Prevalence of dermatophytes in asymptomatic guinea pigs and rabbits.
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Animals↗
Biomedical subjects
F Haesebrouck
Publications and source records attributed to F Haesebrouck.
In vitro susceptibility of Enterococcus faecium isolated from food to growth-promoting and therapeutic antibiotics.
A total of 76 E. faecium strains, isolated at retail level from raw poultry meat, cheese, raw pork, and preparations of cheese and raw pork, were tested for their susceptibility and resistance to growth-promoting antibacterials used in animals and antibiotics used therapeutically in humans. All strains were uniformly susceptible to the growth promoters bambermycin and avilamycin. Resistance against bacitracin, virginiamycin and narasin was high among strains from poultry meat. With tylosin, a macrolide antibiotic used therapeutically and for growth promotion, resistance was mainly detected in strains originating from poultry meat, though also in some strains from pork and from pork and cheese preparations. The therapeutic antibiotic dalfopristin/quinupristin did not show full cross-resistance with the growth-promoting antibiotic virginiamycin. With dalfopristin/quinupristin two different levels of resistance were found. Only one E. faecium strain isolated from poultry was resistant to the glycopeptides avoparcin and vancomycin. Only one poultry meat strain was highly resistant to ampicillin. However, nearly all poultry meat strains showed decreased sensitivity. Only 3 out of 24 poultry strains were susceptible to minocycline, while all strains from other origins were susceptible to this tetracycline antibiotic. High-level streptomycin resistance was seen in strains of all origins, though infrequently. High-level gentamicin resistance was not found.
Animal Husbandry↗
Colonisation of rabbits with Staphylococcus aureus after experimental infection with high and low virulence strains.
Four groups of 12 rabbits each were inoculated in the nose with strains with suspected differences in virulence. In the two groups infected with strains from severe outbreaks, belonging to a rabbit-pathogenic biotype-phage type combination, 6-12 rabbits were found positive at the successive bacteriological samplings over a period of 28 days. In the two other groups, infected with strains obtained from rabbitries without a history of staphylococcosis, the number of Staphylococcus aureus positive animals quickly became negative but increased again after 1 week to 1-5 positive animals until the end of the experiment. Two rabbits in each group inoculated with a high virulence strain developed purulent skin lesions, while in the groups inoculated with low virulence strains, all animals remained clinically healthy. Results indicate that colonisation capacity is an important virulence determinant in rabbit staphylococcosis.
Administration, Intranasal↗
Differentiation between high and low virulence Staphylococcus aureus strains from rabbits by randomly amplified polymorphic DNA (RAPD) analysis.
Randomly Amplified Polymorphic DNA (RAPD) typing was performed on 53 rabbit Staphylococcus aureus strains. Twenty-three strains isolated in 13 different rabbitries with chronic problems of staphylococcosis, showed the same RAPD banding pattern. Twenty of these strains belonged to the 'mixed CV-C' biotype and to the phage-type 3A/3C/55/71, previously described to be highly virulent in rabbits, and three strains belonged to other biotypes or phage-types. None of the strains isolated from rabbitries without chronic problems of staphylococcosis showed this specific RAPD pattern. RAPD analysis can be used as a rapid and reliable test method to differentiate between the characteristic genotype corresponding to high virulence and other S. aureus strains from rabbits. This is useful for the diagnosis and prevention of the introduction of these highly virulent strains in industrial rabbitries.
Animals↗
Occurrence of Salmonella in tortoises in a rescue centre in Italy.
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Animals↗
Optimal development of Chlamydophila psittaci in L929 fibroblast and BGM epithelial cells requires the participation of microfilaments and microtubule-motor proteins.
The cytoskeleton is involved in several cellular activities, including internalization and transport of foreign particles. Although particular functions to each cytoskeleton component have been described, interactions between those components seem to occur. The involvement of the different host cell cytoskeletal components in uptake and development of Chlamydophila psittaci is incompletely understood. In this study, the participation of the microfilament network along with the kinesin and dynein microtubule motor proteins in the internalization and further development of Chlamydophila psittaci were investigated in L929 fibroblast and BGM epithelial cells. Cytochalasin D disruption of actin filaments, and blockage of the motor proteins through the introduction of monoclonal antibodies into the host cells were carried out, either single or combined, at different moments around bacterial inoculation, and Chlamydophila infectivity determined 24 h post- inoculation by direct immunofluorescence. Our results show that, although Chlamydophila Ipsittaci can make use of both microfilament-dependent and independent entry pathways in both cell types, Chlamydophila internalization and development in the fibroblast cells mainly concerned processes mediated by microfilaments while in the epithelial cells mechanisms that require microtubule motor proteins were the ones predominantly involved. Evidence that mutual participation of the actin and tubulin networks in both host cells are required for optimal growth of Chlamydophila psittaci is also presented.
