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1.
Int J Food Microbiol ; 340: 109042, 2021 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-33461002

RESUMEN

The development of antimicrobial resistance in foodborne pathogens is a growing public health concern. This study was undertaken to determine the antimicrobial susceptibility of Salmonella enterica subspecies enterica isolated from the Australian commercial egg layer industry. S. enterica subspecies enterica (n=307) isolated from Australian commercial layer flock environments (2015-2018) were obtained from reference, research and State Government laboratories from six Australian states. All Salmonella isolates were serotyped. Antimicrobial susceptibility testing (AST) for 16 antimicrobial agents was performed by broth microdilution. Antimicrobial resistance genes and sequence types (STs) were identified in significant isolates by whole genome sequencing (WGS). Three main serotypes were detected, S. Typhimurium (n=61, 19.9%), S. Senftenburg (n=45, 14.7%) and S. Agona (n=37, 12.1%). AST showed 293/307 (95.4%) isolates were susceptible to all tested antimicrobial agents and all isolates were susceptible to amoxicillin-clavulanate, azithromycin, ceftiofur, ceftriaxone, ciprofloxacin, colistin, florfenicol, gentamicin, kanamycin and trimethoprim-sulfamethoxazole. Low levels of non-susceptibility were observed to streptomycin (2.3%, n=7), sulfisoxazole (2.0%, n=6), chloramphenicol (1.3%, n=4) and tetracycline (1.0%, n=3). Very low levels of non-susceptibility were observed to ampicillin (2/307; 0.7%) and cefoxitin (2/307; 0.7%). Two isolates (S. Havana and S. Montevideo), exhibited multidrug-resistant phenotypes to streptomycin, sulfisoxazole and tetracycline and possessed corresponding antimicrobial resistance genes (aadA4, aac(6')-Iaa, sul1, tetB). One S. Typhimurium isolate was resistant to ampicillin and tetracycline, and possessed both tetA and blaTEM-1B. WGS also identified these isolates as belonging to ST4 (S. Montevideo), ST578 (S. Havana) and ST19 (S. Typhimurium). The absence of resistance to highest priority critically important antimicrobials as well as the extremely low level of AMR generally among Australian commercial egg layer Salmonella isolates likely reflect Australia's conservative antimicrobial registration policy in food-producing animals and low rates of antimicrobial use within the industry.

2.
Vaccines (Basel) ; 8(4)2020 Nov 19.
Artículo en Inglés | MEDLINE | ID: mdl-33228065

RESUMEN

Salmonella Typhimurium is among the most common causes of bacterial foodborne gastrointestinal disease in humans. Food items containing raw or undercooked eggs are frequently identified during traceback investigation as the source of the bacteria. Layer hens can become persistently infected with Salmonella Typhimurium and intermittently shed the bacteria over the course of their productive lifetime. Eggs laid in a contaminated environment are at risk of potential exposure to bacteria. Thus, mitigating the bacterial load on farms aids in the protection of the food supply chain. Layer hen producers use a multifaceted approach for reducing Salmonella on farms, including the all-in-all-out management strategy, strict biosecurity, sanitization, and vaccination. The use of live attenuated Salmonella vaccines is favored because they elicit a broader host immune response than killed or inactivated vaccines that have been demonstrated to provide cross-protection against multiple serovars. Depending on the vaccine, two to three doses of Salmonella Typhimurium vaccines are generally administered to layer hens within the first few weeks. The productive life of a layer hen, however, can exceed 70 weeks and it is unclear whether current vaccination regimens are effective for that extended period. The objective of this review is to highlight layer hen specific challenges that may affect vaccine efficacy.

3.
Front Microbiol ; 11: 581201, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33072053

RESUMEN

Determining the viable and non-viable load of foodborne pathogens in animal production can be useful in reducing the number of human outbreaks. In this study, we optimized a PMAxxTM-based qPCR for quantifying viable and non-viable load of Salmonella from soil collected from free range poultry environment. The optimized nucleic acid extraction method resulted in a significantly higher (P < 0.05) yield and quality of DNA from the pure culture and Salmonella inoculated soil samples. The optimized primer for the amplification of the invA gene fragment showed high target specificity and a minimum detection limit of 102 viable Salmonella from soil samples. To test the optimized PMAxxTM-based qPCR assay, soil obtained from a free range farm was inoculated with Salmonella Enteritidis or Salmonella Typhimurium, incubated at 5, 25, and 37°C over 6 weeks. The survivability of Salmonella Typhimurium was significantly higher than Salmonella Enteritidis. Both the serovars showed moisture level dependent survivability, which was significantly higher at 5°C compared with 25°C and 37°C. The PMAxxTM-based qPCR was more sensitive in quantifying the viable load compared to the culture method used in the study. Data obtained in the current study demonstrated that the optimized PMAxxTM-based qPCR is a suitable assay for quantification of a viable and non-viable load of Salmonella from poultry environment. The developed assay has applicability in poultry diagnostics for determining the load of important Salmonella serovars containing invA.

