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Biomedical subjects

F Haesebrouck

Publications and source records attributed to F Haesebrouck.

At least 37 records · Page 2Linked to original sources
PubMed2004

In vitro growth inhibition of major mastitis pathogens by Staphylococcus chromogenes originating from teat apices of dairy heifers.

Earlier field observations suggest that teat apex colonization by Staphylococcus chromogenes pre-partum in dairy heifers protects udder quarters against elevated somatic cell counts early post-partum. To explain these findings, the in vitro inhibitory capability of S. chromogenes from teat apices of heifers towards some major mastitis pathogens was tested using a modified cross-streaking method. Two out of 10 S. chromogenes isolates, both originating from two different teats from the same heifer, consistently inhibited growth of all Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus uberis strains, but none of the Escherichia coli strains. The present study, therefore, supports the protective effect of teat apex colonization by S. chromogenes by in vitro production of inhibitory substances.

Animals↗
PubMed2004

Piscine mycobacteriosis: a literature review covering the agent and the disease it causes in fish and humans.

Mycobacterium marinum, M. fortuitum and M. chelonae are the etiological agents of fish mycobacteriosis. Fish mycobacteriosis is a disseminated infection reported in more than 150 fish species and is usually accompanied by emaciation and death over a period of months to years. Granulomas are formed both externally and scattered throughout the internal organs. Treatment is in most cases unsatisfactory and the overall recommendation is to destroy the diseased stock, particularly since these pathogens are capable of affecting man as well as fish. Especially fish handlers and aquarium hobbyists are infected and the disease is mostly confined to the superficial, cooler body tissues, most often the extremities. Dissemination is apparently rare but has been reported.

Animals↗
PubMed2004

Fatal meningitis in a calf caused by Mannheimia varigena.

Mannheimia varigena was identified as the etiologic agent of meningitis in a young Belgian White Blue heifer calf. Species identification of the bacterium was done by phenotyping and molecularly confirmed by tDNA-PCR. Standard bacteriological examination might fail to differentiate species belonging to the genus Mannheimia.

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

Susceptibility of Clostridium perfringens strains from broiler chickens to antibiotics and anticoccidials.

Clostridium perfringens strains isolated in 2002 from the intestines of broiler chickens from 31 different farms located in Belgium were tested for susceptibility to 12 antibiotics used for therapy, growth promotion or prevention of coccidiosis. All strains were uniformly sensitive to the ionophore antibiotics monensin, lasalocid, salinomycin, maduramycin and narasin. All were sensitive to avilamycin, tylosin and amoxicillin, while flavomycin (bambermycin) showed low or no activity. Chlortetracycline and oxytetracycline were active at very low concentrations, but low-level acquired resistance was detected in 66% of the strains investigated. Fifty percent of these strains carried the tetP(B) resistance gene, while the tet(Q) gene was detected in only one strain. One strain with high-level resistance against tetracyclines carried the tet(M) gene. Sixty-three percent of the strains showed low-level resistance to lincomycin. The lnu(A) and lnu(B) genes were each only found in one strain. Compared with a similar investigation carried out in 1980, an increase was seen in resistance percentages with lincomycin (63% against 49%) and a slight decrease with tetracycline (66% against 74%).

Animals↗
PubMed2004

Antibiotic resistance among fecal indicator bacteria from healthy individually owned and kennel dogs.

Escherichia coli and Enterococcus faecalis strains isolated from anal swabs of clinically healthy dogs were examined for the presence of acquired antimicrobial resistance. The strains originated from dogs of 92 different owners and from eight breeding kennels. The purpose of the present study was to evaluate the resistance situation in the intestinal flora of the dog to assess the possible role of the dog flora as a reservoir of antimicrobial resistance. Multiple resistance was rarely found in E. coli strains collected from individually owned dogs, in contrast with strains from kennel dogs. Resistance to ampicillin, trimethoprim, and sulfamethoxazole was significantly less prevalent in E. coli from privately owned dogs than in strains from kennel dogs. Resistance rates against tetracycline and macrolides were unexpectedly high in E. faecalis strains. Two and three E. faecalis strains from individually owned dogs and kennel dogs, respectively, were resistant to gentamicin, an antibiotic often used for treating enterococcal infections in humans. This study demonstrates that resistance percentages may fluctuate with the choice of dog population. The observed antimicrobial resistance percentages indicate that the flora of healthy dogs may act as a reservoir of resistance genes.

Animals↗
PubMed2004

Distribution of the erm (B) gene, tetracycline resistance genes, and Tn1545-like transposons in macrolide- and lincosamide-resistant enterococci from pigs and humans.

The distribution of the erm (B) and the tetracycline resistance genes tet(K), tet(L), tet(M), tet(O), and tet(S) was investigated among macrolide- and lincosamide-resistant enterococci originating from humans, pigs, and pork carcasses. The presence of transposons of the Tn916/Tn1545 family was also traced in these isolates. Furthermore, the porcine strains were tested for the presence of glycopeptide resistance genes vanA and vanB. The erm(B) gene was found in 85% of the porcine and in all human isolates. Ninety-eight percent of the porcine and 89% of the human erm(B)-positive enterococci carried the tet(M) gene. Seventy-seven percent and 70%, respectively, of these strains harbored a Tn1545-like element. Tet(L) was observed in 68% of the porcine and in 65% of the human enterococci. The other tetracycline resistance genes were very rare and the glycopeptide resistance genes vanA and vanB were not detected among the porcine isolates. The similar frequencies of resistance genes and the highly mobile Tn1545-like transposon among porcine and human enterococci might indicate exchange of resistant strains or their resistance genes between humans and pigs or the existence of a common reservoir.

