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F Pasmans

Publications and source records attributed to F Pasmans.

28 records · Page 2Linked to original sources
PubMed2004

Medium-chain fatty acids decrease colonization and invasion through hilA suppression shortly after infection of chickens with Salmonella enterica serovar Enteritidis.

The most common source of Salmonella infections in humans is food of poultry origin. Salmonella enterica serovar Enteritidis has a particular affinity for the contamination of the egg supply. In this study, the medium-chain fatty acids (MCFA), caproic, caprylic, and capric acid, were evaluated for the control of Salmonella serovar Enteritidis in chickens. All MCFA were growth inhibiting at low concentrations in vitro, with caproic acid being the most potent. Contact of Salmonella serovar Enteritidis with low concentrations of MCFA decreased invasion in the intestinal epithelial cell line T84. By using transcriptional fusions between the promoter of the regulatory gene of the Salmonella pathogenicity island I, hilA, and luxCDABE genes, it was shown that all MCFA decreased the expression of hilA, a key regulator related to the invasive capacity of Salmonella. The addition of caproic acid (3 g/kg of feed) to the feed of chicks led to a significant decrease in the level of colonization of ceca and internal organs by Salmonella serovar Enteritidis at 3 days after infection of 5-day-old chicks. These results suggest that MCFA have a synergistic ability to suppress the expression of the genes required for invasion and to reduce the numbers of bacteria in vivo. Thus, MCFA are potentially useful products for reducing the level of colonization of chicks and could ultimately aid in the reduction of the number of contaminated eggs in the food supply.

Animals↗
PubMed2003

Invasion of Salmonella enteritidis in avian intestinal epithelial cells in vitro is influenced by short-chain fatty acids.

Fermentation reactions in the caeca of chickens, the predominant place for Salmonella colonization, result in high concentrations of short-chain fatty acids (SCFA). Thus Salmonella bacteria are in close contact with SCFA during their life cycle. A study was carried out to analyse the effects of SCFA on invasion of Salmonella enteritidis in an avian intestinal epithelial cell line. Preincubation of S. enteritidis for 4 h in growth media supplemented with various concentrations of propionate or butyrate resulted in decreased invasion compared to bacteria, preincubated in nonsupplemented media, and to bacteria, preincubated in media supplemented with formate or acetate. Incubation of the S. enteritidis bacteria in media supplemented with mixtures of SCFA mimicking the in vivo caecal concentrations resulted in increased invasion compared with butyrate-exposed bacteria, but equal invasion compared with nonexposed bacteria. Increasing the butyrate concentration in these mixtures did not modify invasion compared with the original mixtures.

Animals↗
PubMed2003

Flavobacterium psychrophilum infections in salmonid fish.

Flavobacterium psychrophilum is the causative agent of bacterial cold water disease and rainbow trout fry syndrome, disease entities responsible for substantial economic losses in salmonid aquaculture. Problems associated with epizootics include high mortality rate, increased susceptibility to other diseases, high labour costs of treatment and the enormous expenditure on chemotherapy. Despite the increasing significance of the disease, the pathogenesis of F. psychrophilum infections has only been partially elucidated, hampering the development of preventive measures to efficiently combat this disease condition. This literature review discusses the agent and the disease it causes, with emphasis on the bacterium-host interactions.

Animals↗
PubMed2003

First report on Cryptococcus laurentii associated with feather loss in a glossy starling (Lamprotornis chalybaeus).

Although Cryptococcus laurentii has been isolated from fresh droppings and cloaca samples from feral pigeons, it has never before been associated with an actual disease condition in birds. This case study deals with the first report on C. laurentii associated with feather loss in a glossy starling (Lamprotornis chalybaeus). The bird exhibited patchy feather loss, especially around the back and beak area, and greyish crusts sticking quite firmly to the underlying skin. The feathers had a greasy appearance and disseminated a musty odour. Treatment was installed with fluconazole in the drinking water. One month following the onset of treatment, the condition of the plumage had markedly improved.

Animals↗
PubMed2002

Interactions of Salmonella enterica serovar Muenchen with macrophages of the turtle Trachemys scripta scripta.