4.
Food Microbiol ; 92: 103555, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32950149

RESUMEN

Raw egg-based sauces, such as mayonnaise and aioli, are frequently identified as sources of Salmonella during outbreaks of human cases of foodborne gastrointestinal disease. In this study, we surveyed aioli and mayonnaise recipes from different popular food websites to identify potential risk factors that may lead to the survival of Salmonella Typhimurium. In laboratory experiments, different ratios of food acids were used to determine if lemon juice, vinegar, or a combination of both restricted Salmonella Typhimurium culturability. We found that as long as the pH was below 4.2, bacterial culturability was limited. The use of whole egg alone or in combination with egg yolk was also investigated. Sauce preparations containing whole egg exhibited higher pH and supported Salmonella Typhimurium culturability longer than those containing yolk only. Ten restaurant prepared sauces were also obtained to further characterize the effect of preparation variability. Sauce preparations with a pH ≤ 3.8 did not support bacterial culturability after 4 h incubation at any temperature. The higher the pH the longer Salmonella Typhimurium remained culturable. Based on this study, it is recommended that raw egg-based foods are acidified, then stored at room temperature for at least 4 h prior to consumption.

5.
Appl Microbiol Biotechnol ; 104(21): 9327-9342, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32960293

RESUMEN

Temporal regulation of global gene expression in the caeca of chickens infected with Salmonella Typhimurium has not been investigated previously. In this study, we performed the transcriptome analysis of the caeca of Salmonella Typhimurium challenged chicks to understand the regulation of the mucosal immune system in a temporal manner. The Salmonella infection resulted in the activation of the caecal immune system by the upregulation of the differentially expressed genes (DEGs; false discovery rate (FDR) < 0.05; log2 fold change > 1) involved in biological pathways such as Toll-like receptor signaling pathway, Salmonella infection, cytokine-cytokine receptor interaction, phagosome, apoptosis and intestinal immune network for IgA production. The activation of biological pathways such as RIG-I-like receptor signaling pathway, ErbB signaling pathway and cellular senescence showed a time-dependent response of the host immune system. A 49% increase in the DEGs on day 7 compared with day 3 post-infection (p.i.) suggested a time-dependent role of multiple genes such as AvBD1, AvBD2, AvBD7, IL2, IL10, IL21, SIVA1, CD5, CD14 and GPR142 in the regulation of the immune system. Nested network analysis of the individual biological pathways showed that IL6 played a significant role in the immune system regulation by activating the pathways, including Toll-like receptor signaling pathway, Salmonella infection, intestinal immune network for IgA production and C-type lectin receptor signaling pathway. The downregulated DEGs (FDR < 0.05; log2 fold change < -1) showed that Salmonella challenge affected the functions of pathways, such as tryptophan metabolism, retinol metabolism, folate biosynthesis and pentose and glucoronate interconversions, suggesting the disruption of cellular mechanisms involved in nutrient synthesis, absorption and metabolism. Overall, the immune response was temporally regulated through the activation of Toll-like signaling receptor pathway, cytokine-cytokine interactions and Salmonella infection, where IL6 played a significant role in the modulation of caecal immune system against Salmonella Typhimurium. KEY POINTS: • The immune response to Salmonella Typhimurium challenge was temporally regulated in the caeca of chickens. • Many newly identified genes have been shown to be involved in the activation of the immune system. • Toll-like receptors and interleukins played a key role in immune system regulation.