Animals↗
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

Streptococcus minor sp. nov., from faecal samples and tonsils of domestic animals.

Nine isolates, which were obtained from tonsils, anal swabs and faeces of dogs and from tonsils of a cat and a calf, constituted a homogeneous but unidentified taxon after screening with tRNA intergenic length polymorphism analysis and whole-cell protein fingerprinting. 16S rDNA sequence analysis classified representative strains in the genus Streptococcus. Highest sequence similarity (95.9 %) was obtained with Streptococcus ovis. Growth characteristics, biochemical features, DNA-DNA hybridization and DNA G+C contents of selected strains demonstrated that they represent a single, novel streptococcal species. The name Streptococcus minor sp. nov. is proposed for the novel species; the type strain (ON59(T)=LMG 21734(T)=CCUG 47487(T)) was isolated from a dog tonsil.

Animals↗
PubMed2004

Enterococcus saccharominimus sp. nov., from dairy products.

Four isolates, which were obtained from Belgian, Moroccan and Romanian dairy products, constituted a homogeneous but unidentified taxon after screening with whole-cell protein fingerprinting. Complete 16S rRNA gene sequence analysis classified representative strains in the genus Enterococcus. Highest sequence similarities of 98.6 and 98.0 % were obtained with the species Enterococcus sulfureus and Enterococcus saccharolyticus, respectively. Growth characteristics, biochemical features, tRNA intergenic length polymorphism analysis, DNA-DNA hybridization and DNA G+C contents of selected strains demonstrated that they represent a single, novel Enterococcus species. It differs phenotypically from other enterococci in characteristics commonly considered as typical of this genus: no growth in 6.5 % NaCl or 0.4 % sodium azide, and no acid production from a wide range of carbohydrates. The name Enterococcus saccharominimus sp. nov. is proposed for this novel species; the type strain (LMG 21727(T)=CCM 7220(T)) was isolated from contaminated pasteurized cow's milk.

Anti-Bacterial Agents↗
PubMed2004

In vitro susceptibilities of Mycoplasma hyopneumoniae field isolates.

The in vitro susceptibilities of 21 Mycoplasma hyopneumoniae field isolates were determined using a broth microdilution technique. One isolate showed acquired resistance to lincomycin, tilmicosin, and tylosin, while five isolates were resistant to flumequine and enrofloxacin. Acquired resistance against these antimicrobials in M. hyopneumoniae field isolates was not reported previously.

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↗
PubMed2004

Multiplex PCR assay for differentiation of Helicobacter felis, H. bizzozeronii, and H. salomonis.

Helicobacter felis, Helicobacter bizzozeronii, and Helicobacter salomonis are frequently found in the gastric mucous membrane of dogs and cats. These large spiral organisms are phylogenetically highly related to each other. Their fastidious nature makes it difficult to cultivate them in vitro, hampering traditional identification methods. We describe here a multiplex PCR test based on the tRNA intergenic spacers and on the urease gene, combined with capillary electrophoresis, that allows discrimination of these three species. In combination with previously described 16S ribosomal DNA-based primers specific for the nonculturable "Candidatus Helicobacter suis," our procedure was shown to be very useful in determining the species identity of "Helicobacter heilmannii"-like organisms observed in human stomachs and will facilitate research concerning their possible zoonotic importance.

Animals↗
PubMed2003

Evaluation of virulence of Mycoplasma hyopneumoniae field isolates.

The course of enzootic pneumonia, caused by Mycoplasma hyopneumoniae, is strongly influenced by management and housing conditions. Other factors, including differences in virulence between M. hyopneumoniae strains, may also be involved. The aim of this study was to evaluate the virulence of six M. hyopneumoniae field isolates and link it to genetic differences as determined by randomly amplified polymorphic DNA (RAPD) analysis. Ninety, conventional M. hyopneumoniae-free piglets were inoculated intratracheally with the field isolates, a virulent reference strain or sterile culture medium. Animals were examined daily for the presence of disease signs and a respiratory disease score (RDS) was assessed per pig. Twenty-eight days post infection, pigs were euthanized, blood sampled and a lung lesion score was given. Lung samples were processed for histopathology, immunofluorescence testing for M. hyopneumoniae and isolation of M. hyopneumoniae. RAPD analysis was performed on all M. hyopneumoniae strains. Significant differences between isolates were found for the RDS, lung lesion score, histopathology, immunofluorescence and serology. Based on the results of the different parameters, isolates were divided into three "virulence" groups: low, moderately and highly virulent strains. Typically, a 5000 bp RAPD fragment was associated with the highly and moderately virulent strains whereas it was absent in low virulent strains. It was concluded that high variation in virulence exists between M. hyopneumoniae strains isolated from different swine herds. Further studies are required to determine whether the 5000 bp fragment obtained in the RAPD analysis can be used as a virulence marker.

Animals↗