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Frank Pasmans - One of the best experts on this subject based on the ideXlab platform.
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Subtherapeutic tetracycline concentrations aggravate Salmonella typhimurium infection by increasing bacterial virulence
The Journal of antimicrobial chemotherapy, 2016Co-Authors: Elin Verbrugghe, Alexander Van Parys, Roel Haesendonck, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:Objectives: Antibiotics are among the most frequently prescribed drugs in human and animal medicine. With antibiotic resistance being a serious threat to veterinary and public health, the prudent use of antibiotics receives much attention. Lesswell known is that incorrect use of antimicrobial agents mayalso lead to increased bacterial virulence with the potential of a more severe clinical course of infection. Therefore, the aim of this study was to investigate the effect of subtherapeutic doses of tetracyclines on htpG virulence gene expression in Salmonella typhimurium and on the course of salmonellosis. Methods: Salmonella strains containing an htpG-luxCDABE transcriptional fusion were constructed. Phenotype microarrays and tetracycline treatment were used to investigate their htpG expression. A Salmonella transposon mutant bank was used to identify genes involved in the induction of htpG gene expression. Finally, the in vitro results were linked to the in vivo situation using a Salmonella mouse model. Results: We demonstrate that subtherapeutic antimicrobial concentrations can exacerbate bacterial infections through direct up-regulation of bacterial virulence factors using Salmonella typhimurium 112910a phage type 120/ad as a model organism. Phenotype microarrays showed that expression of the Salmonella typhimurium virulence gene htpG is increased by several tetracycline antimicrobials at values below their MIC, a process that requires intact Salmonella LPS genes. Exposure of experimentally infected DBA/2J mice to subtherapeutic doxycycline concentrations resulted in htpG-mediated exacerbation of Salmonella typhimurium infection. Conclusions: These findings show that the Salmonella isolate used in this study can respond to subtherapeutic tetracycline pressure by increasing its virulence and disease severity.
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HtpG contributes to Salmonella typhimurium intestinal persistence in pigs
Veterinary Research, 2015Co-Authors: Elin Verbrugghe, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Alexander Van Parys, Frank PasmansAbstract:Salmonella enterica subspecies enterica serovar typhimurium ( Salmonella typhimurium) contamination of pork, is one of the major sources of human salmonellosis. The bacterium is able to persist and hide in asymptomatic carrier animals, generating a reservoir for Salmonella transmission to other animals and humans. Mechanisms involved in Salmonella persistence in pigs remain poorly understood. In the present study, we demonstrate that the Salmonella htpG gene, encoding a homologue of the eukaryotic heat shock protein 90, contributes to Salmonella typhimurium persistence in intestine-associated tissues of pigs, but not in the tonsils. HtpG does not seem to play an important role during the acute phase of infection. The contribution to persistence was shown to be associated with htpG -dependent Salmonella invasion and survival in porcine enterocytes and macrophages. These results reveal the role of HtpG as a virulence factor contributing to Salmonella persistence in pigs.
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Induction of seroconversion and persistence of Salmonella typhimurium in pigs are strain dependent.
Comparative immunology microbiology and infectious diseases, 2013Co-Authors: Alexander Van Parys, Elin Verbrugghe, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Dominiek Maes, Frank PasmansAbstract:Foodborne salmonellosis is one of the most important bacterial zoonotic diseases worldwide. Salmonella typhimurium is the serovar most frequently isolated from persistently infected slaughter pigs in Europe. Salmonella typhimurium pathogenesis is host species specific. In addition, differences in in vitro behaviour of Salmonella typhimurium strains have also been described, which may be reflected by a different course of infection within a host species. We compared the course of a Salmonella typhimurium infection in pigs, using two Salmonella typhimurium strains that were able to interfere with MHC II expression on porcine macrophages to a different extent in vitro. After experimental inoculation, blood and faecal samples from all pigs were collected at regular time points. At 40 days post inoculation (pi), animals were euthanized and tissue samples were bacteriologically analysed. The proportion of serologically positive piglets at 33 days pi was significantly higher in pigs that were inoculated with the strain that did not downregulate MHC II expression in vitro. Furthermore, this strain was less frequently shed and isolated in lower numbers from tonsils and ileocaecal lymph nodes than the strain that was able to markedly downregulate MHC II expression in vitro. We thus found that the delayed onset of seroconversion after oral inoculation of piglets with a particular Salmonella typhimurium strain coincided with higher faecal shedding and increased persistence. Strain specific differences in Salmonella pathogenesis might thus have repercussions on the serological detection of Salmonella typhimurium infections in pigs.