6.
Appl Environ Microbiol ; 86(13)2020 06 17.
Artículo en Inglés | MEDLINE | ID: mdl-32332137

RESUMEN

The microbiota plays a vital role in maintaining gut health and influences the overall performance of chickens. Most gut microbiota-related studies have been performed in broilers, which have different microbial communities compared to those of layers. The normal gut microbiota of laying chickens is dominated by Proteobacteria, Firmicutes, Bacteroidetes, Fusobacteria, and Actinobacteria at the phylum level. The composition of the gut microbiota changes with chicken age, genotype, and production system. The metabolites of gut microbiota, such as short-chain fatty acids, indole, tryptamine, vitamins, and bacteriocins, are involved in host-microbiota cross talk, maintenance of barrier function, and immune homeostasis. Resident gut microbiota members also limit and control the colonization of foodborne pathogens. In-feed supplementations of prebiotics and probiotics strengthen the gut microbiota for improved host performance and colonization resistance to gut pathogens, such as Salmonella and Campylobacter The mechanisms of action of prebiotics and probiotics come through the production of organic acids, activation of the host immune system, and production of antimicrobial agents. Probiotic candidates, including Lactobacillus, Bifidobacterium, Bacillus, Saccharomyces, and Faecalibacterium isolates, have shown promising results toward enhancing food safety and gut health. Additionally, a range of complex carbohydrates, including mannose oligosaccharides, fructo-oligosaccharides, and galacto-oligosaccharides, and inulin are promising candidates for improving gut health. Here, we review the potential roles of prebiotics and probiotics in the reshaping of the gut microbiota of layer chickens to enhance gut health and food safety.


Asunto(s)
Pollos/microbiología , Inocuidad de los Alimentos , Microbioma Gastrointestinal/efectos de los fármacos , Prebióticos/administración & dosificación , Probióticos/administración & dosificación , Animales , Femenino
7.
Front Microbiol ; 11: 503, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32269561

RESUMEN

Broiler chickens frequently become colonized by Campylobacter species. As a consequence, Campylobacter, can enter the poultry meat supply chain and represents a significant risk for human public health. A number of on-farm biosecurity and processing measures are used to mitigate the load of Campylobacter on chicken meat. In many countries, chlorine is commonly used as a biocide in processing plants to reduce bacterial loads on poultry carcasses but there is limited evidence of its effectiveness on Campylobacter. In this study, 116 Campylobacter isolates (89 C. jejuni and 27 C. coli) were isolated from poultry meat carcasses prior to the inside/outside wash step and used in in vitro assays exploring the efficacy of chlorine. A high proportion of isolates exhibited MIC and MBC values of 128 ppm but organic material present in the broth likely affected this result. Thus, additional bactericidal assays (time kill and chlorine inactivation) were used to characterize the response of C. jejuni isolates to different concentrations of chlorine. At 106 CFU, C. jejuni was found to be highly sensitive to concentrations of chlorine and was inhibited at low concentrations (0.2-2.0 ppm). At a higher bacterial load (108 CFU), variation in the response of different C. jejuni isolates was observed. One isolate was growth inhibited at 1.8 ppm while another required 16 ppm. At 108 CFU, C. jejuni could be resuscitated following exposure to chlorine highlighting a potential limitation of chlorine use. Analysis of UV leakage indicated that high chlorine concentrations resulted in increased 280 nm absorbance values suggesting bacterial membrane damage. Scanning electron and transmission electron microscopy were performed to characterize the morphological effects of chlorine exposure. Some effects of chlorine exposure included changes in shape (coccoid, or elongated), cellular degeneration, and shriveled bacterial cells. Interestingly, C. jejuni cells with normal morphology were also observed in the chlorine exposed group and represent a population of cells that could be resuscitated. This study is useful for the chicken meat industry and provides data for future optimization of chlorine use in reducing Campylobacter loads.

8.
J Anim Sci Biotechnol ; 11: 29, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32211190

RESUMEN

Background: The gut microbiota plays an important role in the colonisation resistance and invasion of pathogens. Salmonella Typhimurium has the potential to establish a niche by displacing the microbiota in the chicken gut causing continuous faecal shedding that can result in contaminated eggs or egg products. In the current study, we investigated the dynamics of gut microbiota in laying chickens during Salmonella Typhimurium infection. The optimisation of the use of an infeed probiotic supplement for restoration of gut microbial balance and reduction of Salmonella Typhimurium load was also investigated. Results: Salmonella infection caused dysbiosis by decreasing (FDR < 0.05) the abundance of microbial genera, such as Blautia, Enorma, Faecalibacterium, Shuttleworthia, Sellimonas, Intestinimonas and Subdoligranulum and increasing the abundance of genera such as Butyricicoccus, Erysipelatoclostridium, Oscillibacter and Flavonifractor. The higher Salmonella Typhimurium load resulted in lower (P < 0.05) abundance of genera such as Lactobacillus, Alistipes, Bifidobacterium, Butyricimonas, Faecalibacterium and Romboutsia suggesting Salmonella driven gut microbiota dysbiosis. Higher Salmonella load led to increased abundance of genera such as Caproiciproducens, Acetanaerobacterium, Akkermansia, Erysipelatoclostridium, Eisenbergiella, EscherichiaShigella and Flavonifractor suggesting a positive interaction of these genera with Salmonella in the displaced gut microbiota. Probiotic supplementation improved the gut microbiota by balancing the abundance of most of the genera displaced by the Salmonella challenge with clearer effects observed with continuous supplementation of the probiotic. The levels of acetate and butyrate in the faeces were not affected (P > 0.05) by Salmonella challenge and the butyrate level was increased by the continuous feeding of the probiotic. Probiotic supplementation in Salmonella challenged chickens resulted in higher level of propionate. Continuous probiotic supplementation decreased (P < 0.05) the overall mean load of Salmonella in faeces and had a significant effect on Salmonella load reduction in internal organs. Conclusions: Salmonella challenge negatively impacts the diversity and abundance of many gut microbial genera involved in important functions such as organic acid and vitamin production. Strategic feeding of a Bacillus based probiotic helps in restoring many of the microbial genera displaced by Salmonella Typhimurium challenge.

