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Biomedical subjects

F Haesebrouck

Publications and source records attributed to F Haesebrouck.

At least 127 records · Page 7Linked to original sources
PubMed1999

Colonization of rabbits with Staphylococcus aureus in flocks with and without chronic staphylococcosis.

Rabbits of 19 rabbitries were examined for the presence of Staphylococcus aureus in nine different body sites. Seven rabbitries experienced epidemically spreading signs of staphylococcosis while the other 12 rabbitries did not. S. aureus was isolated in all seven flocks that suffered from chronic problems of staphylococcosis and in 11 of the 12 clinically healthy flocks. The mean percentage of infected animals in these two groups was 90 and 43.3%, respectively. S. aureus was isolated from all body sites examined, but the ear and the perineum were often more intensely colonized. The number of animals colonized with S. aureus and the mean number of positive body sites in S. aureus positive rabbits were significantly higher in rabbitries with chronic staphylococcosis. This indicates that colonization capacity of S. aureus plays a role in epidemically spreading disease in rabbits. S. aureus isolates belonged to five different biotypes and 23 different phage types. Several different types simultaneously circulated in contaminated rabbitries and even simultaneously infected individual rabbits. Strains that belonged to the biotype-phage type combination mixed CV-C, 3A/3C/55/71 only occurred in rabbitries chronically dealing with signs of staphylococcosis. This may indicate a relationship between phenotypic strain properties and virulence of S. aureus.

Animals↗
PubMed1999

Oxidative activity of turkey monocytes, following the inoculation with Chlamydia psittaci.

Chemiluminescence (CL) was used to investigate the competence of turkey monocytes to mount a respiratory burst response upon interaction with Chlamydia psittaci. The oxidative activity of purified turkey monocytes, following inoculation with the avian C. psittaci serovar D strain 92/1293, was studied using luminol- and lucigenin-enhanced CL. Purified turkey monocytes were inoculated with C. psittaci at multiplicity of infection (MOI) of approximately 100, 10 and 1. In the presence of luminol, no detectable CL or only a weak CL response was obtained, and if present it increased with increasing MOI. Either sham inoculated monocytes, or monocyte-free control assays supplemented with C. psittaci, gave no detectable luminol-enhanced CL responses. In the lucigenin-enhanced assays, monocytes inoculated with C. psittaci demonstrated an immediate CL peak, the height of which was proportional to the MOI used. Following inoculations at a MOI 1, a faint second peak was observed, when applying high concentrations of lucigenin. Sham inoculated monocytes gave no detectable lucigenin-enhanced CL responses. However, in the presence of lucigenin, the addition of C psittaci to monocyte-free controls also resulted in an immediate CL peak, though no second peak was detected. This immediate lucigenin-dependent CL peak induced by C. psittaci was similar to the one observed in the presence of monocytes, and was not inhibited by superoxide dismutase. We demonstrated that this avian C. psittaci strain induces only a very weak respiratory burst response in turkey monocytes. In contrast, C. psittaci itself elicited an intense non-superoxide mediated lucigenin-dependent CL, indicating that in chlamydial research the detection of superoxide, using lucigenin, should be confirmed with a specific superoxide inhibitor.

Acridines↗
PubMed1999

Identification of aesculin-hydrolyzing streptococci, lactococci, aerococci and enterococci from subclinical intramammary infections in dairy cows.

Aesculin-hydrolyzing, catalase-negative, gram-positive cocci isolated from subclinical intramammary infections in dairy cows were identified to species level using growth characteristics and biochemical activity. The results indicated that the aesculin-hydrolyzing cocci associated with this type of infection are a very heterogenic group. S. uberis strains, including inulin- or beta-glucuronidase-negative isolates, accounted for only about one-third of the collection, and Enterococcus faecalis strains for one-fifth. Other species of some importance included (in descending order of isolation frequency) Aerococcus viridans, Streptococcus pluranimalium, Lactococcus garvieae, Streptococcus bovis and Streptococcus gallolyticus.

Animals↗
PubMed1999

Comparison of direct and enrichment methods for the selective isolation of vancomycin-resistant enterococci from feces of pigs and poultry.

