Leçon publique : "Quorum-sensing chez les bactéries ou quand les bactéries dialoguent"

Post doctoral thesis (2003)

Thèse principale : "Les souches nécrotoxinogènes d'Escherichia coli (NTEC) animales et humaines : identification et comparaison des propriétés générales et potentielles de virulence"

Post doctoral thesis (2003)

Virulence factors and specific properties of invasive Escherichia coli: III. Toxin production

in Annales de Médecine Vétérinaire (2003), 147(5, OCT-NOV), 327-342

Escherichia coli bacterial species is subdivided into several strains that are pathogenic for man and animals, on the basis of their specific properties and factors which are responsible for their ... [more ▼]

Escherichia coli bacterial species is subdivided into several strains that are pathogenic for man and animals, on the basis of their specific properties and factors which are responsible for their pathogenic characters. The pathogenic strains are classically subdivided into strains with intestinal tropism (enterotoxigenic, enteropathogenic, enterohaemmorrhagic, verotoxigenic and enteroinvasive) and with extraintestinal tropism (uropathogenic and invasive). Invasive strains cause septicaemia and/or bacteraemia with localisations in different internal organs (systemic infections). If specific virulence properties and factors of strains with intestinal tropism are quite well known and described, those of strains with extraintestinal tropism are much less characterised, especially in animals. The purpose of this serie of review articles is to present the current knowledge on specific properties and factors of extraintestinal strains: adhesins and colonisation factors, transmucosal transfer and survival in blood and internal organs, toxicity. The fourth manuscript will deal with the invasive strains themselves, focusing on the necrotoxigenic strains. This third manuscript presents the current knowledge on toxins produced by invasive strains of E. coli: endotoxins, cytotoxic necrotising factors, cytolethal distending toxins and haemolytic toxins. [less ▲]

Virulence factors and specific properties of invasive Escherichia coli: I. Adhesins and colonisation factors

in Annales de Médecine Vétérinaire (2003), 147(2, APR-MAY), 105

Escherichia coli bacterial species is subdivided into several strains that are pathogenic for man and animals, on the basis of their specific properties and factors which are responsible for their ... [more ▼]

Escherichia coli bacterial species is subdivided into several strains that are pathogenic for man and animals, on the basis of their specific properties and factors which are responsible for their pathogenic characters. The pathogenic strains are classically subdivided into strains with intestinal tropism (enterotoxigenic, enteropathogenic, enterohaemmorrhagic, verotoxigenic and enteroinvasive) and with extraintestinal tropism (uropathogenic and invasive). Invasive strains cause septicaemia and/or bacteraemia with localisations in different internal organs (systemic infections): If specific virulence properties and factors of strains with intestinal tropism are quite well known and described, those of strains with extraintestinal tropism are much less characterised, especially in animals. The purpose of this serie of review articles is to present the current knowledge on specific properties and factors of extraintestinal strains: adhesins and colonisation factors, transmucosal transfer and survival in blood and internal organs, toxicity. The fourth manuscript will deal with the invasive strains themselves, focusing on the necrotoxigenic strains. This first manuscript presents the current knowledge on the receptors, roles in pathogenesis, structures, genetic determinism and identification methods of fimbrial adhesins of P (Pap, Prs), S (Sfa, F1C, Sfr) and F17 (Vir, Att25, FY, 20K, G, Att111) families and of afimbrial adhesins of Afa family (Afa, Nfa, F1845, Bma, Dr...). [less ▲]

Prevalence and identity of cdt-related sequences in necrotoxigenic Escherichia coli

in Veterinary Microbiology (2003), 94

Isolation of Mycoplasma species from the lower respiratory tract of healthy cattle and cattle with respiratory disease in Belgium

in Veterinary Record (2002), 151(16), 472-476

Between 1997 and 2000, a total of 150 healthy cattle and 238 animals with respiratory disease were examined for six Mycoplasma species. Attempts were made to detect Mycoplasma canis, Mycoplasma dispar and ... [more ▼]

Between 1997 and 2000, a total of 150 healthy cattle and 238 animals with respiratory disease were examined for six Mycoplasma species. Attempts were made to detect Mycoplasma canis, Mycoplasma dispar and Ureaplasma diversum in calves with recurrent disease, and all three of these species were identified in calves with recurrent disease and in healthy lungs. In healthy calves, 84 per cent of bronchoalveolar lavage fluids were mycoplasma free; when cultures were positive, Mycoplasma bovirhinis was the only species isolated. Mycoplasmas were isolated from 78 per cent of animals suffering recurrent respiratory disease and from 65 per cent of acute respiratory cases. Mycoplasma bovis was isolated from bronchoalveolar lavages from 35 per cent of calves suffering recurrent respiratory disease, and from 50 per cent of acute cases, and from 20 per cent of pneumonic cases examined postmortem. M bovis was associated with other Mycoplasma species in 44 per cent of cases. M dispar was also isolated from 45.5 per cent of calves suffering recurrent respiratory disease, often in association with M bovis. M canis was identified for the first time in diseased Belgian cattle. Other mycoplasmas, including Mycoplasma arginini, Mycoplasma alkalescens and U diversum, were isolated less frequently. Associations between mycoplasmas and other pathogens were often observed. Among lungs infected with Pasteurella and/or Mannheimia species, more than 50 per cent were mixed infections with M bovis. [less ▲]

Septicémie à Edwardsiella tarda: rapport de deux cas chez le marsouin commun (Phocoena phocoena)

Poster (2002, September 05)