9.
Food Microbiol ; 87: 103384, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-31948625

RESUMEN

Single-aged caged layer hen flocks were monitored for Salmonella over the course of their lifetime. Chicks from both flocks were Salmonella negative at hatch and remained negative during rearing. Pullets were transported to production farms at 15 weeks of age. Pre-population dust swabs collected from both production sheds had a high percentage of Salmonella positive samples (80 and 90%). Flocks were sampled at regular intervals until 70-72 weeks of age. The proportion of Salmonella positive samples and mean load detected on eggs was low on both farms. Analysis of dust samples revealed that Salmonella persisted in dust over 8 weeks. Dust total moisture content and water activity appears to influence bacterial persistence. On egg grading equipment, only suction cups prior to egg washing were Salmonella positive (mean proportion Salmonella positive samples 0.13 ± 0.07; mean load of 18.6 ± 12.31 MPN/ml). An egg washing experiment demonstrated that while washing reduced the total Salmonella load from eggshell surfaces, no effect was observed for shell pores. These results demonstrate that despite environmental contamination on farm, Salmonella contamination of eggs is low and is further minimized by washing.


Asunto(s)
Pollos/fisiología , Huevos/microbiología , Contaminación de Alimentos/análisis , Animales , Australia , Pollos/microbiología , Huevos/análisis , Granjas , Femenino , Contaminación de Alimentos/estadística & datos numéricos , Manipulación de Alimentos
10.
Appl Microbiol Biotechnol ; 104(1): 319-334, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31758235

RESUMEN

Positive modulation of gut microbiota in laying chickens may offer a strategy for reduction of Salmonella Typhimurium shedding and production of safer poultry products. In the current study, the caecal luminal microbiota of laying chicks was studied using 16S rRNA amplicon sequencing on DNA obtained from the chicks that were offered supplementation with commercial probiotics, synbiotics and/or Salmonella Typhimurium challenge. The load of Salmonella Typhimurium in various organs was quantified. Irrespective of the probiotics and synbiotics supplementation and Salmonella Typhimurium challenge, caecal microbiota was dominated by 22 distinct bacterial genera and 14 families that clustered into Actinobacteria, Proteobacteria and Firmicutes at phylum level. Taken together, probiotics and synbiotics supplementation increased (false discovery rate; FDR < 0.05) the abundance of Ruminococcus, Trabulsiella, Bifidobacterium, Holdemania and Oscillospira, indicating their role in maintaining gut health through lowering luminal pH and digestion of complex polysaccharides. Salmonella Typhimurium challenge decreased the abundance of Trabulsiella, Oscillospira, Holdemania, Coprococcus, Bifidobacterium and Lactobacillus and increased Klebsiella and Escherichia, indicating its role in caecal dysbiosis. Although probiotics and synbiotics supplementation positively modulated the caecal microbiota, they were not effective in significantly (P > 0.05) reducing Salmonella Typhimurium load in caecal tissue and invasion into vital organs such as liver and spleen. The early colonisation of laying chick caeca by probiotics and synbiotics had the potential to positively influence luminal microbiota; however, the microbial abundance and diversity were not sufficient to significantly reduce the shedding of Salmonella Typhimurium in faeces or invasion into internal organs during this study.