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Vaccination of pigs reduces Salmonella typhimurium numbers in a model mimicking pre-slaughter stress
Veterinary journal (London England : 1997), 2012Co-Authors: Bregje Leyman, Elin Verbrugghe, Alexander Van Parys, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:In pigs, infection with Salmonella typhimurium often results in the development of carriers that re-excrete the organism during periods of stress. Previous studies have shown that cortisol plays a significant role in the recrudescence of Salmonella typhimurium and that re-excretion can be induced by injections of dexamethasone. This study evaluated whether a commercially available Salmonella typhimurium vaccine was able to reduce Salmonella excretion in a model mimicking pre-slaughter stress. Pigs were randomly assigned to either vaccination or a control group and, 5 weeks later, were infected with Salmonella typhimurium. Twenty-three days post infection, pigs were injected with dexamethasone to induce recrudescence and Salmonella typhimurium numbers were determined. Salmonella loads were significantly lower in the ileum and colon and in the contents of the ileum and caecum in vaccinated pigs than in non-vaccinated pigs. In addition, significantly more Salmonella positive tonsil and colon samples were found in non-vaccinated pigs. Vaccination with an attenuated vaccine reduced but did not eliminate Salmonella typhimurium in pigs in conditions mimicking pre-slaughter stress.
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Salmonella typhimurium interference with the humoral immune response of pigs
International Conference on the Epidemiology and Control of Biological Chemical and Physical Hazards in Pigs and Pork, 2011Co-Authors: Alexander Van Parys, Elin Verbrugghe, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:Foodborne salmonellosis is one of the most important bacterial zoonotic diseases worldwide. Salmonella typhimurium is the serovar most frequently isolated from slaughter pigs in Europe. Circumvention of the host’s immune system by Salmonella might contribute to persistent infection of pigs. We found that Salmonella typhimurium strain 112910a, which is able to persist in pigs, was capable of downregulating the expression of major histocompatibility class II (MHC II) molecules on porcine alveolar macrophages (PAM) in a Salmonella pathogenicity island 2 (SPI-2) dependent way and that MHC II downregulation was Salmonella strain dependent. The MHC II downregulation capacity was abolished when bacteria were opsonized with Salmonella-specific antibodies. Furthermore, intracellular proliferation of Salmonella typhimurium opsonized with Salmonella positive pig serum was significantly impaired compared to that of the bacteria opsonized with negative pig serum. In a subsequent in vivo experiment, Salmonella typhimurium strain MB2216 that did not induce MHC II downregulation in vitro, was shed less and persisted less but induced earlier seroconversion in pigs than strain 112910a. From the in vitro data, it is proposed that Salmonella typhimurium downregulates the humoral immune response to promote intracellular survival inside porcine macrophages, contributing to long-term Salmonella persistence in pigs. The fact that the less persistent strain MB2216 induced earlier seroconversion than strain 112910a is of major interest for Salmonella-monitoring programs primarily based on serology, since this indicates that more persisting strains are more likely to escape serological detection.
Freddy Haesebrouck - One of the best experts on this subject based on the ideXlab platform.
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Subtherapeutic tetracycline concentrations aggravate Salmonella typhimurium infection by increasing bacterial virulence
The Journal of antimicrobial chemotherapy, 2016Co-Authors: Elin Verbrugghe, Alexander Van Parys, Roel Haesendonck, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:Objectives: Antibiotics are among the most frequently prescribed drugs in human and animal medicine. With antibiotic resistance being a serious threat to veterinary and public health, the prudent use of antibiotics receives much attention. Lesswell known is that incorrect use of antimicrobial agents mayalso lead to increased bacterial virulence with the potential of a more severe clinical course of infection. Therefore, the aim of this study was to investigate the effect of subtherapeutic doses of tetracyclines on htpG virulence gene expression in Salmonella typhimurium and on the course of salmonellosis. Methods: Salmonella strains containing an htpG-luxCDABE transcriptional fusion were constructed. Phenotype microarrays and tetracycline treatment were used to investigate their htpG expression. A Salmonella transposon mutant bank was used to identify genes involved in the induction of htpG gene expression. Finally, the in vitro results were linked to the in vivo situation using a Salmonella mouse model. Results: We demonstrate that subtherapeutic antimicrobial concentrations can exacerbate bacterial infections through direct up-regulation of bacterial virulence factors using Salmonella typhimurium 112910a phage type 120/ad as a model organism. Phenotype microarrays showed that expression of the Salmonella typhimurium virulence gene htpG is increased by several tetracycline antimicrobials at values below their MIC, a process that requires intact Salmonella LPS genes. Exposure of experimentally infected DBA/2J mice to subtherapeutic doxycycline concentrations resulted in htpG-mediated exacerbation of Salmonella typhimurium infection. Conclusions: These findings show that the Salmonella isolate used in this study can respond to subtherapeutic tetracycline pressure by increasing its virulence and disease severity.
