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F Pasmans

Publications and source records attributed to F Pasmans.

At least 19 recordsLinked to original sources
PubMed2005

Virulence-associated traits in avian Escherichia coli: comparison between isolates from colibacillosis-affected and clinically healthy layer flocks.

Colibacillosis appears to be of increasing importance in layer flocks. The aim of this study was to determine characteristics of avian pathogenic Escherichia coli associated with the occurrence of colibacillosis outbreaks at flock level. Forty E. coli strains originating from layers from healthy flocks ('control isolates'), consisting of 25 caecal and 15 extra-intestinal isolates, were compared with 40 strains isolated from layers originating from colibacillosis-affected flocks ('outbreak isolates'), consisting of 20 caecal and 20 extra-intestinal isolates. The examined characteristics were adhesins, invasivity in T84 cell culture, serum resistance, iron uptake, colicin production, and toxinogenicity. The following traits were significantly more often detected in the outbreak isolates than in the control isolates: tsh, iss, iucA, iutA, irp2, fyuA, iroC, cvaC, colicin and colicin V production. A comparison of the extra-intestinal outbreak isolates and the caecal control isolates yielded the same results as when the caecal isolates, extra-intestinal isolates and total number of isolates of the outbreak and the control group were compared. When comparing the caecal and extra-intestinal isolates within the control and within the outbreak group, no significant differences were detected. The O78 and O2 groups showed significant differences with other O-types and NT strains for prevalence of most of the same characteristics. The combination of type 1 fimbriae, tsh, serum resistance, iss, traT, iucA, fyuA, iroC and colicin or colicin V production was significantly more often present in extra-intestinal outbreak isolates than in extra-intestinal control isolates. Only the combination of serum resistance, fyuA and colicin production was present in all outbreak isolates, with a significantly lower prevalence in the control isolates. None of the characteristics or combinations examined were exclusive to the outbreak isolates.

Adhesins, Escherichia coli↗
PubMed2005

Survival of Salmonella serovar Typhimurium inside porcine monocytes is associated with complement binding and suppression of the production of reactive oxygen species.

The development of the carrier state in swine after infection with Salmonella serovar Typhimurium (S. Typhimurium) has not been elucidated yet. Possibly, phagocytes like macrophages play a crucial role. It was the aim of the present study to characterize the interaction of a S. Typhimurium strain and its hilA and ssrA mutants with porcine peripheral blood monocytes (PBM). Exposure of porcine PBM to S. Typhimurium induced the production of reactive oxygen species (ROS), requiring bacterial protein synthesis. The numbers of intracellular bacteria sharply decreased over a period of 3h. Monocytes obtained from different pigs differed markedly in their ROS production and in their ability to kill the bacteria. Interestingly, high ROS production did not coincide with increased intracellular killing. Using diphenylene iodonium inhibition of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, it was shown that bacterial killing was ROS-dependent only within 1h post inoculation, but was ROS-independent from 1h post inoculation onwards. This might be explained by the finding that metabolically active Salmonella bacteria were capable of suppressing the respiratory burst activity in a SPI-1- and SPI-2-independent manner without causing measurable cell damage. Opsonization with complement did not alter the ROS production. Nevertheless, it increased intracellular survival of the bacteria. In conclusion, survival of S. Typhimurium inside porcine PBM is promoted by suppression of respiratory burst activity and complement binding.

Animals↗
PubMed2004

Bacteria-host interactions of Salmonella Paratyphi B dT+ in poultry.

In recent years, a dramatic increase in incidence of the dextro-rotatory tartrate-positive variant (dT+) of Salmonella enterica subspecies enterica serovar Paratyphi B has been observed in poultry and poultry products. In the present study the interactions of this bacterium with the host were studied in vivo and in vitro in an attempt to explain the preferential association of this serotype with poultry. The ability of this organism to invade and multiply in chicken intestinal epithelial cells and the intracellular behaviour in chicken macrophages was studied in vitro using chicken cell lines. In vivo challenge experiments in specific pathogen-free chickens were carried out to determine the level of colonization of caeca and internal organs early after experimental infection. An in vivo trial with commercial broiler chickens, using a seeder model, was performed to determine whether S. Paratyphi B dT+ could persist and spread in broilers until slaughter. S. Paratyphi B dT+ invaded and multiplied in the chicken epithelial cell line and survived in a chicken macrophage cell line. The strain used colonized caeca and internal organs of chickens to a high extent 1 week after infection with a low-dose inoculum. Moreover, the strain was efficiently transmitted within a group of broilers and persisted until slaughter. It was concluded that S. Paratyphi B dT+ was well adapted to poultry and therefore it is suggested that specific control measures against this serotype should be considered.