Asunto(s)
Derrame de Bacterias , Ciego/microbiología , Microbiota , Probióticos/administración & dosificación , Salmonelosis Animal/microbiología , Simbióticos/administración & dosificación , Alimentación Animal/microbiología , Animales , Carga Bacteriana , Pollos/microbiología , Heces/microbiología , Femenino , Hígado/microbiología , Enfermedades de las Aves de Corral/microbiología , ARN Ribosómico 16S , Salmonella typhimurium/genética , Salmonella typhimurium/patogenicidad , Bazo/microbiología
11.
Artículo en Inglés | MEDLINE | ID: mdl-31795463

RESUMEN

Chicken meat can potentially become contaminated with bacteria at the processing plant. In Australia, there is currently a lack of knowledge on the parameters and indications of use of non-chlorine based treatments in the chicken meat processing plants. Chlorine is widely used as a sanitizer in Australian chicken meat processing plants but due to occupational health and safety concerns and consumer perception, there is a need to identify alternative sanitizers. This study aimed to assess the efficacy of four different sanitizers in reducing the microbial load from naturally contaminated chicken meat carcasses collected from the processing plants in South Australia. There was a significant variation in a load of Campylobacter and total viable count (TVC) between samples collected from two different processing plants and within carcass batches collected from the same plant that was tested during the study. All sanitizers generally reduced the load of Campylobacter on chicken meat carcasses. Treatment with acidified sodium chlorite significantly reduced the level of Salmonella enterica serovars at all temperatures tested during this study. These findings are helpful to the industry for selection of the appropriate sanitizers. Findings are also useful for the regulatory authorities in Australia for providing approval for the use of sanitizers.


Asunto(s)
Pollos/microbiología , Desinfectantes/farmacología , Microbiología de Alimentos , Animales , Australia , Campylobacter/aislamiento & purificación , Cloro/administración & dosificación , Recuento de Colonia Microbiana , Australia del Sur
12.
Vet Res ; 50(1): 71, 2019 Sep 24.
Artículo en Inglés | MEDLINE | ID: mdl-31551081

RESUMEN

Eggs and raw or undercooked egg-containing food items are frequently identified as the bacterial source during epidemiolocal investigation of Salmonella outbreaks. Multi-locus variable number of tandem repeats analysis (MLVA) is a widely used Salmonella typing method enabling the study of diversity within populations of the same serotype. In vivo passage, however, has been linked with changes in MLVA type and more broadly the Salmonella genome. We sought to investigate whether in vivo passage through layer hens had an effect on MLVA type as well as the bacterial genome and whether any mutations affected bacterial virulence. Layer hens were infected with either Salmonella Typhimurium DT9 (03-24-11-11-523) as part of a single infection or were co-infected with an equal amount of Salmonella Mbandaka. Salmonella shedding in both single and co-infected birds was variable over the course of the 16-week experiment. Salmonella Typhimurium and Salmonella Mbandaka were identified in feces of co-infected birds. Salmonella colonies isolated from fecal samples were subtyped using MLVA. A single change in SSTR-6 was observed in Salmonella Typhimurium strains isolated from co-infected birds. Isolates of Salmonella Typhimurium of both the parent (03-24-11-11-523) and modified (03-24-12-11-523) MLVA type were sequenced and compared with the genome of the parent strain. Sequence analysis revealed that in vivo passaging resulted in minor mutation events. Passaged isolates exhibited significantly higher invasiveness in cultured human intestinal epithelial cells than the parent strain. The microevolution observed in this study suggests that changes in MLVA may arise more commonly and may have clinical significance.


Asunto(s)
Pollos , Genoma Bacteriano/genética , Mutación/fisiología , Enfermedades de las Aves de Corral/fisiopatología , Salmonelosis Animal/fisiopatología , Salmonella typhimurium/fisiología , Animales , Células CACO-2 , Coinfección/microbiología , Coinfección/fisiopatología , Coinfección/veterinaria , Heces/microbiología , Femenino , Humanos , Repeticiones de Minisatélite , Tipificación de Secuencias Multilocus/veterinaria , Enfermedades de las Aves de Corral/microbiología , Salmonelosis Animal/microbiología , Salmonella enterica/fisiología , Salmonella typhimurium/genética , Pase Seriado , Virulencia
13.
Vet Res ; 50(1): 58, 2019 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-31362780

RESUMEN

Human cases of salmonellosis are frequently liked with the consumption of contaminated table eggs. Recently, there has been an increase in consumer demand for cage-free eggs precipitating the need for a greater understanding of Salmonella dynamics in free-range production systems. A longitudinal study was conducted to determine the points in production where birds are most likely to be exposed to Salmonella and where the risk of egg contamination is highest. In this study, two free-range flocks were sampled from hatch to the end of production. At hatch, all chicks were Salmonella negative and remained negative during rearing. During production, the proportion of positive samples was low on both farms. Salmonella positive samples were detected intermittently for Flock A. Dust, nest box, and egg belt swabs had the highest proportion of positive samples and highest overall loads of Salmonella. The egg grading floor was swabbed at different points following the processing of eggs from Flock A. Only the suction cups that handle eggs prior to egg washing tested positive for Salmonella. Swabs collected from machinery handling eggs after washing were Salmonella negative. During production, positive samples from Flock B were observed at only single time point. Dust has been implicated as a source of Salmonella that can lead to flock to flock contamination. Bulk dust samples were collected and tested for Salmonella. The proportion of positive dust samples was low and is likely due to physical parameters which are not likely to support the survival of Salmonella in the environment.