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HtpG contributes to Salmonella typhimurium intestinal persistence in pigs
Veterinary Research, 2015Co-Authors: Elin Verbrugghe, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Alexander Van Parys, Frank PasmansAbstract:Salmonella enterica subspecies enterica serovar typhimurium ( Salmonella typhimurium) contamination of pork, is one of the major sources of human salmonellosis. The bacterium is able to persist and hide in asymptomatic carrier animals, generating a reservoir for Salmonella transmission to other animals and humans. Mechanisms involved in Salmonella persistence in pigs remain poorly understood. In the present study, we demonstrate that the Salmonella htpG gene, encoding a homologue of the eukaryotic heat shock protein 90, contributes to Salmonella typhimurium persistence in intestine-associated tissues of pigs, but not in the tonsils. HtpG does not seem to play an important role during the acute phase of infection. The contribution to persistence was shown to be associated with htpG -dependent Salmonella invasion and survival in porcine enterocytes and macrophages. These results reveal the role of HtpG as a virulence factor contributing to Salmonella persistence in pigs.
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Oral administration of the Salmonella typhimurium vaccine strain Nal2/Rif9/Rtt to laying hens at day of hatch reduces shedding and caecal colonization of Salmonella 4,12:i:-, the monophasic variant of Salmonella typhimurium
Poultry science, 2015Co-Authors: Sofie Kilroy, Freddy Haesebrouck, Ruth Raspoet, Rosalie Devloo, Richard Ducatelle, Filip Van ImmerseelAbstract:A new monophasic variant of Salmonella typhimurium, Salmonella enterica serotype 4,12:i:-, is rapidly emerging. This serotype is now considered to be among the 10 most common serovars isolated from humans in many countries in Europe and in the United States. The public health risk posed by these emerging monophasic Salmonella typhimurium strains is considered comparable to that of classical Salmonella typhimurium strains. The serotype 4,12:i:- is frequently isolated from pigs but also poultry are carrying strains from this serotype. In the current study, we evaluated the efficacy of the Salmonella typhimurium strain Nal2/Rif9/Rtt, a strain contained in the commercially available live vaccines AviPro Salmonella Duo and AviPro Salmonella VacT, against infection with the emerging monophasic variant in poultry. Three independent trials were conducted. In all trials, laying type chicks were orally vaccinated with the Salmonella typhimurium strain Nal2/Rif9/Rtt at d hatch, while the birds were challenged the next d with a different infection dose in each trial (low, high, and intermediate). For the intermediate-dose study, a seeder bird model was used in which one out of 3 animals were infected while all individual birds were infected in the other trials. Data obtained from each independent trial show that oral administration of the Salmonella typhimurium strain Nal2/Rif9/Rtt at d hatch reduced shedding, caecal, and internal organ colonization of Salmonella typhimurium 4,12:i:-, administered at d 2 life. This indicates that Salmonella typhimurium strain Nal2/Rif9/Rtt can help to control Salmonella 4,12:i:- infections in poultry.
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Induction of seroconversion and persistence of Salmonella typhimurium in pigs are strain dependent.
Comparative immunology microbiology and infectious diseases, 2013Co-Authors: Alexander Van Parys, Elin Verbrugghe, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Dominiek Maes, Frank PasmansAbstract:Foodborne salmonellosis is one of the most important bacterial zoonotic diseases worldwide. Salmonella typhimurium is the serovar most frequently isolated from persistently infected slaughter pigs in Europe. Salmonella typhimurium pathogenesis is host species specific. In addition, differences in in vitro behaviour of Salmonella typhimurium strains have also been described, which may be reflected by a different course of infection within a host species. We compared the course of a Salmonella typhimurium infection in pigs, using two Salmonella typhimurium strains that were able to interfere with MHC II expression on porcine macrophages to a different extent in vitro. After experimental inoculation, blood and faecal samples from all pigs were collected at regular time points. At 40 days post inoculation (pi), animals were euthanized and tissue samples were bacteriologically analysed. The proportion of serologically positive piglets at 33 days pi was significantly higher in pigs that were inoculated with the strain that did not downregulate MHC II expression in vitro. Furthermore, this strain was less frequently shed and isolated in lower numbers from tonsils and ileocaecal lymph nodes than the strain that was able to markedly downregulate MHC II expression in vitro. We thus found that the delayed onset of seroconversion after oral inoculation of piglets with a particular Salmonella typhimurium strain coincided with higher faecal shedding and increased persistence. Strain specific differences in Salmonella pathogenesis might thus have repercussions on the serological detection of Salmonella typhimurium infections in pigs.
