Freddy Haesebrouck

Prevalence of dermatophytes in asymptomatic guinea pigs and rabbits.

References BEDFORD, P. G. C. (1999) Diseases and surgery of the canine eyelids. In Veterinary Ophthalmology. 3rd edn. Ed K. N. Gelatt. Philadelphia, Lippincott, Williams & Wilkins. pp 535-568 BRIGHTMAN,A. H. (1993) Eyelids. In Textbook of Small Animal Surgery.Vol 2. 2nd edn. Ed D. Slatter. Philadelphia, W. B. Saunders. pp 1157-1177 GELATT, K. N. & GELATT, J. P. (1994) Surgical procedures for entropion. In Handbook of Small Animal Ophthalmic Surgery. Vol 1: Extra-ocular Procedures. New York, Pergamon. pp 87-98 MOORE, C. P. & CONSTANTINESCU, G. M. (1997) Surgery of the adnexa. In Veterinary Clinics of North America, Surgical Management of Ocular Disease. Ed M. P. Nassisse. Philadelphia, W. B. Saunders. pp 10111066

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.

Antibiotic sensitivity and resistance in Ornithobacterium rhinotracheale strains from Belgian broiler chickens

Establishing the antibiotic sensitivity of the avian respiratory pathogen Ornithobacterium rhinotracheale is difficult because of the organisms complex growth requirements and the unusually frequent occurrence of resistance. The minimal inhibitory concentrations of 10 antibiotics were determined for 45 strains of O. rhinotracheale from Belgian broiler chickens collected from 45 farms between 1995 and 1998. They were compared with the type strain, which was isolated from a turkey, and a strain isolated from a rook. All the broiler strains were resistant to lincomycin and to the β -lactams ampicillin and ceftiofur. Less than 10% of the strains were sensitive to the macrolides tylosin and spiramycin, tilmicosin and flumequine. A few strains were sensitive to enrofloxacin and doxycycline. All strains were sensitive to tiamulin.

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.

Ultrastructure of surface components of Streptococcus gallolyticus (S. bovis) strains of differing virulence isolated from pigeons

Virulence of Streptococcus gallolyticus (S. bovis) strains isolated from pigeons is associated with the presence of the extracellular proteins A, T1, T2 and T3. Based on the presence or absence of these proteins, six supernatant-phenotypes are distinguished. Experimental infection studies have indicated that strains belonging to the A-T1, A+T1, A+T2 and A+T3 groups are highly virulent for pigeons, strains belonging to the A-T3 groups are moderately virulent and A-T2 strains are of low virulence. In this study the surface structure of 15 pigeon S. gallolyticus strains representing high, moderate and low virulence supernatant-phenotypes was examined by electron microscopy. The presence of capsular material was determined by transmission electron microscopy after polycationic ferritin labelling and immunostabilization. Capsules from cells labelled with polycationic ferritin were usually thicker than those from cells exposed to antiserum. The capsule of the virulent strains had a regular, continuous appearance whilst irregularity of the capsule was a characteristic of the low virulence A-T2 strains. Negative staining revealed the presence of fimbriae in all strains belonging to the high virulence A-T1, A+T1, A+T2 and A+T3 supernatant groups and in one strain of the moderately virulent A-T3 group. The fimbriae were thin, flexible structures with a diameter of approximately 3-4 nm and a length of up to 700 nm. Fimbriae as described above were absent in two other A-T3 strains examined and in the low virulence A-T2 strains. Results from this study indicate that morphological differences in surface structure exist among virulent and low virulence pigeon S. gallolyticus strains, and that the capsule and/or fimbriae are possibly involved in virulence.

Experimental Streptococcus bovis infections in pigeons

Thirty pigeons were experimentally infected with Streptococcus bovis using an intravenous infection model. Ninety percent of the inoculated pigeons developed clinical disease. Disease signs included acute death, inability to fly, lameness, inappetence, emaciation, polyuria, and the production of slimy, green droppings. At necropsy, the septicemic character of the disease was evident. Typical lesions included extensive well-circumscribed areas of necrosis in the pectoral muscle, tenosynovitis of the tendon of the Musculus pectoralis profundus, and arthritis of the stifle, tibiotarsal, or shoulder joints. Focal myocardial necrosis also was seen. Meningitis and encephalitis occurred in the cerebrum and the cerebellum. Disease signs and lesions described here after experimental infection were similar to those in naturally occurring cases of S. bovis septicemia.