Animals↗
PubMed2004

Colibacillosis in caged layer hens: characteristics of the disease and the aetiological agent.

In Europe, outbreaks of acute mortality in layer flocks due to colisepticaemia have frequently been observed since the mid-1990s. The aims of this study were to describe the disease, to identify the serotypes of the avian pathogenic Escherichia coli (APEC) present in these outbreaks, and to detect the presence of F11 fimbriae and flagella in the isolates. For this purpose, 20 flocks with APEC-associated increased mortality and 20 control flocks matched for age were examined. Weekly mortality rates in the colibacillosis-affected flocks reached 1.71%, versus 0.30% in the control flocks. The maximum cumulative mortality over an entire colibacillosis outbreak reached 9.19%. The disease was often flock and hen house associated, with recurrent outbreaks within one round and in successive rounds in the same house. Disease was usually acute without clinical symptoms. Peritonitis with yolk material deposited in the peritoneal cavity and polyserositis were the main lesions at necropsy. O78 strains were isolated in 15 of the 20 colibacillosis flocks, and in only one of the control flocks. The majority of strains from the control flocks could not be serotyped by the 28 O-antisera used. In general, F11 fimbriae and flagella were present in the majority of the strains. F11 fimbriae were significantly more often found in O78 isolates than in the other serotypes, and are thus more often present in isolates from colibacillosis flocks. Strains positive for F11, and for F11 and flagella, were more frequently present in heart and liver of the colibacillosis-affected flocks.

Animals↗
PubMed2004

Significance of interactions between Escherichia coli and respiratory pathogens in layer hen flocks suffering from colibacillosis-associated mortality.

This study aimed to examine the significance of interactions between Escherichia coli and various respiratory pathogens during outbreaks of colibacillosis-associated mortality in layer hen flocks under field conditions. For this purpose, a case-control study involving 20 control flocks with baseline mortality and 20 flocks with increased mortality due to E. coli septicaemia and polyserositis, was conducted. In each colibacillosis flock, blood samples were taken from 20 hens at the onset of clinical disease and three times thereafter at 2-week intervals. Control flocks of comparable ages were sampled in the same way. Pooled sera, taken at the first and last sampling, were examined for antibody titres against infectious bronchitis virus (IBV) and Newcastle disease virus (NDV), and the individual sera from all four samplings were examined for the presence and/or titres of antibodies against avian pneumovirus (APV), Mycoplasma gallisepticum, Mycoplasma synoviae and Ornithobacterium rhinotracheale. Titre increases were seen for IBV D274 (one control flock) and O. rhinotracheale (one control and one colibacillosis flock). An increase in per cent reactors was seen for APV (one control flock), and for M. synoviae (one control and two colibacillosis flocks). The study failed to detect any consistent interactions between E. coli and the aforementioned pathogens. These results indicate that, at least as observed in this study, outbreaks of increased mortality resulting from colibacillosis are not necessarily associated with IBV, NDV, APV, M. gallisepticum, M. synoviae or O. rhinotracheale infections.

Animals↗
PubMed2004

Risk factors associated with colibacillosis outbreaks in caged layer flocks.

Colibacillosis appears to be of increasing significance in layer flocks, but there have been no studies of the risk factors associated with outbreaks. This study aimed to investigate the possible associations between risk factors of non-infectious nature and outbreaks of mortality due to colibacillosis in flocks of caged layer hens. Information on management, biosecurity measures and housing conditions was collected in 20 flocks suffering from the disease and in 20 clinically healthy control flocks. The data were processed using multiple logistic regression. The statistical analysis demonstrated that an increase in the distance to the nearest poultry farm by 1 km was associated with a six-fold decreased risk of an outbreak of colibacillosis (odds ratio=0.16). Furthermore, a 1 l increase in cage volume per hen was associated with a 33% decrease in the risk of an outbreak (odds ratio=0.75). It was concluded that the distance between poultry farms and the hen density in the cages are important risk factors for outbreaks of colibacillosis in flocks of layer hens.

Animal Husbandry↗
PubMed2004

Microencapsulated short-chain fatty acids in feed modify colonization and invasion early after infection with Salmonella enteritidis in young chickens.