Interactions of Salmonella with macrophages have been studied in birds and, most extensively, in mammals. In these homeothermic animals, interactions between Salmonella and macrophages are characterized by the following processes. After macropinocytosis, spacious phagosomes are formed within the macrophage. Partial inhibition of phagosome-lysosome fusion and resistance to the formation of reactive oxygen species and reactive nitrogen intermediates enable the bacterium to survive and even multiply within the host macrophage. Eventually, Salmonella will induce apoptosis of the macrophage. In this study, interactions of peritoneal macrophages of the turtle Trachemys scripta scripta with Salmonella enterica serovar Muenchen were examined in vitro. Turtle macrophages were able to phagocytise Salmonella efficiently at both 30 and 37 degrees C. Exposure of macrophages to Salmonella induced the production of reactive oxygen species, which could be partially suppressed by adding the NADPH oxidase inhibitor diphenylene iodonium. Initially, most of the intracellular bacteria were killed. However, Salmonella proved to be able to persist and multiply inside turtle macrophages at both 30 and 37 degrees C for at least 48 h, despite the production of reactive nitrogen intermediates by inducible NO synthase. Salmonella infection of turtle macrophages killed the phagocytes at both 30 and 37 degrees C. These findings demonstrate that no obvious qualitative differences exist between macrophage-Salmonella interactions from homeothermic animals and from turtles. This indicates that other factors are responsible for the different course of Salmonella infections in homeothermic and poikilothermic hosts.

Animals↗
PubMed2001

Induction of the respiratory burst in turtle peritoneal macrophages by Salmonella muenchen.

Peritoneal macrophages were collected from juvenile turtles 72h after intraperitoneal inoculation with a 3% Sephadex suspension. The macrophages were assayed for their chemiluminescent (CL) properties, reflecting their respiratory burst activity, after stimulation with Zymosan A, phorbol 12-myristate 13-acetate (PMA), N-formyl-methionyl-leucyl-phenylalanine (fMLP), and calcium ionophore A23187. Except for fMLP, all triggering agents induced a marked CL response. Luminol was used as the chemiluminescent probe. When comparing CL responses in temperatures ranging from 15 to 35 degrees C, lower assay temperatures induced lower and slower CL responses. Stimulation with viable Salmonella muenchen resulted in a distinct response. Bacteria, inactivated by means of heat or acetone, induced a faster and stronger oxidative burst. Opsonization of either viable or heat-inactivated S. muenchen with non-inactivated anti-S. muenchen serum, prepared in turtles, induced faster and higher CL responses. On the other hand, opsonization of acetone-inactivated S. muenchen caused CL responses to be slower and weaker. S. muenchen, opsonized with heat-inactivated turtle anti S. muenchen serum, induced higher responses than non-opsonized bacteria, but slower and weaker responses than bacteria opsonized with native turtle antiserum. No response was recorded after stimulation with LPS and the supernatant of heat-inactivated bacteria.

Acetone↗
PubMedDate not supplied

Interactions of Salmonella enterica subsp. enterica serovar Muenchen with intestinal explants of the turtle Trachemys scripta scripta.

Salmonella infections in reptiles, in contrast to those in birds and mammals, are limited to the intestinal tract. In this study, interactions of a strain of Salmonella enterica subsp. enterica serovar Muenchen (SEEM) with intestinal explants of the turtle Trachemys scripta scripta were examined by scanning electron microscopy (SEM). Adhesion and invasion in the chelonian intestinal explants at 30 degrees C and 37 degrees C were evaluated quantitatively. For purposes of comparison, the invasive capacity of SEEM in the continuous avian epithelial cell line DIV-1 at 30 degrees C and 37 degrees C was determined. Small numbers of M-like cells were found in the ileum of the turtles. The bacteria adhered mainly to the mucus of the intestinal explants. Only small numbers of salmonellae were associated with epithelial cells. Higher numbers of bacteria adhered at 30 degrees C than at 37 degrees C. Epithelial damage, embedding of bacteria in the epithelial surface and a ruffling-like process were noted only at 37 degrees C. Minimal numbers of salmonellae invaded the explants at 30 degrees C and 37 degrees C. Invasion of DIV-1 cells was greater at 37 degrees C than at 30 degrees C. The study suggested that the intestinal mucous layer provides an important site of colonization for salmonellae in the chelonian host and protects the underlying epithelial cells.

Animal Diseases↗