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Vaccination of pigs reduces Salmonella typhimurium numbers in a model mimicking pre-slaughter stress
Veterinary journal (London England : 1997), 2012Co-Authors: Bregje Leyman, Elin Verbrugghe, Alexander Van Parys, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:In pigs, infection with Salmonella typhimurium often results in the development of carriers that re-excrete the organism during periods of stress. Previous studies have shown that cortisol plays a significant role in the recrudescence of Salmonella typhimurium and that re-excretion can be induced by injections of dexamethasone. This study evaluated whether a commercially available Salmonella typhimurium vaccine was able to reduce Salmonella excretion in a model mimicking pre-slaughter stress. Pigs were randomly assigned to either vaccination or a control group and, 5 weeks later, were infected with Salmonella typhimurium. Twenty-three days post infection, pigs were injected with dexamethasone to induce recrudescence and Salmonella typhimurium numbers were determined. Salmonella loads were significantly lower in the ileum and colon and in the contents of the ileum and caecum in vaccinated pigs than in non-vaccinated pigs. In addition, significantly more Salmonella positive tonsil and colon samples were found in non-vaccinated pigs. Vaccination with an attenuated vaccine reduced but did not eliminate Salmonella typhimurium in pigs in conditions mimicking pre-slaughter stress.
Filip Boyen - One of the best experts on this subject based on the ideXlab platform.
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Subtherapeutic tetracycline concentrations aggravate Salmonella typhimurium infection by increasing bacterial virulence
The Journal of antimicrobial chemotherapy, 2016Co-Authors: Elin Verbrugghe, Alexander Van Parys, Roel Haesendonck, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:Objectives: Antibiotics are among the most frequently prescribed drugs in human and animal medicine. With antibiotic resistance being a serious threat to veterinary and public health, the prudent use of antibiotics receives much attention. Lesswell known is that incorrect use of antimicrobial agents mayalso lead to increased bacterial virulence with the potential of a more severe clinical course of infection. Therefore, the aim of this study was to investigate the effect of subtherapeutic doses of tetracyclines on htpG virulence gene expression in Salmonella typhimurium and on the course of salmonellosis. Methods: Salmonella strains containing an htpG-luxCDABE transcriptional fusion were constructed. Phenotype microarrays and tetracycline treatment were used to investigate their htpG expression. A Salmonella transposon mutant bank was used to identify genes involved in the induction of htpG gene expression. Finally, the in vitro results were linked to the in vivo situation using a Salmonella mouse model. Results: We demonstrate that subtherapeutic antimicrobial concentrations can exacerbate bacterial infections through direct up-regulation of bacterial virulence factors using Salmonella typhimurium 112910a phage type 120/ad as a model organism. Phenotype microarrays showed that expression of the Salmonella typhimurium virulence gene htpG is increased by several tetracycline antimicrobials at values below their MIC, a process that requires intact Salmonella LPS genes. Exposure of experimentally infected DBA/2J mice to subtherapeutic doxycycline concentrations resulted in htpG-mediated exacerbation of Salmonella typhimurium infection. Conclusions: These findings show that the Salmonella isolate used in this study can respond to subtherapeutic tetracycline pressure by increasing its virulence and disease severity.
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HtpG contributes to Salmonella typhimurium intestinal persistence in pigs
Veterinary Research, 2015Co-Authors: Elin Verbrugghe, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Alexander Van Parys, Frank PasmansAbstract:Salmonella enterica subspecies enterica serovar typhimurium ( Salmonella typhimurium) contamination of pork, is one of the major sources of human salmonellosis. The bacterium is able to persist and hide in asymptomatic carrier animals, generating a reservoir for Salmonella transmission to other animals and humans. Mechanisms involved in Salmonella persistence in pigs remain poorly understood. In the present study, we demonstrate that the Salmonella htpG gene, encoding a homologue of the eukaryotic heat shock protein 90, contributes to Salmonella typhimurium persistence in intestine-associated tissues of pigs, but not in the tonsils. HtpG does not seem to play an important role during the acute phase of infection. The contribution to persistence was shown to be associated with htpG -dependent Salmonella invasion and survival in porcine enterocytes and macrophages. These results reveal the role of HtpG as a virulence factor contributing to Salmonella persistence in pigs.
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Induction of seroconversion and persistence of Salmonella typhimurium in pigs are strain dependent.
Comparative immunology microbiology and infectious diseases, 2013Co-Authors: Alexander Van Parys, Elin Verbrugghe, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Dominiek Maes, Frank PasmansAbstract:Foodborne salmonellosis is one of the most important bacterial zoonotic diseases worldwide. Salmonella typhimurium is the serovar most frequently isolated from persistently infected slaughter pigs in Europe. Salmonella typhimurium pathogenesis is host species specific. In addition, differences in in vitro behaviour of Salmonella typhimurium strains have also been described, which may be reflected by a different course of infection within a host species. We compared the course of a Salmonella typhimurium infection in pigs, using two Salmonella typhimurium strains that were able to interfere with MHC II expression on porcine macrophages to a different extent in vitro. After experimental inoculation, blood and faecal samples from all pigs were collected at regular time points. At 40 days post inoculation (pi), animals were euthanized and tissue samples were bacteriologically analysed. The proportion of serologically positive piglets at 33 days pi was significantly higher in pigs that were inoculated with the strain that did not downregulate MHC II expression in vitro. Furthermore, this strain was less frequently shed and isolated in lower numbers from tonsils and ileocaecal lymph nodes than the strain that was able to markedly downregulate MHC II expression in vitro. We thus found that the delayed onset of seroconversion after oral inoculation of piglets with a particular Salmonella typhimurium strain coincided with higher faecal shedding and increased persistence. Strain specific differences in Salmonella pathogenesis might thus have repercussions on the serological detection of Salmonella typhimurium infections in pigs.