Actins↗
Interaction between turkey monocytes and avian Chlamydia psittaci in the presence of Mycoplasma sp.: the importance of nitric oxide.
The interaction between Chlamydia psittaci and turkey monocytes was studied in vitro. Purified monocytes were inoculated with C. psittaci, in the presence or absence of Mycoplasma hyorhinis. Whereas turkey monocytes produced high amounts of nitric oxide (NO) following the inoculation with M. hyorhinis, inoculation with C. psittaci did not induce NO production in these phagocytes. The monocytes strongly supported chlamydial growth, as demonstrated by the presence of inclusion forming units, the positive direct immunofluorescence staining and transmission electron microscopy. In contrast, upon co-inoculation of the monocytes with C. psittaci and M. hyorhinis, a reduced replication rate of C. psittaci was observed. N(G)-monomethyl-L-Arginine, a competitive inhibitor for the enzyme NO-synthase, inhibited the NO production and reversed the antichlamydial activity of the M. hyorhinis co-inoculated turkey monocytes. These results imply two considerations. First, as chlamydiae are obligate intracellular bacteria, special care should be taken to guard chlamydial cultures from mycoplasmal contamination, in order to prevent false results when investigating the response of immunomodulating cells to chlamydial infection. Secondly, as a mycoplasmal co-infection in vitro has the capacity of inducing antichlamydial activity in turkey monocytes, through the action of NO, it could be suggested that a similar interaction might take place in vivo. Moreover, it was shown that avian M. gallisepticum strains were also able to induce NO in turkey monocytes. Considering the high prevalence of both C. psittaci and Mycoplasma sp. in turkeys, this interaction, through the pivotal role of NO, might influence the outcome of respiratory diseases in turkeys.
Animals↗
Genomic fingerprinting of pigeon Streptococcus gallolyticus strains of different virulence by randomly amplified polymorphic DNA (RAPD) analysis.
Randomly amplified polymorphic DNA (RAPD) analysis was performed on 95 pigeon S. gallolyticus strains of different virulence and belonging to different biotypes and different culture supernatant phenotypes as determined by SDS-PAGE. Four distinct RAPD patterns, designated A, B, C and D, were distinguished using primer OPM6 (5'CTGGGCAACT). All 76 strains generating RAPD pattern A or B were designated highly virulent on the basis of their SDS-PAGE pattern. Five of seven strains generating RAPD pattern C and 11 of 12 strains generating RAPD pattern D belonged to the moderately virulent and low virulent culture supernatant phenotype groups, respectively. Only one RAPD group C strain belonged to a highly virulent culture supernatant phenotype group. There was a correlation between biotype and RAPD patterns. These findings indicate that there is a high correlation between RAPD pattern and virulence for pigeons. Therefore, RAPD typing seems a rapid, reliable method to distinguish pigeon S. gallolyticus strains of high, moderate and low virulence.
Animals↗
Dynamics of the development of Chlamydophila psittaci inclusions in epithelial and fibroblast host cells.
The development of Chlamydophila psittaci (formerly Chlamydia psittaci, avian strains) inclusions in fibroblast L-929 and epithelial BGM cell lines was studied along the bacterial growth cycle using a BGM cell-adapted strain in the presence or absence of cycloheximide and cycloheximide + polyethylene glycol. Evolution of the inclusions was determined in terms of their number and size at 24, 30, 36, 48 and 54 h after infection. Significant differences in the chlamydial growth were found between both host cells, throughout the study. Higher numbers of inclusions (P < 0.05) were observed in L cells while larger inclusions (P < 0.01) were found in BGM cells. In both fibroblast and epithelial cells, inclusions showed a significant (P < 0.001) increase in size at the later times studied. Free extracellular chlamydial particles were noticed at 48 and 54 h post-infection (p.i.) in infected L cells, and at 54 h p.i. in BGM cells. Addition of cycloheximide or cycloheximide + polyethylene glycol had no significant effect on the number of inclusions or their size. The results suggest that host cell characteristics and innate compatibility between Chlamydophila strain and host cell are more important than host cell adaptation for the development of the microorganism.
