gain and feed intake were measured on d 9 and d 21 and FCR adjusted with mortality was calculated. The isolated bacteriophages only had only 96.7% similarity to the most closely related, previously characterized, Clostridium bacteriophage indicated that they might represent a novel strain of bacteriophage. A “cocktail” containing the three bacteriophages was capable of lysing four known disease-inducing C. perfringens strains in vitro . Oral administration of the bacteriophages cocktail to broilers challenged with necrotic enteritis markedly alleviated intestinal necrotic lesions in the duodenum and jejunum on day 16 post-hatch. The phage treatment significantly reduced the lesion scores of birds challenged with NE ( P & 0.01), and the lesion scores between birds treated with the bacteriophages and the unchallenged birds were not statistically different ( P & 0.05). However, no effect on the growth performance was observed during the recorded period of days 9-21. These findings suggest that bacteriophage treatment is a promising approach to protect intestinal health from C. perfringens induced necrotic enteritis. Further research will be required on the dosing, route of administration, and large scale validation studies to further advance this approach to pathogen control.
Publisher: Elsevier BV
Date: 2020
Publisher: Elsevier BV
Date: 2013
Publisher: American Society for Microbiology
Date: 30-04-2016
Abstract: Lactobacillus plantarum strain B21 was isolated from Vietnamese sausage (nem chua) and demonstrated broad antimicrobial activity due to the production of bacteriocins. Here, we report the complete genome sequence of this strain (3,284,260 bp).
Publisher: Informa UK Limited
Date: 12-04-2019
Publisher: Frontiers Media SA
Date: 15-01-2020
Publisher: MDPI AG
Date: 27-04-2020
DOI: 10.3390/MICROORGANISMS8050635
Abstract: Microbiota in the kangaroo gut degrade cellulose, contributing to the kangaroo’s energy and survival. In this preliminary study, to discover more about the gut microbes that contribute to the survival of kangaroos, cellulose-degrading bacteria were isolated from kangaroo scats by selection on solidified media containing carboxymethyl cellulose as the main carbon source. One frequently occurring aerobic bacterium was Siccibacter turicensis, a microbe previously isolated in fruit powder and from a patient with angular cheilitis. The whole genome sequence of the kangaroo isolate was obtained using the Illumina MiSeq platform. Its sequence shared 97.98% identity of the S. turicensis Type strain, and the ability of the Type strain to degrade cellulose was confirmed. Analysis of the genomic data focused on the cellulose operon. In addition to genes from the operon, we suggest that a gene following the operon may have an important role in regulating cellulose metabolism by signal transduction. This is the first report of S. turicensis found within microbiota of the animal gut. Because of its frequent presence in the kangaroo gut, we suggest that S. turicensis plays a role in cellulose digestion for kangaroos.
Publisher: American Society for Microbiology
Date: 11-2007
DOI: 10.1128/AEM.00972-07
Abstract: A study was conducted to examine the levels of Salmonella spp. contamination in raw food s les, including chicken, beef, pork, and shellfish, from Vietnam and to determine their antibiotic resistance characteristics. A total of 180 s les were collected and examined for the presence of Salmonella spp., yielding 91 Salmonella isolates. Sixty-one percent of meat and 18% of shellfish s les were contaminated with Salmonella spp. Susceptibility of all isolates to a variety of antimicrobial agents was tested, and resistance to tetracycline, icillin/amoxicillin, nalidixic acid, sulfafurazole, and streptomycin was found in 40.7%, 22.0%, 18.7%, 16.5%, and 14.3% of the isolates, respectively. Resistance to enrofloxacin, trimethoprim, chlor henicol, kanamycin, and gentamicin was also detected (8.8 to 2.2%). About half (50.5%) of the isolates were resistant to at least one antibiotic, and multiresistant Salmonella isolates, resistant to at least three different classes of antibiotics, were isolated from all food types. One isolate from chicken (serovar Albany) contained a variant of the Salmonella genomic island 1 antibiotic resistance gene cluster. The results show that antibiotic resistance in Salmonella spp. in raw food s les from Vietnam is significant.