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Vaccination of pigs reduces Salmonella typhimurium numbers in a model mimicking pre-slaughter stress
Veterinary journal (London England : 1997), 2012Co-Authors: Bregje Leyman, Elin Verbrugghe, Alexander Van Parys, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:In pigs, infection with Salmonella typhimurium often results in the development of carriers that re-excrete the organism during periods of stress. Previous studies have shown that cortisol plays a significant role in the recrudescence of Salmonella typhimurium and that re-excretion can be induced by injections of dexamethasone. This study evaluated whether a commercially available Salmonella typhimurium vaccine was able to reduce Salmonella excretion in a model mimicking pre-slaughter stress. Pigs were randomly assigned to either vaccination or a control group and, 5 weeks later, were infected with Salmonella typhimurium. Twenty-three days post infection, pigs were injected with dexamethasone to induce recrudescence and Salmonella typhimurium numbers were determined. Salmonella loads were significantly lower in the ileum and colon and in the contents of the ileum and caecum in vaccinated pigs than in non-vaccinated pigs. In addition, significantly more Salmonella positive tonsil and colon samples were found in non-vaccinated pigs. Vaccination with an attenuated vaccine reduced but did not eliminate Salmonella typhimurium in pigs in conditions mimicking pre-slaughter stress.
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The Mycotoxin Deoxynivalenol Potentiates Intestinal Inflammation by Salmonella typhimurium in Porcine Ileal Loops
PloS one, 2011Co-Authors: Virginie Vandenbroucke, Elin Verbrugghe, Filip Boyen, Siska Croubels, Joline Goossens, Arthur Thompson, Neil Shearer, An Martel, Kim Van Deun, Patrick De BackerAbstract:Background and Aims Both deoxynivalenol (DON) and nontyphoidal salmonellosis are emerging threats with possible hazardous effects on both human and animal health. The objective of this study was to examine whether DON at low but relevant concentrations interacts with the intestinal inflammation induced by Salmonella typhimurium. Methodology By using a porcine intestinal ileal loop model, we investigated whether intake of low concentrations of DON interacts with the early intestinal inflammatory response induced by Salmonella typhimurium. Results A significant higher expression of IL-12 and TNFα and a clear potentiation of the expression of IL-1β, IL-8, MCP-1 and IL-6 was seen in loops co-exposed to 1 µg/mL of DON and Salmonella typhimurium compared to loops exposed to Salmonella typhimurium alone. This potentiation coincided with a significantly enhanced Salmonella invasion in and translocation over the intestinal epithelial IPEC-J2 cells, exposed to non-cytotoxic concentrations of DON for 24 h. Exposure of Salmonella typhimurium to 0.250 µg/mL of DON affected the bacterial gene expression level of a limited number of genes, however none of these expression changes seemed to give an explanation for the increased invasion and translocation of Salmonella typhimurium and the potentiated inflammatory response in combination with DON. Conclusion These data imply that the intake of low and relevant concentrations of DON renders the intestinal epithelium more susceptible to Salmonella typhimurium with a subsequent potentiation of the inflammatory response in the gut.
Elin Verbrugghe - One of the best experts on this subject based on the ideXlab platform.
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Subtherapeutic tetracycline concentrations aggravate Salmonella typhimurium infection by increasing bacterial virulence
The Journal of antimicrobial chemotherapy, 2016Co-Authors: Elin Verbrugghe, Alexander Van Parys, Roel Haesendonck, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:Objectives: Antibiotics are among the most frequently prescribed drugs in human and animal medicine. With antibiotic resistance being a serious threat to veterinary and public health, the prudent use of antibiotics receives much attention. Lesswell known is that incorrect use of antimicrobial agents mayalso lead to increased bacterial virulence with the potential of a more severe clinical course of infection. Therefore, the aim of this study was to investigate the effect of subtherapeutic doses of tetracyclines on htpG virulence gene expression in Salmonella typhimurium and on the course of salmonellosis. Methods: Salmonella strains containing an htpG-luxCDABE transcriptional fusion were constructed. Phenotype microarrays and tetracycline treatment were used to investigate their htpG expression. A Salmonella transposon mutant bank was used to identify genes involved in the induction of htpG gene expression. Finally, the in vitro results were linked to the in vivo situation using a Salmonella mouse model. Results: We demonstrate that subtherapeutic antimicrobial concentrations can exacerbate bacterial infections through direct up-regulation of bacterial virulence factors using Salmonella typhimurium 112910a phage type 120/ad as a model organism. Phenotype microarrays showed that expression of the Salmonella typhimurium virulence gene htpG is increased by several tetracycline antimicrobials at values below their MIC, a process that requires intact Salmonella LPS genes. Exposure of experimentally infected DBA/2J mice to subtherapeutic doxycycline concentrations resulted in htpG-mediated exacerbation of Salmonella typhimurium infection. Conclusions: These findings show that the Salmonella isolate used in this study can respond to subtherapeutic tetracycline pressure by increasing its virulence and disease severity.