Asunto(s)
Crianza de Animales Domésticos , Derrame de Bacterias , Pollos , Enfermedades de las Aves de Corral/epidemiología , Salmonelosis Animal/epidemiología , Salmonella/fisiología , Crianza de Animales Domésticos/métodos , Animales , Australia/epidemiología , Estudios Longitudinales , Óvulo/microbiología , Enfermedades de las Aves de Corral/microbiología , Prevalencia , Factores de Riesgo , Salmonelosis Animal/microbiología
14.
Animals (Basel) ; 9(4)2019 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-31018562

RESUMEN

In the last decade, research has targeted the evaluation of local feed ingredients for use in monogastric diets to alleviate the high cost of production of livestock at smallholder levels in Papua New Guinea (PNG). The PNG smallholder poultry production system involves many families who rear multiple batches of meat birds every year. This study was conducted to evaluate the levels of enteric pathogens in the caeca of broilers fed with sweetpotato diets with varying levels of non-starch polysaccharides (NSP). Selection of a sweetpotato variety for use in broiler diets should be based on the total NSP content. In particular, varieties with low soluble NSPs are economical to use as Apparent Metabolizable Energy (AME) values are within the desired range for poultry and there is minimal need to include enzymes to improve NSP digestibility. The use of varieties with a low total NSP is also advantageous as the numbers of Clostridium perfringens was lower in broilers fed with these sweetpotato varieties. The level of Campylobacter and Salmonella levels were high in the ceca of birds fed with the sweetpotato varieties with high total NSP. These levels can be reduced with the inclusion of enzymes. This information will assist in the efficient use of local varieties of sweetpotato in PNG by small holder poultry farmers for sustainable poultry production and the commercial industry.

15.
Front Microbiol ; 9: 1380, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29997596

RESUMEN

Salmonella remains one of the most common causes of bacterial foodborne gastrointestinal disease in humans. Raw eggs or food items containing undercooked eggs are frequently identified as the source of Salmonella. Salmonella Typhimurium contamination of table eggs most commonly occurs when they are laid in a contaminated environment. Several control strategies, including vaccination, are widely used to mitigate the total Salmonella load. It is unclear, however, whether live attenuated Salmonella vaccines are efficacious over the life span of a layer hen. Live attenuated Salmonella vaccines have been favored due to their ability to illicit a strong humoral immune response. The lifespan of a layer hen ranges between 60 and 80 weeks and the long term efficacy of attenuated vaccine strains has not been investigated. In this study, commercial brown layer chicks were vaccinated at day old, 6 weeks of age, and again at 10 weeks of age with the Bioproperties VaxsafeTM STM1 aroA mutant vaccine. Birds were challenged at 18 weeks of age with Salmonella Typhimurium DT9 (MLVA 03 15 08 11 550). Feces and eggs were monitored for S. Typhimurium for 40 weeks post-infection. Birds produced a strong immune response following the final dose which was administered intramuscularly. The serum antibody response to S. Typhimurium DT9 infection did not differ between challenged groups. Fecal shedding and egg contamination was highly variable and did not differ significantly between vaccinated and unvaccinated birds that had been challenged with S. Typhimurium DT9. Total bacterial load in feces was quantified using qPCR. No significant difference was detected between unvaccinated and vaccinated birds after challenge.