Comparison of sampling procedures for isolating pulmonary mycoplasmas in cattle

in Veterinary Research Communications (2002), 26(5), 333-339

Three sampling procedures were compared to determine the optimal technique for isolating mycoplasmas in cattle with respiratory diseases. The prevalence of mycoplasmas isolated from these animals is also ... [more ▼]

Three sampling procedures were compared to determine the optimal technique for isolating mycoplasmas in cattle with respiratory diseases. The prevalence of mycoplasmas isolated from these animals is also reported. In the first group, bronchoalveolar lavage (BAL) and nasal swab cultures were compared with the corresponding lung cultures from cattle necropsied for fatal respiratory diseases (n = 20). In a second group, nasal swabs were compared with corresponding BAL cultures in living animals with recurrent respiratory pathologies (n = 49). There was complete agreement between the paired BAL and lung cultures. In contrast, nasal cultures were not representative of the mycoplasmas present in the lower respiratory airways. The relative sensitivity and specificity of the nasal swab technique compared to BAL in living animals confirmed that the nasal swab cultures were not predictive of lower respiratory airway pathogens, such as Mycoplasma bovis. BAL is considered to be the best method for isolating M. bovis in cattle with respiratory diseases as it combines reliability and feasibility under field sampling conditions. In the present study, Mycoplasma dispar (43%) and M. bovis (29%) were mainly isolated in mixed infections. This confirms the need to search for mycoplasmas in routine examinations and to take them into account in therapeutic strategies for respiratory diseases in cattle. [less ▲]

Examination of Escherichia coli from poultry for selected adhesin genes important in disease caused by mammalian pathogenic E-coli

in Veterinary Microbiology (2002), 84(3), 231-241

A collection of 1601 extraintestinal and intestinal Escherichia coli isolated from chickens, turkeys and ducks. in Belgium, France and Spain, was hybridised with gene probes specific for fimbrial and ... [more ▼]

A collection of 1601 extraintestinal and intestinal Escherichia coli isolated from chickens, turkeys and ducks. in Belgium, France and Spain, was hybridised with gene probes specific for fimbrial and afimbrial adhesins (F17, F18, S (Sfa/F1C), Bfp, Afa, Cs31A, Intimin (Eae), Aida-1) of intestinal, urinary and invasive E. coli of mammals and with a probe specific for the P (Pap/Prs) fimbrial adhesin of urinary and invasive E. coli of mammals and birds. Three hundred and eighty-three strains (23.9%) were P-positive, 76 strains (4.8%) were Afa-positive, 75 strains (4.7%) were F17-positive, 67 strains (4.2%) were S-positive, 23 (1.4%) were Intimin-positive. and all were F18-, Cs31A-, Aidal- and Bfp-negative. The 75 F17-positive strains harboured different major subunit A-encoding gene variants, but the f17Ac variant was the most frequent (52 strains, 69,3%) and seven strains (9.3%) were not typeable. The f17G gene variant coding for the GII adhesin was the most frequent (56 strains, 75.0%), whereas the f17GI gene variant was present in four strains (5%) and 15 strains (20.0%) were not typeable. All Afa-positive strains harboured the afa-8 variant. The 23 Intimin-positive E. coli tested positive for the beta -variant (16 strains; 69.6%) or for the gamma -variant (seven strains;, 30.4%) of the eae gene. Chicken and turkey E. coli were more frequently probe-positive (43.6 and 43.1 %, respectively) than duck E. coli 31.5%) and extraintestinal E. coli were also more frequently probe-positive (48.4%) than intestinal strains (18.5%). Different combinations of probe positive hybridisation results were observed in 72 of the 540 probe-positive E. coli (13.3%). The most frequent combinations were between AfaE-8 and F17 probes (47 strains; 8.7%) and between P and S probes (13 strains. 2.4%). Although f17- and afa-8-related DNA sequences can be plasmid-located in mammalian E. coli. they were not in avian E. coli. Besides the P fimbrial adhesin, F17 and S fimbrial and Afa-VIII and Intimin afimbrial adhesins may thus represent colonisation factors of avian pathogenic E. coli. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

Pathogenic Escherichia coli strains from dogs and cats : IV) - General discussion

in Annales de Médecine Vétérinaire (2002), 146(4, AUG-SEP), 219

This manuscript reviews the current knowledge on the main classes of pathogenic Escherichia coli in dogs and cats: type 1 necrotoxigenic strains (NTEC1), adhesin-positive strains (AdEC), enteropathogenic ... [more ▼]

This manuscript reviews the current knowledge on the main classes of pathogenic Escherichia coli in dogs and cats: type 1 necrotoxigenic strains (NTEC1), adhesin-positive strains (AdEC), enteropathogenic strains (EPEC) and enterotoxigenic strains (ETEC). They represent primary or secondary (to other bacterial, parasitic and/or viral infections) infectious agents. NTEC1 and AdEC are the most frequent and are responsible for intestinal, urinary tract and invasive infections, while EPEC and ETEC limit their infections to the intestinal tract. ETEC are the less frequent but EPEC are more and more often observed. The specific virulence factors and other properties of these pathogenic E. coli strains are similar to those of their bovine, human and porcine counterparts, for their identity and their genetic determinism. This similarity allows the use of an identical approach in their diagnosis and typing. But for some NTEC1, AdEC and EPEC strains the similarity is so close that it also raises the question of their zoonotic potential, though there is up to now no epidemiological evidence of such cross contamination of man by canine or feline pathogenic E. coli (or vice versa). [less ▲]