Publisher: Elsevier BV
Date: 2023
DOI: 10.1016/J.VETMIC.2022.109603
Abstract: Spotty Liver Disease (SLD) is a significant disease of commercial layer hens. It can cause up to 10 % flock mortalities and reduce egg production by 25 %. C ylobacter hepaticus has been identified as the main cause of the disease, although it also appears that predisposing factors, such as some form of stress, may increase the likelihood of clinical disease occurring. Recently, a newly identified species, C ylobacter bilis, was isolated from bile s les of clinical SLD affected chickens. To investigate the pathogenic potential of C. bilis two independent isolates were used in infection trials of layer hens. Within 6 days of oral challenge birds developed typical SLD liver lesions, demonstrating that both strains induced SLD. C. bilis could be recovered from all the challenged birds that developed SLD. Thus, each of the steps in Koch's postulates have been fulfilled, confirming that C. bilis is an additional cause of SLD. A PCR method was developed which can specifically detect C. bilis from s les with complex microbiota. The identification of this newly discovered C ylobacter species as a second cause of SLD and the provision of a rapid method to detect the SLD causing bacterium will help with SLD vaccine development and epidemiology, thus assisting in the control of this important disease of poultry.
Publisher: Springer Science and Business Media LLC
Date: 17-12-2018
DOI: 10.1007/S00253-017-8688-4
Abstract: The poultry industry aims to improve productivity while maintaining the health and welfare of flocks. Pathogen control has been achieved through biosecurity, vaccinations and the use of antibiotics. However, the emergence of antibiotic resistance, in animal and human pathogens, has prompted researchers and chicken growers alike to seek alternative approaches. The use of new and emerging approaches to combat pathogen activity including nanotechnology, in particular, silver nanoparticles (NPs), has been found to not only eradicate pathogenic bacteria but also include issues of toxicity and bioaccumulation effects. Other novel metal nanoparticles could provide this pathogen reducing property with a more tailored and biocompatible nanomaterial for the model used, something our study represents. This study investigated the benefits of nanomaterial delivery mechanisms coupled with important health constituents using selenium as a biocompatible metal to minimise toxicity properties. Selenium NPs were compared to two common forms of bulk selenium macronutrients already used in the poultry industry. An intermediate concentration of selenium nanoparticles (0.9 mg/kg) demonstrated the best performance, improving the gut health by increasing the abundance of beneficial bacteria, such as Lactobacillus and Faecalibacterium, and short-chain fatty acids (SCFAs), in particular butyric acid. SCFAs are metabolites produced by the intestinal tract and are used as an energy source for colonic cells and other important bodily functions. Selenium nanoparticles had no significant effect on live weight gain or abundance of potentially pathogenic bacteria.
Publisher: Frontiers Media SA
Date: 23-02-2021
DOI: 10.3389/FIMMU.2021.619366
Abstract: Ulcerative colitis is an inflammatory disease of the colon that is associated with colonic neutrophil accumulation. Recent evidence indicates that diet alters the composition of the gut microbiota and influences host–pathogen interactions. Specifically, bacterial fermentation of dietary fiber produces metabolites called short-chain fatty acids (SCFAs), which have been shown to protect against various inflammatory diseases. However, the effect of fiber deficiency on the key initial steps of inflammation, such as leukocyte–endothelial cell interactions, is unknown. Moreover, the impact of fiber deficiency on neutrophil recruitment under basal conditions and during inflammation in vivo is unknown. Herein, we hypothesized that a fiber-deficient diet promotes an inflammatory state in the colon at baseline and predisposes the host to more severe colitis pathology. Mice fed a no-fiber diet for 14 days showed significant changes in the gut microbiota and exhibited increased neutrophil-endothelial interactions in the colonic microvasculature. Although mice fed a no-fiber diet alone did not have observable colitis-associated symptoms, these animals were highly susceptible to low dose (0.5%) dextran sodium sulphate (DSS)-induced model of colitis. Supplementation of the most abundant SCFA, acetate, prevented no-fiber diet-mediated enrichment of colonic neutrophils and colitis pathology. Therefore, dietary fiber, possibly through the actions of acetate, plays an important role in regulating neutrophil recruitment and host protection against inflammatory colonic damage in an experimental model of colitis.