16.
BMC Microbiol ; 18(1): 78, 2018 07 20.
Artículo en Inglés | MEDLINE | ID: mdl-30029593

RESUMEN

BACKGROUND: Salmonella vaccination is one of the control measure that farmers can use to reduce bacterial shedding in their flocks. This study aimed to examine the efficacy of the Vaxsafe® ST (Strain STM-1) attenuated live vaccine administered as ocular and oral doses followed by an intramuscular (IM) dose in rearing, in reducing contamination by Salmonellae of both eggs and the environment in the commercial multi-age cage layer sheds. A randomised controlled trial was conducted up to 26 weeks post last vaccine on two different multi-age caged egg farms. RESULTS: No clinical symptoms were observed following IM administration of STM-1 during rearing. Following the first two STM-1 doses, both vaccinated and unvaccinated birds exhibited antibody titres below the positive cut-off value, however after IM administration of STM-1, antibody titres in the vaccinated group were above the cut-off value. Wild type Salmonella Typhimurium was not detected during the rearing of pullets. During production, the antibody titres were significantly higher in the vaccinated group at all sampling points during this trial. There was no significant difference in the prevalence of Salmonella (detected by culture and PCR method) between the vaccinated and unvaccinated groups on the egg belt and faeces in early lay. Wild-type Salmonella spp. were consistently found in dust samples. Quantitative PCR (qPCR) assay was able to differentiate between the live vaccine strain and wild type Salmonella. The load of wild-type Salmonella in shed environment was relatively low (1.3 log10 ± 0.48 CFU/m2 of surface area). CONCLUSION: Given that Salmonella Typhimurium and other serovars are able to survive/persist in the shed environment (such as in dust), regular cleaning and or removal of dust from shed is important. Use of the Vaxsafe® ST vaccine in multi-age flocks is "not an ultimate intervention" for reduction of Salmonella Typhimurium because of the complexities involved in achieving control, such as the efficacy of cleaning of sheds, the lack of resting periods between batches and the possible carry over of contamination from existing flocks. Hence implementation of more than one or several interventions strategies is essential.


Asunto(s)
Huevos/microbiología , Microbiología Ambiental , Salmonelosis Animal/microbiología , Vacunas contra la Salmonella/inmunología , Salmonella typhimurium/inmunología , Crianza de Animales Domésticos , Animales , Anticuerpos Antibacterianos/sangre , Carga Bacteriana , Pollos , Heces/microbiología , Femenino , Distribución Aleatoria , Salmonelosis Animal/inmunología , Salmonelosis Animal/prevención & control , Vacunas contra la Salmonella/normas , Vacunas Atenuadas/inmunología , Vacunas Atenuadas/normas
17.
Zoonoses Public Health ; 65(6): 736-741, 2018 09.
Artículo en Inglés | MEDLINE | ID: mdl-29761650

RESUMEN

Vaccination of chicks with Salmonella (S.) Typhimurium aroA deletion mutants has previously been shown to inhibit intestinal colonization of wild-type S. Typhimurium strains. In Australia, Bioproperties VaxSafe™ STM1 strain is the only licensed and commercially available S. Typhimurium vaccine. This vaccine is a live attenuated aroA deletion mutant. Currently, it is recommended that the first dose of the STM1 vaccine is administered through coarse spray. It is unclear whether this mode of administration effectively permits intestinal colonization. Furthermore, it is not known whether the STM1 strain prevents or inhibits Salmonella colonization of chicks following this first dose. This study investigated both in vitro and in vivo colonization parameters. Invasiveness was assessed using an in vitro invasion assay into sections of ileum and caecum collected from day-old chicks. The S. Typhimurium definitive types (DT) 9 and 44 exhibited the greatest invasion into both intestinal segments. STM1 was invasive but was significantly less so than both isolates of S. Typhimurium. In dual and triple infections, no competitive microbial interactions between STM1 and wild-type Salmonella were observed. In vivo colonization inhibition was also tested. Vaccinated and nonvaccinated day-old chicks were challenged with S. Typhimurium DT9. Both STM1 and S. Typhimurium DT9 were found in spleen, liver, ileum, caecum and caecal contents from day 2 postinfection. No significant exclusion effect was observed in vaccinated and challenged chicks.


Asunto(s)
Pollos/microbiología , Intestinos/microbiología , Enfermedades de las Aves de Corral/prevención & control , Vacunas contra la Salmonella/inmunología , Salmonella typhimurium , Animales , Portador Sano , Embrión de Pollo , Femenino , Masculino , Enfermedades de las Aves de Corral/microbiología , Salmonella typhimurium/genética , Salmonella typhimurium/inmunología
18.
Crit Rev Microbiol ; 44(3): 290-303, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-28903617

RESUMEN

Globally, Salmonella enterica subsp. enterica is one of the most commonly reported causes of foodborne illness in humans. Contaminated food products of animal origin, particularly egg and egg products are frequently implicated in outbreaks of human salmonellosis. Salmonella enteritidis is frequently involved in egg and egg products-associated foodborne outbreaks in the USA and UK. However, in Australia and New Zealand, human infections caused by this serovar occur as a result of infection acquired while overseas travel, with Salmonella typhimurium being a predominant cause of local foodborne outbreaks. In this paper, an overview of Salmonella epidemiology on laying farms, egg-related Salmonella outbreaks in humans, and regulatory practises to control Salmonella across USA, UK, Australia and New Zealand is provided. Considering the estimated production of eggs in the USA, UK, Australia and New Zealand in 2015, the risk of foodborne illness in general is quite low for humans consuming eggs. Salmonella diagnostics, reporting and surveillance systems have improved over the years and will continue to improve in the years to come. However, given the number of different emerging Salmonella serovars a regular review of Salmonella control strategies from farm to fork is required.