Animals↗
Difficulties in experimental infection studies with Flavobacterium psychrophilum in rainbow trout (Oncorhynchus mykiss) using immersion, oral and anal challenges.
This study was carried out in order to try to establish an efficacious and reliable experimental infection model for Flavobacterium psychrophilum, the causative agent of rainbow trout fry syndrome, using contact, oral and anal challenges. Ten F psychrophilum strains of different origin were included. The influence of water temperature, scarification, water quality, stress and growth conditions of the pathogen on the experimental infection was assessed. For each challenge protocol, all strains failed to reproduce disease signs or mortality in rainbow trout (Oncorhynchus mykiss L.) fry. Histological and bacteriological examination of the skin, gills and internal organs of the fish 3 weeks following inoculation were found to be negative. Different hypotheses to explain the inability of the challenge models to reproduce the disease experimentally are discussed.
Animals↗
Incomplete cross resistance against ionophores in Enterococcus faecium and Enterococcus faecalis strains from pigs and poultry.
Thirty-two Enterococcus faecium strains and 33 Enterococcus faecalis strains were tested for their susceptibility to the ionophore antibiotics salinomycin, narasin, monensin, and lasalocid. Enterococcal strains originated from poultry in which these products are in use as coccidiostats, and from pigs in which these products are allowed as growth promoters. Resistance against salinomycin and narasin in enterococci was frequent among poultry strains, whereas in pig strains, resistance was less common. No resistance was found against monensin and lasalocid. Full cross resistance between salinomycin and narasin was evident. There was no cross resistance between these two ionophores and monensin and lasalocid.
Animals↗
Influence of different medium components on the in vitro activity of the growth-promoting antibiotic flavomycin against enterococci.
The growth-promoting antibiotic flavomycin (also called bambermycin, flavophospholipol and moenomycin) has a complex spectrum of activity against enterococci, with some species being naturally resistant and others susceptible. In this study, proteins added to Mueller-Hinton II medium had a strong deleterious effect on the activity of flavomycin, glucose had no effect and starch decreased the activity of flavomycin. The fatty substances Tween 80 and tributyrin increased the activity of flavomycin for several enterococcal species. Slight differences in the composition of the susceptibility test medium affected the MIC results obtained, indicating that strict standardization of the test medium is necessary.
Animals↗
Application of tRNA intergenic spacer PCR for identification of Enterococcus species.
tRNA intergenic spacer PCR (tDNA-PCR) was evaluated for its usefulness in the differentiation of enterococcal species of human and animal origin. This technique was carried out for 124 strains belonging to 17 enterococcal species and generated DNA fragments, which were separated by capillary electrophoresis. tDNA-PCR enabled us to discriminate for all species tested. Enterococcus faecium showed minor but reproducible differences with Enterococcus durans, while Enterococcus hirae was easily distinguishable. Enterococcus avium, Enterococcus malodoratus, and Enterococcus raffinosus generated highly similar though distinctive patterns.
Animals↗
Acinetobacter baumannii-infected vascular catheters collected from horses in an equine clinic.
Acinetobacter baumannii was isolated from tips clipped from seven intravenous jugular catheters collected from horses in the Ghent University equine clinic. They originated from seven different horses. Three of the seven showed evidence of local infection.
Acinetobacter↗
Identification of Corynebacterium glucuronolyticum strains from the urogenital tract of humans and pigs.
Bacterial strains isolated from the genital tracts of humans (predominantly males), semen of boars, and uterine and vaginal secretions of sows were identified as Corynebacterium glucuronolyticum and were compared with the type strains of the recently proposed species Corynebacterium glucuronolyticum and Corynebacterium seminale. The two type strains as well as the clinical strains were shown by DNA-DNA hybridization and sequencing of the 16S rRNA gene to be related at the species level. All strains were classified as C. glucuronolyticum, because this name has nomenclatural priority over C. seminale.
Animals↗
Detection of "Candidatus Helicobacter suis" in gastric samples of pigs by PCR: comparison with other invasive diagnostic techniques.