Publisher: Elsevier BV
Date: 07-2014
DOI: 10.1016/J.VETMIC.2014.01.028
Abstract: A collection of 116 motile Pseudomonas spp. and 92 Aeromonas spp. isolated from 15 Vietnamese intensive catfish farms was analyzed to examine the molecular antibiotic resistance characteristics and the transferability of resistance markers within and between species. High levels of resistance to icillin, trimethoprim/sulfamethoxazole, nalidixic acid, chlor henicol, and nitrofurantoin were observed. The percentage of multiple drug resistance of Pseudomonas spp. and Aeromonas spp. isolates was 96.6% and 61.9%, respectively. The multiple antibiotic resistance (MAR) index mean values of 0.457 and 0.293 of Pseudomonas and Aeromonas isolates, respectively, indicated that these isolates were exposed to high risk sources of contamination where antibiotics were commonly used. Approximately 33% of Pseudomonas spp. and 28% of Aeromonas spp. isolates from catfish contained class 1 integrons, but no class 2 integrons were detected. Several common resistance genes including aadA, dfrA and catB were harbored in class 1 integrons. Large plasmids (>55 kb) were frequently detected in 50% and 71.4% of the plasmids extracted from Pseudomonas and Aeromonas isolates, respectively. Conjugation and transformation experiments demonstrated the successful transfer of all or part of the resistance phenotypes of catfish isolates to the recipient strains, including laboratory strains and strains isolated from this study. These results highlight the likely role of catfish bacteria as a reservoir of antibiotic resistant, Gram-negative bacteria harboring a pool of mobile genetic elements that can readily be transferred intra- and interspecies. To our knowledge, this is the first report on molecular characterization of antibiotic resistance of bacteria isolated from catfish in Vietnam.
Publisher: Public Library of Science (PLoS)
Date: 03-04-2019
Publisher: PeerJ
Date: 16-10-2020
DOI: 10.7717/PEERJ.10117
Abstract: The widespread occurrence of pathogenic bacteria resistant to last-line antibiotics has resulted in significant challenges in human and veterinary medicine. There is an urgent need for new antimicrobial agents that can be used to control these life threating pathogens. We report the identification of antimicrobial activities, against a broad range of bacterial pathogens, from a collection of marine-derived spore-forming bacteria. Although marine environments have been previously investigated as sources of novel antibiotics, studies on such environments are still limited and there remain opportunities for further discoveries and this study has used resources derived from an under-exploited region, the Vietnam Sea. Antimicrobial activity was assessed against a panel of Gram-positive and Gram-negative bacteria, including several multi-drug resistant pathogens. From a total of 489 isolates, 16.4% had antimicrobial activity. Of 23 shortlisted isolates with the greatest antimicrobial activity, 22 were Bacillus spp. isolates and one was a Paenibacillus polymyxa isolate. Most of the antimicrobial compounds were sensitive to proteases, indicating that they were proteins rather than secondary metabolites. The study demonstrated that marine bacteria derived from the Vietnam Sea represent a rich resource, producing antimicrobial compounds with activity against a broad range of clinically relevant bacterial pathogens, including important antibiotic resistant pathogens. Several isolates were identified that have particularly broad range activities and produce antimicrobial compounds that may have value for future drug development.
Publisher: Elsevier BV
Date: 03-2022
DOI: 10.1016/J.VETMIC.2022.109341
Abstract: C ylobacter hepaticus causes Spotty Liver Disease (SLD) in layer hens, resulting in mortality and productivity losses. Like other C ylobacter species, C. hepaticus is a fastidious organism that requires microaerobic conditions to grow and efficiently replicate. Despite its apparent vulnerability to environmental conditions, it is suspected that there are environmental sources of C. hepaticus that cause infections in chickens newly placed in production houses. Although C. hepaticus DNA has been detected in insects, rodent and wild bird droppings, and in environmental s les such as water and soil, it has not been possible to culture C. hepaticus from these sources. Therefore, it is unclear whether these environments harbor viable bacteria or the remnants of dead bacteria. Determining the viability of C. hepaticus in challenging conditions has implications for understanding the potential relevance of environmental reservoirs and routes of transmission. Other C ylobacters are known to enter viable but nonculturable (VBNC) states that result in prolonged survival in hostile environmental conditions. This study has demonstrated that C. hepaticus can also enter a VBNC state when stored in water or a simple salt solution (Ringer's solution). Cells in the VBNC state could not be recovered on media normally used for primary isolation, but media modifications were tested, and a 'resuscitation' media was developed. VBNC cells could be recovered from Ringer's solution stored at 4 °C for up to 112 days. VBNC cells are postulated to play an important role in the epidemiology of SLD.