Isolation results of vancomycin-resistant enterococci (VRE) of fecal samples from pigs and broiler and layer chickens obtained with two vancomycin-supplemented enrichment media, kanamycin aesculin azide (KAA) broth and Enterococcosel (ECC) broth, and three isolation media, KAA agar, ECC agar, and Slanetz and Bartley (SL) agar, were compared. Direct isolation on vancomycin-containing agar plates was not efficient in swine and layer chickens, which had only low numbers of VRE. In broilers chickens, the VRE content of the samples was high, and SL as well as ECC were found to perform better than KAA agar. The same three agar media were used as selective plating media after 1 and 2 days incubation of the samples in KAA and ECC enrichment broths. Sensitivities of the 12 different enrichment-plate combinations tested ranged from 0 to 81% in layer chickens and from 5 to 44% in samples from pigs. In the high prevalence type of samples from broilers, sensitivities still varied substantially from 52 to 78%. Incubating vancomycin-containing enrichment broths for 2 days compared with 1 day was favorable for the isolation of vancomycin-resistant Enterococcus faecalis, E. gallinarum, and E. casseliflavus but not for E. faecium and E. hirae/E. durans. ECC broth and ECC plates yielded the highest number of E. gallinarum and E. casseliflavus. In layer as well as in broiler chickens, ECC broth incubated for 2 days and plated on ECC agar was the most sensitive method. In pigs, however, KAA broth incubated for 2 days and plated on ECC medium yielded the highest number of VRE.

Animals↗
PubMed1999

Streptococcus intestinalis Robinson et al. 1988 and Streptococcus alactolyticus Farrow et al. 1984 are phenotypically indistinguishable.

The one-dimensional whole-cell protein patterns and a variety of biochemical characteristics of the type and reference strains of Streptococcus intestinalis and Streptococcus alactolyticus were studied. All the data revealed that strains of both species were indistinguishable. Reported differences in haemolytic activity and presence of Lancefield antigens were not reproduced. All strains were alpha-haemolytic. The S. intestinalis type strain possessed the group G antigen, but a second S. intestinalis reference strain and all of the S. alactolyticus strains possessed the group D antigen. All strains produced urease activity (albeit some after prolonged incubation), a characteristic considered important for S. intestinalis. Given the congruence between whole-cell protein electrophoresis and percentage of DNA-DNA hybridization, these data suggest that Streptococcus intestinalis Robinson et al. 1988 is a junior synonym of Streptococcus alactolyticus Farrow et al. 1984.

Animals↗
PubMed1999

Streptococcus pluranimalium sp. nov., from cattle and other animals.

Strains from subclinical mastitis, from the genital tract and tonsils of cattle, from tonsils of a goat and a cat and from the crop and the respiratory tract of canaries were found to constitute a new streptococcal species, for which the name Streptococcus pluranimalium sp. nov. is proposed. Sequencing of 16S rRNA showed that Streptococcus thoraltensis and Streptococcus hyovaginalis were its closest known phylogenetic relatives. The new species showed some phenotypic resemblance to the poorly described species Streptococcus acidominimus, but whole-cell protein analysis and 16S rRNA sequencing revealed that the new species was only distantly related to the type strain of S. acidominimus. Identification of these bacteria, which showed heterogeneous biochemical reaction patterns, was most reliably made by whole-cell protein analysis. Nevertheless, a number of biochemical reactions can be used to differentiate S. pluranimalium from other animal streptococci. Strain LMG 14177T, isolated from mastitic milk of a dairy cow, was designated as the type strain of S. pluranimalium sp. nov.

Animals↗
PubMed1999

Phylogenetic characterization of 'Candidatus Helicobacter bovis', a new gastric helicobacter in cattle.

Recently helicobacter-like organisms have been reported in the pyloric part of the abomasum of calves and adult cattle. Cultivation of these spiral bacteria has not been successful to date. In the present study, comparative 16S rDNA sequence analysis was used to determine the taxonomic position of these bacteria. Seven abomasal biopsies of adult cattle were sampled from different Belgian and Dutch farms. In all samples the presence of helicobacter-like organisms was demonstrated by biochemical, immunohistochemical and electron microscopical data. Bacterial 16S rDNA was amplified by PCR and sequences were determined either by direct or indirect sequence analysis. Pairwise comparisons revealed all sequences to be more than 99% homologous. Phylogenetic analysis placed the organism, corresponding to the reference sequence R2XA, within the genus Helicobacter. A diagnostic PCR assay was designed, differentiating all of the bovine 16S rDNA sequences from Helicobacter and Wolinella species. The low similarity level towards Helicobacter bilis (92.8%), its closest validly named neighbour, indicates that this novel taxon is indeed a novel Helicobacter species. An in situ hybridization procedure associated the bovine sequences to the helicobacter-like organisms in the abomasum. The name 'Candidatus Helicobacter bovis' is proposed for this new abomasal helicobacter from cattle.

Abomasum↗
PubMed1999

'Candidatus Helicobacter suis', a gastric helicobacter from pigs, and its phylogenetic relatedness to other gastrospirilla.