Asunto(s)
Huevos/microbiología , Enfermedades Transmitidas por los Alimentos/microbiología , Infecciones por Salmonella/microbiología , Animales , Australia , Pollos , Contaminación de Alimentos/análisis , Contaminación de Alimentos/prevención & control , Enfermedades Transmitidas por los Alimentos/prevención & control , Humanos , Nueva Zelanda , Infecciones por Salmonella/prevención & control , Reino Unido , Estados Unidos
19.
Avian Pathol ; 47(2): 189-196, 2018 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29058454

RESUMEN

This study evaluated the antibacterial activity of commercially available organic acid water additives against Salmonella enterica isolates and examined the susceptibility of Salmonella Typhimurium biofilms to these products. Three commercial organic acid products (A, B, and C) were evaluated for minimum inhibitory and bactericidal concentrations against isolates of S. enterica serovars. Three- and five-day-old S. Typhimurium biofilms were formed at 22 ± 2°C using an MBEC™ assay system and exposed for 30 min or 90 min at 0.2% and 0.4% concentrations. No significant difference among serovars for inhibitory and bactericidal concentrations was detected. Two products (A and C) significantly reduced viable cells from biofilms of both ages in a dose- and time-dependent manner. Increased biofilm age did not enhance resistance towards organic acid treatments. None of the products completely eliminated biofilm cells at any concentration or exposure time. Product composition, exposure time, and concentration of organic acid products were important factors in reducing viable biofilm cells. This study has expanded our understanding about the susceptibility of Salmonella biofilms to commercial organic acid products. These findings have implications in the usage, development, and optimization of organic acid products.


Asunto(s)
Biopelículas/efectos de los fármacos , Pollos , Desinfectantes/farmacología , Enfermedades de las Aves de Corral/microbiología , Salmonelosis Animal/microbiología , Salmonella enterica/efectos de los fármacos , Animales , Desinfectantes/química , Granjas , Salmonella enterica/aislamiento & purificación
20.
Vet Res ; 48(1): 5, 2017 02 06.
Artículo en Inglés | MEDLINE | ID: mdl-28166810

RESUMEN

Salmonella Enteriditis and Salmonella Typhimurium are commonly isolated during egg-related outbreaks of salmonellosis and represent a significant international public health issue. In Australia, Salmonella Typhimurium is the most common serovar identified in egg product related foodborne outbreaks. While a number of studies have investigated Salmonella shedding and host responses to infection, they have been conducted over a short time period. The present study sought to characterise bacterial shedding and host responses to infection in hens infected with only Salmonella Typhimurium or co-infected with both Salmonella Typhimurium and Salmonella Mbandaka over a 16 week period. Salmonella shedding was quantified using the most probable number and qPCR methods and was highly variable over the course of the experiment. On day 1, fecal corticosterone metabolites in birds infected with Salmonella Typhimurium (674.2 ± 109.3 pg/mg) were significantly higher than control (238.0 ± 12.62 pg/mg) or co-infected (175.4 ± 8.58 pg/mg) birds. The onset of lay occurred between weeks 6-8 post-infection (pi) and Fecal corticosterone metabolite (FCM) concentrations increased in both control and co-infected birds. Antibody responses to infection were monitored in both serum and yolk samples. Salmonella Typhimurium specific antibody was lower in co-infected animals than monoinfected animals. Bacterial loads in internal organs were characterised to determine persistence. Spleen, liver and caecal tonsils were positive for bacteria in both groups, indicating that Salmonella was not cleared from the birds and internal organ colonization could serve as a reservoir for continued bacterial shedding.


Asunto(s)
Derrame de Bacterias , Corticosterona/análisis , Heces/química , Enfermedades de las Aves de Corral/microbiología , Salmonelosis Animal/microbiología , Salmonella typhimurium , Animales , Pollos/microbiología , Coinfección/microbiología , Coinfección/veterinaria , Corticosterona/fisiología , Heces/microbiología , Femenino , Reacción en Cadena de la Polimerasa/veterinaria , Salmonella , Salmonella typhimurium/fisiología
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