Publisher: MDPI AG
Date: 25-11-2022
DOI: 10.3390/ANI12233296
Abstract: The concept of designer microbiota in chicken is focused on early exposure of the hatchlings to pathogen-free microbiota inoculum, limiting the early access to harmful and pathogenic microorganisms, thus promoting colonisation of the gut with beneficial and natural poultry microbiota. In this study, we controlled colonisation of the intestine in broiler chickens in a large-scale industrial setting via at-hatch administration of a commercial product containing a highly erse microbiota originating from the chicken caecum. The treatment significantly transformed the microbiota membership in the crop, proventriculus, jejunum and caecum and significantly altered the taxa abundance in the jejunum, jejunum mucosa, and caecum estimated using PERMANOVA and unweighted and weighted UniFrac distances, respectively. The treatment also improved the growth rate in chickens with no significant alteration in feed conversion ratio. A comparison of inoculum product microbiota structure revealed that the inoculum had the highest Shannon ersity index compared to all investigated gut sections, and the number of Observed Species second only to the caecal community. PCoA plots using weighted or unweighted UniFrac placed the inoculum s les together with the s les from the caecal origin.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/MA16037
Abstract: The fishery sector is an important source of income, employment and food supply in Vietnam. In 2014, Vietnam was ranked the world's fourth largest exporter and the third largest producer of farmed food fish. Vietnam seafood export has attained the value of over US$6.0 billion since 2011 and reached a peak of US$7.9 billion in 2014. However, many problems and diseases confront sustainable development of the fishery sector and overuse of antibiotics is considered a major challenge. Antibiotics are used in aquaculture for both therapeutic and prophylactic reasons. Various antimicrobials used in human medicine are also used for food animals even for non-therapeutic use. The use of antibiotics in health management of aquaculture farming is of great concern due to possible residues in aquatic products and in the development of antibiotic resistance. In 2005 the Vietnamese government first promulgated a list of medicines, chemicals and antibiotics that are banned or limited for use in aquaculture and this is regularly updated and amended to tackle the growing problem of antibiotic resistance.
Publisher: Elsevier BV
Date: 2011
Publisher: Elsevier BV
Date: 03-2012
DOI: 10.1016/J.IJFOODMICRO.2011.12.032
Abstract: Antimicrobial resistance is a global problem. It is most prevalent in developing countries where infectious diseases remain common, the use of antibiotics in humans and animals is widespread, and the replacement of older antibiotics with new generation antibiotics is not easy due to the high cost. Information on antibiotic resistance phenotypes and genotypes of Salmonella spp. in food animals and humans in different countries and geographic regions is necessary to combat the spread of resistance. This will improve the understanding of antibiotic resistance epidemiology, tracing of new emerging pathogens, assisting in disease treatment, and enhancing prudent use of antibiotics. However, the extent of antibiotic resistance in food-borne pathogens and humans in many developing countries remains unknown. The goal of this review is to discuss the current state of antibiotic resistance of non-typhoid Salmonella spp. in food-producing animals, retail meat and humans from South East Asia. It is focused on resistance characteristics of traditional and "critically important" antibiotics in this region, and the emergence of multidrug resistant strains and genetic elements that contribute to the development of multidrug resistance, including integrons and the Salmonella Genomic Island (SGI).
Publisher: Elsevier BV
Date: 11-2021
Publisher: American Society for Microbiology
Date: 12-10-2017
Abstract: Lactobacillus plantarum strain A6, a strong acid producer, was isolated from a Vietnamese fermented sausage (nem chua). Here, we report the genome sequence of this strain (3,368,579 bp).
Publisher: Mary Ann Liebert Inc
Date: 08-2018
Abstract: C ylobacter jejuni and C ylobacter coli play a major role in bacteria-related foodborne illness in humans. Recently, a newly identified species, C ylobacter hepaticus, was shown to be the causative agent of spotty liver disease in chickens. The pathogenic potential of C. hepaticus in humans is unknown. This new species contains genes usually used to detect C. jejuni and C. coli in DNA-based detection methods, such as the hippuricase (hipO) gene and the glyA (serine hydroxymethyltransferase) gene, with a high degree of similarity. Therefore, polymerase chain reaction (PCR) primers used to detect these species need to be evaluated carefully to prevent misidentification of these important C ylobacter species. A multiplex PCR was developed and optimized to simultaneously and specifically identify the presence of C. jejuni, C. coli, and C. hepaticus in chicken s les containing high-complexity microbiota. The assay represents a new diagnostic tool for investigating the epidemiology of C ylobacter colonization in poultry and environmental s les. It may also be applicable to the investigation of C ylobacter contamination in food and in outbreaks of c ylobacteriosis.