'Gastrospirillum suis' is an uncultured, tightly spiral micro-organism that has been associated with ulcer disease in the stomachs of pigs. It was the purpose of this study to determine the phylogenetic position of 'G. suis'. Stomachs of five slaughterhouse pigs, originating from different Belgian and Dutch farms, were selected on the basis of the presence of 'G. suis'-like bacteria, as demonstrated by biochemical, immunohistochemical and electron microscopical data. Bacterial 16S rDNA was amplified by PCR using broad-range primers and five helicobacter-like sequences were determined either by direct or indirect sequence analysis. An inter-sequence homology of 99.7% was observed, suggesting that the sequences originated from strains belonging to a single species. Phylogenetic analysis of the consensus sequence placed the organism within the genus Helicobacter, where it formed a distinct sub-group together with other gastrospirillum-like bacteria (Helicobacter felis, Helicobacter bizzozeronii, Helicobacter salomonis and 'Helicobacter heilmannii' types 1 and 2). Diagnostic PCR primers and a probe were developed that differentiated the porcine sequences from all known helicobacters. These results indicate that the porcine sequences represent a single taxon within the genus Helicobacter. The low similarity level towards H. salomonis (96.6%), its closest validly named neighbour, strongly suggests that this taxon is a novel Helicobacter species. In situ hybridization experiments linked the reference sequence to the 'G. suis'-like bacteria. On the basis of these results, we propose the name 'Candidatus Helicobacter suis' for this gastric helicobacter from pigs.

Animals↗
PubMed1999

Phenotypic distinction in Enterococcus faecium and Enterococcus faecalis strains between susceptibility and resistance to growth-enhancing antibiotics.

Susceptibility of Enterococcus faecium and Enterococcus faecalis strains from animals and foods to growth-promoting antibiotics used in animal feed was tested by the agar dilution technique. Acquired resistance to bacitracin, narasin, tylosin, and virginiamycin was seen for both species, and for E. faecium, resistance to avilamycin and avoparcin was also seen. Drawing the distinction between susceptibility and resistance based on frequency distributions of MICs was easy with avoparcin, avilamycin, and tylosin but difficult with virginiamycin and to some extent also with bacitracin and narasin.

Animals↗
PubMed1999

Significance of host cell kinesin in the development of Chlamydia psittaci.

The influence of the microtubule-associated motor protein kinesin on Chlamydia psittaci inclusion development in epithelial and fibroblast cell lines was addressed. Kinesin was blocked early after chlamydial internalization (4 h postinfection [p.i.]) and before the initiation of active chlamydial multiplication (8 h p.i.). Chlamydia development was monitored by fluorescence and transmission electron microscopy at different times during the cycle. In both host cell lines, kinesin blockage restricted mitochondria from the chlamydial vacuole. The effects of kinesin blockage on the C. psittaci replication cycle included the presence of multiple inclusions up to late in the cycle, the presence of enlarged pleomorphic reticulate bodies, and a delayed reappearance of elementary bodies. The last effect seems to be greater when kinesin is blocked early after infection. Our results show that kinesin activity is required for optimal development of these microorganisms, most probably acting through the apposition of mitochondria to the C. psittaci inclusions.

Adenosine Triphosphate↗
PubMed1999

Identification of nonlipophilic corynebacteria isolated from dairy cows with mastitis.

Nonlipophilic corynebacteria associated with clinical and subclinical mastitis in dairy cows were found to belong to four species: Corynebacterium amycolatum, Corynebacterium ulcerans, Corynebacterium pseudotuberculosis, and Corynebacterium minutissimum. These species may easily be confused. However, clear-cut differences between C. ulcerans and C. pseudotuberculosis were found in their acid production from maltotriose and ethylene glycol, susceptibility to vibriostatic agent O129, and alkaline phosphatase. Absence of growth at 20 degrees C and lack of alpha-glucosidase and 4MU-alpha-D-glycoside hydrolysis activity differentiated C. amycolatum from C. pseudotuberculosis and C. ulcerans. The mastitis C. pseudotuberculosis strains differed from the biovar equi and ovis reference strains and from caprine field strains in their colony morphologies and in their reduced inhibitory activity on staphylococcal beta-hemolysin. C. amycolatum was the most frequently isolated nonlipophilic corynebacterium.

Acids↗
PubMed1998

Rhizomucor pusillus mucormycosis combined with chlamydiosis in an African grey parrot (Psittacus erithacus erithacus).