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HtpG contributes to Salmonella typhimurium intestinal persistence in pigs
Veterinary Research, 2015Co-Authors: Elin Verbrugghe, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Alexander Van Parys, Frank PasmansAbstract:Salmonella enterica subspecies enterica serovar typhimurium ( Salmonella typhimurium) contamination of pork, is one of the major sources of human salmonellosis. The bacterium is able to persist and hide in asymptomatic carrier animals, generating a reservoir for Salmonella transmission to other animals and humans. Mechanisms involved in Salmonella persistence in pigs remain poorly understood. In the present study, we demonstrate that the Salmonella htpG gene, encoding a homologue of the eukaryotic heat shock protein 90, contributes to Salmonella typhimurium persistence in intestine-associated tissues of pigs, but not in the tonsils. HtpG does not seem to play an important role during the acute phase of infection. The contribution to persistence was shown to be associated with htpG -dependent Salmonella invasion and survival in porcine enterocytes and macrophages. These results reveal the role of HtpG as a virulence factor contributing to Salmonella persistence in pigs.
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Induction of seroconversion and persistence of Salmonella typhimurium in pigs are strain dependent.
Comparative immunology microbiology and infectious diseases, 2013Co-Authors: Alexander Van Parys, Elin Verbrugghe, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Dominiek Maes, Frank PasmansAbstract:Foodborne salmonellosis is one of the most important bacterial zoonotic diseases worldwide. Salmonella typhimurium is the serovar most frequently isolated from persistently infected slaughter pigs in Europe. Salmonella typhimurium pathogenesis is host species specific. In addition, differences in in vitro behaviour of Salmonella typhimurium strains have also been described, which may be reflected by a different course of infection within a host species. We compared the course of a Salmonella typhimurium infection in pigs, using two Salmonella typhimurium strains that were able to interfere with MHC II expression on porcine macrophages to a different extent in vitro. After experimental inoculation, blood and faecal samples from all pigs were collected at regular time points. At 40 days post inoculation (pi), animals were euthanized and tissue samples were bacteriologically analysed. The proportion of serologically positive piglets at 33 days pi was significantly higher in pigs that were inoculated with the strain that did not downregulate MHC II expression in vitro. Furthermore, this strain was less frequently shed and isolated in lower numbers from tonsils and ileocaecal lymph nodes than the strain that was able to markedly downregulate MHC II expression in vitro. We thus found that the delayed onset of seroconversion after oral inoculation of piglets with a particular Salmonella typhimurium strain coincided with higher faecal shedding and increased persistence. Strain specific differences in Salmonella pathogenesis might thus have repercussions on the serological detection of Salmonella typhimurium infections in pigs.
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Vaccination of pigs reduces Salmonella typhimurium numbers in a model mimicking pre-slaughter stress
Veterinary journal (London England : 1997), 2012Co-Authors: Bregje Leyman, Elin Verbrugghe, Alexander Van Parys, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:In pigs, infection with Salmonella typhimurium often results in the development of carriers that re-excrete the organism during periods of stress. Previous studies have shown that cortisol plays a significant role in the recrudescence of Salmonella typhimurium and that re-excretion can be induced by injections of dexamethasone. This study evaluated whether a commercially available Salmonella typhimurium vaccine was able to reduce Salmonella excretion in a model mimicking pre-slaughter stress. Pigs were randomly assigned to either vaccination or a control group and, 5 weeks later, were infected with Salmonella typhimurium. Twenty-three days post infection, pigs were injected with dexamethasone to induce recrudescence and Salmonella typhimurium numbers were determined. Salmonella loads were significantly lower in the ileum and colon and in the contents of the ileum and caecum in vaccinated pigs than in non-vaccinated pigs. In addition, significantly more Salmonella positive tonsil and colon samples were found in non-vaccinated pigs. Vaccination with an attenuated vaccine reduced but did not eliminate Salmonella typhimurium in pigs in conditions mimicking pre-slaughter stress.