Occurrence of Salmonella in tortoises in a rescue centre in Italy

enter sperm cells and oocytes. More recently, the proviral DNA of bovine immunodeficiency virus was detected in association with frozen bull semen, but the transmission ofthe virus to oocytes by infected sperm during fertilisation was not investigated (Nash and others 1995). Since the swim up procedure generates a practically clean motile sperm fraction which is free of other cells, it is conceivable that BLV becomes associated with some sperm cells and is carried through the zp into oocytes during fertilisation which most likely were resistant to the viral infection. Since all IVF embryos tested negative, it can be speculated that the sensitivity of the PCR was insufficient to detect the proviral DNA associated with a single sperm cell introduced into embryos during fertilisation. It is also possible that the proviral DNA was adversely affected by the incubation conditions of embryos during the eight days after fertilisation. Although in this study, all embryos tested negative for proviral DNA, it is advisable for IVF practitioners to use semen from bulls free of BLV. Also, in view of the fact that as little as 1 [d of BLV-infected blood can be sufficient to transmit the disease (Evermann and others 1986), efforts should be made to limit the amount of aspirated blood associated with the follicular fluid during oocyte retrieval, and special attention should be paid when washing embryos (Stringfellow and Seidel 1998). In conclusion, these results indicate that IVF embryos generated in the presence of BLV do not appear to be associated with infectious BLV, as previously demonstrated for in vivo produced embryos. However, experiments involving the transfer of IVF embryos are needed to verify these studies. Further studies on the interaction of BLV with sperm cells also appear to be warranted.

Cross-protection between Actinobacillus pleuropneumoniae biotypes-serotypes in pigs

Four groups of hysterectomy-derived and colostrum-deprived pigs were intranasally inoculated with an Actinobacillus pleuropneumoniae biotype 1-serotype 2 strain (producing RTX toxins ApxII and ApxIII. 6 pigs), an A. pleuropneumoniae biotype 1-serotype 10 strain (producing ApxI. 5 pigs), an A. pleuropneumoniae biotype 2-serotype 2 strain (producing ApxII, 5 pigs) or saline (controls, 7 pigs). All pigs were exposed to A. pleuropneumoniae biotype 1-serotype 2 endobronchial challenge. After challenge, severe clinical signs were observed in all control pigs, one pig immunized with the A. pleuropneumoniae biotype 1-serotype 10 strain and two pigs immunized with the A. pleuropneumoniae biotype 2-serotype 2 strain. These pigs died within 36 h after challenge and 20 to 50% of the lungs were macroscopically affected. In the other pigs, clinical signs were mild or absent and no or only small, focal lung lesions were observed when euthanized at 48 h after challenge. At the time challenge neutralizing antibodies against ApxI only. ApxII only and both ApxII and III were present in sera of pigs immunized with the A. pleuropneumoniae biotype 1-serotype 10 strain, the A. pleuropneumoniae biotype 2-serotype 2 strain and the A. pleuropneumoniae biotype 1-serotype 2 strain, respectively. These results indicate that immune mechanisms other than Apx neutralizing antibodies were involved in partial cross-protection of pigs immunized against A. pleuropneumoniae biotype 1-serotype 10 and challenged with the A. pleuropneumoniae biotype 1-serotype 2.

Pathogenesis of infections with Salmonella enterica subsp. enterica serovar Muenchen in the turtle Trachemys scripta scripta.

The pathogenesis of Salmonella enterica subsp. enterica serovar Muenchen infections in the aquatic turtle Trachemys scripta scripta was studied. After oral infection with 5x10(5)cfu of serovar Muenchen of 10-14-month-old turtles, kept at 26 degrees C, the intestine and especially the ileum, caecum and colon was colonized. Invasion of the intestinal wall, causing histopathological lesions, and colonization of internal organs were not observed. Serovar Muenchen was only isolated from turtles for 8 days after exposure. Keeping the turtles at 37 degrees C caused colonization of liver and spleen in two of six orally infected turtles and augmented the numbers of bacteria in the intestinal tract. In contrast to oral infections, intraperitoneal infections of turtles with serovar Muenchen enabled the bacterium to persist inside the host for at least 5 weeks. Clearance of serovar Muenchen from the liver and blood was more pronounced at 26 degrees C than at 37 degrees C. ELISA antibodies were demonstrated in intraperitoneally but not in orally infected turtles kept at 26 degrees C. In conclusion, the lack of persistence and invasiveness of serovar Muenchen in T. s. scripta after oral exposure might be due to the turtles relatively low body temperature and/or the absence of well-organized gut-associated lymphoid tissue.

Prevalence of streptococcus bovis in racing pigeons

The prevalence of S. bovis in the intestinal tract of healthy racing pigeons was determined. Crop and cloaca swab samples obtained from 810 pigeons from 14 different lofts and from 122 pigeons that were presented for routine health control were examined for the presence of S. bovis. Pooled faecal samples were also obtained from pigeons in 82 different pigeon lofts. S. bovis was isolated from crop or cloaca samples of approximately 40% of pigeons of all ages by direct culture and from 80% of the pooled faecal samples by enrichment culture. In a longitudinal study, crop and cloaca samples were collected every 3 months from pigeons in seven different pigeon lofts. The prevalence of S. bovis in these pigeons ranged from 0 to 100%. The carriage rate was not related to the season or to the age of the pigeons. The prevalence of S. bovis in organ lesions of pigeons examined at necropsy was investigated over a 35-month period. S. bovis was isolated from 10% of the birds examined. The incidence of S. bovis septicaemia was significantly higher in January to August than in September to December. It was concluded that S. bovis is an opportunistic pathogenic agent in pigeons.