Short-chain fatty acids (SCFA) are widely used as feed additives in poultry for the control of pathogenic bacteria, such as Salmonella enteritidis. Recently, a new range of products was developed in which SCFA are encapsulated in mineral carriers, resulting in a slow release during the transport of these carriers through the intestinal tract. To test the efficacy of this type of products against early colonization after Salmonella infection in poultry, a challenge experiment with S. enteritidis was performed. Five groups of 20 chickens were given feed with no supplement or feed supplemented with acetic acid (0.24%), formic acid (0.22%), or propionic acid (0.27%) as film-coated microbeads or butyric acid (0.15%) as spray-cooled microcapsules. The 5 groups were challenged with 5 x 10(3) cfu S. enteritidis at d 5 and 6 posthatch, and samples of ceca, liver, and spleen were taken at d 8 and analyzed for the number of colony-forming units of Salmonella per gram of tissue. Feed supplementation with acetic acid, and to a lesser extent formic acid, resulted in an increase of colonization of ceca and internal organs. Birds receiving propionic acid-coated microbeads as feed supplement were colonized with Salmonella to the same extent as controls. Butyric acid-impregnated microbeads in the feed, however, resulted in a significant decrease of colonization by S. enteritidis in the ceca but not in liver and spleen.

Animal Feed↗
PubMed2004

Intermittent long-term shedding and induction of carrier birds after infection of chickens early posthatch with a low or high dose of Salmonella enteritidis.

Poultry are very likely to become infected with Salmonella in the early posthatch period, due to environmental contamination. The purpose of this study was to evaluate the effect of infection dose on the risk of persistent infection in laying hens. In this study, young layer chicks were orally infected with a low (10(2) at 1 d posthatch) or a high dose (10(9) cfu at 1 wk posthatch) of Salmonella Enteritidis. The pattern and duration of fecal shedding was studied for 18 wk. All chickens shed Salmonella early after infection and shed Salmonella intermittently during the whole study period. There were more positive birds in the high-dose group than in the low-dose group in the first weeks following Salmonella exposure. From 10 wk postinfection onwards, however, birds that were orally infected with the low dose of Salmonella Enteritidis shed more Salmonella than the birds that received the high dose. At 18 wk of age, there was no difference in cecal colonization between the treatment groups. It can be concluded that infection of newly hatched chicks with a low dose of Salmonella Enteritidis can lead to persistent infection until onset of lay, hereby excreting Salmonella bacteria intermittently.

Animals↗
PubMed2004

Tubular glands of the isthmus are the predominant colonization site of Salmonella enteritidis in the upper oviduct of laying hens.

Salmonella enterica serovar Enteritidis is the serovar most frequently isolated from chicken eggs. Colonization of the upper oviduct of hens is believed to play an important role in egg contamination. The interaction of S. enteritidis with gland epithelial cells of the isthmus and the magnum was, therefore, studied in vitro and in vivo. In the first experiment, S. enteritidis bacteria were added to confluent monolayers of primary cultures of chicken tubular epithelial cells of the isthmus (ICTEC) or magnum (MCTEC). Intracellular bacteria in ICTEC and MCTEC were confirmed by a gentamicin protection assay. Internalization in the glandular cells was corroborated by confocal scanning microscopy. Although S. enteritidis was able to invade and proliferate intracellularly during 24 h in the cell culture of both segments, this was significantly more so in the ICTEC. In a second experiment, an in vivo loop model was developed for investigation of the invasiveness of S. enteritidis in the oviduct of laying hens. Loops in the isthmus and magnum of laying hens were made under anaesthesia. S. enteritidis was inoculated into each loop. After 1 h, tubular gland cells were isolated from the infected tissue under gentamicin. S. enteritidis invasiveness was measured as the ratio of isolated bacteria per isolated tubular gland cell. This ratio was higher (P < 0.01) in the isthmus (1.3 x 10(-3)) than in the magnum (5.3 x 10(-5)). In a third experiment, laying hens were intravenously infected with 5 x 10(7) cfu S. enteritidis bacteria. The number of intracellular bacteria was counted in the tubular gland cells of the isthmus and magnum after isolation under gentamicin. The ratio of isolated bacteria per isolated tubular gland cell was again significantly higher in the isthmus as compared with in the magnum. In all 3 assays, the tubular gland cells of the isthmus were more heavily invaded than those of the magnum.

Animals↗
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↗