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The Mycotoxin Deoxynivalenol Potentiates Intestinal Inflammation by Salmonella typhimurium in Porcine Ileal Loops
PloS one, 2011Co-Authors: Virginie Vandenbroucke, Elin Verbrugghe, Filip Boyen, Siska Croubels, Joline Goossens, Arthur Thompson, Neil Shearer, An Martel, Kim Van Deun, Patrick De BackerAbstract:Background and Aims Both deoxynivalenol (DON) and nontyphoidal salmonellosis are emerging threats with possible hazardous effects on both human and animal health. The objective of this study was to examine whether DON at low but relevant concentrations interacts with the intestinal inflammation induced by Salmonella typhimurium. Methodology By using a porcine intestinal ileal loop model, we investigated whether intake of low concentrations of DON interacts with the early intestinal inflammatory response induced by Salmonella typhimurium. Results A significant higher expression of IL-12 and TNFα and a clear potentiation of the expression of IL-1β, IL-8, MCP-1 and IL-6 was seen in loops co-exposed to 1 µg/mL of DON and Salmonella typhimurium compared to loops exposed to Salmonella typhimurium alone. This potentiation coincided with a significantly enhanced Salmonella invasion in and translocation over the intestinal epithelial IPEC-J2 cells, exposed to non-cytotoxic concentrations of DON for 24 h. Exposure of Salmonella typhimurium to 0.250 µg/mL of DON affected the bacterial gene expression level of a limited number of genes, however none of these expression changes seemed to give an explanation for the increased invasion and translocation of Salmonella typhimurium and the potentiated inflammatory response in combination with DON. Conclusion These data imply that the intake of low and relevant concentrations of DON renders the intestinal epithelium more susceptible to Salmonella typhimurium with a subsequent potentiation of the inflammatory response in the gut.
Alexander Van Parys - One of the best experts on this subject based on the ideXlab platform.
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Subtherapeutic tetracycline concentrations aggravate Salmonella typhimurium infection by increasing bacterial virulence
The Journal of antimicrobial chemotherapy, 2016Co-Authors: Elin Verbrugghe, Alexander Van Parys, Roel Haesendonck, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:Objectives: Antibiotics are among the most frequently prescribed drugs in human and animal medicine. With antibiotic resistance being a serious threat to veterinary and public health, the prudent use of antibiotics receives much attention. Lesswell known is that incorrect use of antimicrobial agents mayalso lead to increased bacterial virulence with the potential of a more severe clinical course of infection. Therefore, the aim of this study was to investigate the effect of subtherapeutic doses of tetracyclines on htpG virulence gene expression in Salmonella typhimurium and on the course of salmonellosis. Methods: Salmonella strains containing an htpG-luxCDABE transcriptional fusion were constructed. Phenotype microarrays and tetracycline treatment were used to investigate their htpG expression. A Salmonella transposon mutant bank was used to identify genes involved in the induction of htpG gene expression. Finally, the in vitro results were linked to the in vivo situation using a Salmonella mouse model. Results: We demonstrate that subtherapeutic antimicrobial concentrations can exacerbate bacterial infections through direct up-regulation of bacterial virulence factors using Salmonella typhimurium 112910a phage type 120/ad as a model organism. Phenotype microarrays showed that expression of the Salmonella typhimurium virulence gene htpG is increased by several tetracycline antimicrobials at values below their MIC, a process that requires intact Salmonella LPS genes. Exposure of experimentally infected DBA/2J mice to subtherapeutic doxycycline concentrations resulted in htpG-mediated exacerbation of Salmonella typhimurium infection. Conclusions: These findings show that the Salmonella isolate used in this study can respond to subtherapeutic tetracycline pressure by increasing its virulence and disease severity.
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Induction of seroconversion and persistence of Salmonella typhimurium in pigs are strain dependent.
Comparative immunology microbiology and infectious diseases, 2013Co-Authors: Alexander Van Parys, Elin Verbrugghe, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Dominiek Maes, Frank PasmansAbstract:Foodborne salmonellosis is one of the most important bacterial zoonotic diseases worldwide. Salmonella typhimurium is the serovar most frequently isolated from persistently infected slaughter pigs in Europe. Salmonella typhimurium pathogenesis is host species specific. In addition, differences in in vitro behaviour of Salmonella typhimurium strains have also been described, which may be reflected by a different course of infection within a host species. We compared the course of a Salmonella typhimurium infection in pigs, using two Salmonella typhimurium strains that were able to interfere with MHC II expression on porcine macrophages to a different extent in vitro. After experimental inoculation, blood and faecal samples from all pigs were collected at regular time points. At 40 days post inoculation (pi), animals were euthanized and tissue samples were bacteriologically analysed. The proportion of serologically positive piglets at 33 days pi was significantly higher in pigs that were inoculated with the strain that did not downregulate MHC II expression in vitro. Furthermore, this strain was less frequently shed and isolated in lower numbers from tonsils and ileocaecal lymph nodes than the strain that was able to markedly downregulate MHC II expression in vitro. We thus found that the delayed onset of seroconversion after oral inoculation of piglets with a particular Salmonella typhimurium strain coincided with higher faecal shedding and increased persistence. Strain specific differences in Salmonella pathogenesis might thus have repercussions on the serological detection of Salmonella typhimurium infections in pigs.