Publisher: Elsevier BV
Date: 08-2020
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.VETMIC.2016.12.033
Abstract: Spotty liver disease (SLD) in chickens can present with variable impacts on mortality and production, ranging from sporadic mortalities of in idual birds and no notable impact on production to severe reduction in egg output and increased mortality in layer flocks of greater than 1% per day. It was first described over 60 years ago and there have been sporadic reports of the disease throughout the intervening decades, particularly in the US, UK and Germany. Recently it has become of increasing concern as outbreaks of the disease have occurred more frequently, particularly in the Australian poultry industry. An understanding of the causes of the disease has proven elusive. However, recent studies of SLD have strongly implicated a novel C ylobacter species, C ylobacter hepaticus, as the causative agent. Here we demonstrate that C. hepaticus is highly invasive in LMH cells, an immortalised chicken hepatoma cell line, and can induce disease when orally delivered to mature layer birds. Challenged birds developed liver lesions, typical of those seen in field clinical cases, within 5days of challenge. The bacterium used to challenge the birds could be recovered from the diseased liver and from bile, thus demonstrating that C. hepaticus is the causative agent of chicken SLD.
Publisher: Elsevier BV
Date: 08-2017
DOI: 10.1016/J.VETMIC.2017.06.022
Abstract: Spotty liver disease (SLD) causes significant egg production losses and mortality in chickens and is therefore a disease of concern for some sectors of the poultry industry. Although the first reports of the disease came from the United States in the 1950s it is only recently that the organism that causes the disease was identified, isolated, and characterised as a new bacterial species, C ylobacter hepaticus. The first isolations of C. hepaticus were from the livers and bile of SLD affected birds. Isolates could only be recovered from s les that had a monoculture of C. hepaticus in the tissues, as a selective culturing method has not yet been developed. In non-selective growth conditions the slow growing C. hepaticus is quickly outgrown by many other members of the chicken microbiota. Therefore, it is currently not possible to use a culturing approach to evaluate C. hepaticus carriage in tissues, such as the gastrointestinal tract (GIT), that also carry complex microbial populations. As it is suspected that birds become infected via the faecal-oral route it is important that pathogen carriage in the GIT is investigated. In the present study, a specific and sensitive quantitative real-time PCR assay, based on the glycerol kinase gene of C. hepaticus, was developed. The assay facilitated the detection and quantification of C. hepaticus in tissue s les from clinical cases of SLD. It was shown that in infected birds C. hepaticus colonises the small intestine, increasing in abundance from duodenum to ileum, and is at highest levels within the ceaca. C. hepaticus was also readily detected in cloacal swabs, indicating that thecl-oral infection.
Publisher: American Society for Microbiology
Date: 15-12-2007
DOI: 10.1128/AEM.00973-07
Abstract: This study was conducted to examine the rate of contamination and the molecular characteristics of enteric bacteria isolated from a selection of food sources in Vietnam. One hundred eighty raw food s les were tested 60.8% of meat s les and 18.0% of shellfish s les were contaminated with Salmonella spp., and more than 90% of all food sources contained Escherichia coli . The isolates were screened for antibiotic resistance against 15 antibiotics, and 50.5% of Salmonella isolates and 83.8% of E. coli isolates were resistant to at least one antibiotic. Isolates were examined for the presence of mobile genetic elements conferring antibiotic resistance. Fifty-seven percent of E. coli and 13% of Salmonella isolates were found to contain integrons, and some isolates contained two integrons. Sequencing results revealed that the integrons harbored various gene cassettes, including aadA1 , aadA2 , and aadA5 (resistance to streptomycin and spectinomycin), aacA4 (resistance to aminoglycosides), the dihydrofolate reductase gene cassettes dhfrXII , dfrA1 , and dhfrA17 (trimethoprim resistance), the beta-lactamase gene bla PSE1 ( icillin resistance), and catB3 (chlor henicol resistance). Plasmids were also detected in all 23 antibiotic-resistant Salmonella isolates and in 33 E. coli isolates. Thirty-five percent of the Salmonella isolates and 76% of the E. coli isolates contained plasmids of more than 95 kb, and some of the isolates contained two large plasmids. Conjugation experiments showed the successful transfer of all or part of the antibiotic resistance phenotypes among the Salmonella and E. coli food isolates. Our results show that enteric bacteria in raw food s les from Vietnam contain a pool of mobile genetic elements and that the transfer of antibiotic resistance can readily occur between similar bacteria.
Publisher: American Society for Microbiology
Date: 11-05-2021
DOI: 10.1128/AEM.00392-21
Abstract: Therapeutic proteins such as antigens can be used to prevent infectious diseases in poultry. However, traditional vaccine delivery by intramuscular or subcutaneous injection generally has not proven effective for mucosa-dwelling microorganisms that live within the gastrointestinal tract.
Publisher: Public Library of Science (PLoS)
Date: 10-12-2019
Publisher: Springer Science and Business Media LLC
Date: 12-11-2020
Start Date: 06-2021
End Date: 06-2025
Amount: $989,000.00
Funder: Australian Research Council
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