Recently, a new 16S ribosomal DNA-based PCR assay was developed for the specific detection of "Candidatus Helicobacter suis" (former "Gastrospirillum suis") in porcine gastric samples. In the present study, this PCR assay was compared to three other invasive diagnostic methods (rapid urease test, immunohistochemistry, histologic analysis by Giemsa staining). Antral stomach samples from 200 slaughterhouse pigs from Belgium and The Netherlands were examined. Bacterial presence was determined in 77% (154 of 200) of the samples by PCR in combination with Southern blot hybridization, 56% (111 of 200) of the samples by immunohistochemistry, 61% (122 of 200) of the samples by urease testing (20 h postinoculation [p.i.]), 36% (71 of 200) of the samples by urease testing (3 h p.i.), and 33% (65 of 200) of the samples by Giemsa staining. The intrinsic specificity of the PCR assay was assessed by Southern blot analysis with an "Candidatus H. suis"-specific probe and sequencing of PCR products. Interassay sensitivity and specificity values were assessed for each test by pairwise comparisons between tests. Agreement between tests was evaluated by calculating Cohen's kappa coefficient. From that analysis, the PCR assay was considered the most reliable benchmark. Microscopic detection of immunohistochemically labeled or Giemsa-stained "Candidatus H. suis" cells in stomach sections proved to be highly specific (100%) but relatively insensitive (72 and 42%, respectively) compared to the PCR assay. A longer incubation time of the urease test improved its sensitivity considerably (74 versus 55%) but was accompanied by a loss of specificity (72 versus 93%). In conclusion, we found the "Candidatus H. suis"-specific PCR assay to be a sensitive and reliable diagnostic method for the detection of "Candidatus H. suis" in the stomachs of pigs and could prove to be a valuable tool for further epidemiological studies both for "Candidatus H. suis"- and for "Helicobacter heilmannii" type 1-related research.
Animals↗
Early in vivo interactions of Actinobacillus pleuropneumoniae with tonsils of pigs.
Twenty gnotobiotic piglets were inoculated with 5 x 10(8) colony forming units of an Actinobacillus pleuropneumoniae biotype 1-serotype 9 strain onto their tonsils. Five other piglets (controls) were inoculated with phosphate-buffered saline solution. Pigs were euthanized at 30 min, 90 min, 180 min, 6 h, 9 h, 12 h or 24 h after inoculation. At necropsy, samples were taken from the tonsils for bacteriological, histological, immuno-histochemical and electron microscopical examination. A. pleuropneumoniae was isolated from tonsils of all the infected pigs, but not from tonsils of the control pigs. Early after inoculation bacteria were mainly associated with the stratified squamous epithelium and detached epithelial cells. Vacuolization and desquamation of the epithelium was observed and many transmigrating neutrophils were present. At later times after inoculation, bacteria were found closely associated with the crypt-walls and with detached cells present in the crypts. A strong neutrophil migration was observed mainly in the deeper parts of the crypts. It is concluded that attachment of A. pleuropneumoniae to tonsillar epithelial cells probably constitutes a first step in establishing bacteria at this body site.
Actinobacillus Infections↗
The association of Flavobacterium columnare strains of high and low virulence with gill tissue of black mollies (Poecilia sphenops).
The ability of a high virulence strain (AJS 1) and a low virulence strain (AJS 4) of Flavobacterium columnare (Flexibacter columnaris) to attach to the gills of black mollies (Poecilia sphenops) was investigated. For that purpose, two groups of 25 black mollies each were immersed in a bath containing 10(6) CFU/ml of F. columnare AJS 1 or AJS 4. At regular intervals from 1 to 12 h after the contact infection, fish were sacrificed and gills, skin, spleen and heart were sampled for bacteriology. Samples of the gills were taken for immunohistochemical and electron microscopic examination. Bacteriological examination proved that the number of gill-associated F. columnare was higher for AJS 1 than for AJS 4. Strain AJS 1 was isolated from the heart and spleen of 6 and 1 of the 16 examined animals, respectively. Strain AJS 4 was not isolated from the internal organs of any fish. When examined immunohistochemically, strain AJS 1 was found closely associated with gill epithelium whereas this was not the case for strain AJS 4. The adherence of bacteria to the gill tissue challenged with the virulent strain AJS 1 was also clearly demonstrated using scanning and transmission electron microscopy. These results indicate that adhesion of F. columnare to the gill tissue constitutes an important step in pathogenesis.
Animals↗