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Vaccination of pigs reduces Salmonella typhimurium numbers in a model mimicking pre-slaughter stress
Veterinary journal (London England : 1997), 2012Co-Authors: Bregje Leyman, Elin Verbrugghe, Alexander Van Parys, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:In pigs, infection with Salmonella typhimurium often results in the development of carriers that re-excrete the organism during periods of stress. Previous studies have shown that cortisol plays a significant role in the recrudescence of Salmonella typhimurium and that re-excretion can be induced by injections of dexamethasone. This study evaluated whether a commercially available Salmonella typhimurium vaccine was able to reduce Salmonella excretion in a model mimicking pre-slaughter stress. Pigs were randomly assigned to either vaccination or a control group and, 5 weeks later, were infected with Salmonella typhimurium. Twenty-three days post infection, pigs were injected with dexamethasone to induce recrudescence and Salmonella typhimurium numbers were determined. Salmonella loads were significantly lower in the ileum and colon and in the contents of the ileum and caecum in vaccinated pigs than in non-vaccinated pigs. In addition, significantly more Salmonella positive tonsil and colon samples were found in non-vaccinated pigs. Vaccination with an attenuated vaccine reduced but did not eliminate Salmonella typhimurium in pigs in conditions mimicking pre-slaughter stress.
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Salmonella typhimurium interference with the humoral immune response of pigs
International Conference on the Epidemiology and Control of Biological Chemical and Physical Hazards in Pigs and Pork, 2011Co-Authors: Alexander Van Parys, Elin Verbrugghe, Bregje Leyman, Filip Boyen, Freddy Haesebrouck, Frank PasmansAbstract:Foodborne salmonellosis is one of the most important bacterial zoonotic diseases worldwide. Salmonella typhimurium is the serovar most frequently isolated from slaughter pigs in Europe. Circumvention of the host’s immune system by Salmonella might contribute to persistent infection of pigs. We found that Salmonella typhimurium strain 112910a, which is able to persist in pigs, was capable of downregulating the expression of major histocompatibility class II (MHC II) molecules on porcine alveolar macrophages (PAM) in a Salmonella pathogenicity island 2 (SPI-2) dependent way and that MHC II downregulation was Salmonella strain dependent. The MHC II downregulation capacity was abolished when bacteria were opsonized with Salmonella-specific antibodies. Furthermore, intracellular proliferation of Salmonella typhimurium opsonized with Salmonella positive pig serum was significantly impaired compared to that of the bacteria opsonized with negative pig serum. In a subsequent in vivo experiment, Salmonella typhimurium strain MB2216 that did not induce MHC II downregulation in vitro, was shed less and persisted less but induced earlier seroconversion in pigs than strain 112910a. From the in vitro data, it is proposed that Salmonella typhimurium downregulates the humoral immune response to promote intracellular survival inside porcine macrophages, contributing to long-term Salmonella persistence in pigs. The fact that the less persistent strain MB2216 induced earlier seroconversion than strain 112910a is of major interest for Salmonella-monitoring programs primarily based on serology, since this indicates that more persisting strains are more likely to escape serological detection.
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The use of tannins to control Salmonella typhimurium infections in pigs.
Zoonoses and public health, 2010Co-Authors: Alexander Van Parys, Filip Boyen, Freddy Haesebrouck, Jeroen Dewulf, Frank PasmansAbstract:The aim of this study was to determine whether a hydrolysable tannin extract of sweet chestnut wood (Globatan (R)) has an inhibitory effect on Salmonella typhimurium survival both in vitro and in vivo in pigs. In a first experiment, the minimal inhibitory concentration of Globatan (R) on 57 Salmonella typhimurium isolates was determined. For all isolates, an MIC of 160-320 mu g/ml was found. The second in vitro study revealed that Salmonella growth was strongly reduced using Globatan (R) concentrations of 25-50 mu g/ml and nearly completely inhibited at a concentration of 100 mu g/ml Globatan (R). In an in vivo trial, two groups of six piglets, each group receiving feed with or without the addition of Globatan (R) (3 g/kg), were orally inoculated with 107 colony forming units of a Salmonella typhimurium strain. Globatan (R) had no effect on faecal excretion of Salmonella, and no differences in colonization of the intestines and internal organs were demonstrated in pigs euthanized at 4 days post-inoculation. In conclusion, the hydrolysable tannin extract used in this study showed strong action against Salmonella typhimurium in vitro but not in vivo.