This paper describes a case of mucormycosis combined with chlamydiosis in an African grey parrot (Psittacus erithacus erithacus). The clinical signs included diarrhoea, an unsteady gait and a twisted neck. Smears of the spleen, liver and contents of the cloaca stained strongly positive for Chlamydia species. Histologically, hyphae typical of Zygomycetes were observed invading through the walls of blood vessels of the spleen. Rhizomucor pusillus was isolated as a pure culture from the intestines, lungs and liver.

Animals↗
PubMed1998

Verrucous endocarditis due to Escherichia coli in a Persian cat.

Verrucous endocarditis of the aortic valves was diagnosed postmortem in a Persian cat that died after showing clinical signs of dyspnoea, hypothermia and anorexia. Bacterial colonies were evident on Giemsa-stained sections of the valves and Escherichia coli was isolated from the endocarditis lesions.

Animals↗
PubMed1998

Role of the humoral immune system in Salmonella enteritidis phage type four infection in chickens.

The role of avian humoral immunity in the clearance of S. enteritidis was evaluated through bursectomy. After oral inoculation of bursectomized and sham-treated chickens with S. enteritidis, faecal excretion of S. enteritidis was examined. Organs were collected weekly until six weeks post-inoculation (pi) for bacteriological enumeration. Antibody isotypes in serum and bile were quantified by ELISA. Faecal excretion of S. enteritidis was significantly lower in controls from 13 days pi. Numbers of S. enteritidis in caeca from controls were significantly decreased from three weeks pi. Numbers of S. enteritidis were significantly decreased at two weeks pi in the spleen and the liver and at six weeks pi in the liver. Antibodies to S. enteritidis peaked at two weeks pi in controls and were absent in bursectomized chickens. These findings indicate that elimination of S. enteritidis partly depends on humoral immunity. The intestinal humoral response appeared more effective than the systemic humoral response for elimination of S. enteritidis.

Animals↗
PubMed1998

Characterization of four Flavobacterium columnare (Flexibacter columnaris) strains isolated from tropical fish.

Four Flavobacterium columnare strains (AJS 1-4) were isolated from black mollies (Poecilia sphenops) and platies (Xiphophorus maculatus), showing white spots on the back, head and skin ulcers. The isolates developed characteristic rhizoid yellow pigmented colonies on Shieh agar and typical growth in Shieh broth. They were Gram-negative, filamentous bacteria exhibiting flexing movements. When compared to F. columnare strains isolated from temperate fish, it was noted that the four strains originating from tropical aquarium fish are more capable of growing at higher temperatures, the opposite being true for the strains isolated from temperate fish. Biochemical characterization and agglutination tests proved that the isolated strains could be classified as F. columnare. Low minimal inhibitory concentration (MIC) values were found for chloramphenicol, erythromycin, furazolidone, kanamycin, lincomycin, nalidixic acid, oxytetracycline and streptomycin. MIC values were high for colistin, sulfamethoxazole and neomycin. Pathogenicity studies were performed on black mollies. When these animals were submersed in an infective solution of the F. columnare strains, a marked difference in virulence was noted among the four isolated strains, strain AJS 1 being the most virulent one and strain AJS 4 being of low virulence.

Agglutination Tests↗
PubMed1998

Serological and bacteriological observations on experimental infection with Salmonella hadar in chickens.

Over the past 3 years the frequency of Salmonella hadar infections has increased in Belgium in both poultry and humans. Therefore, the course of infection with S. hadar in poultry was investigated. One day-old and 4 week-old specific pathogen-free chickens were orally infected with one of two S. hadar strains, SH1 or SH2. Mortality was 6% (SH1) and 17% (SH2) in birds infected at 1 day-old. Chickens infected at 1 day-old with SH2 showed a mild diarrhoea. The S. hadar faecal excretion in birds infected at 1 day-old remained high throughout the experiment until 12 weeks post-inoculation (pi). Faecal excretion was lower in older birds. Antibodies to S. hadar were observed from 2 weeks pi (SH2, infected at 1 day-old) or 4 weeks pi (SH1, both groups; SH2, chickens infected at 4 weeks of age). The percentage of chickens with antibodies was higher after infection at 1 day-old than after infection at 4 weeks of age. In a second experiment 1 day-old chicks were infected with SH1 and autopsied at regular intervals until 42 days pi. SH1 was isolated from the caeca from 3 h pi onwards and from the liver and spleen from 18 h until 14 days pi. Serous typhlitis and omphalitis were the main lesions. The number of macrophages in the lamina propria of the caecal tonsils was slightly increased from 18 h until 2 weeks pi. In the liver, inflammation was observed in the portal triads and in the sinusoids. This study indicates that infections with S. hadar lead to intense colonisation of the gut and extensive faecal shedding. It may also cause invasive infections in 1 day-old chickens.

Age Factors↗