Mycoplasma bovis shares insertion sequences with Mycoplasma agalactiae and Mycoplasma mycoides subsp mycoides SC: Evolutionary and developmental aspects

in FEMS Microbiology Letters (2005), 245(2), 249-255

Three new insertion elements, IS Mbov1, ISMbov2 and ISMbov3, which are closely related to ISMag1 (Mycoplasma agalactiae), ISMmy1 and IS1634 (both Mycoplasma in mycoides subsp. in mycoides SC ... [more ▼]

Three new insertion elements, IS Mbov1, ISMbov2 and ISMbov3, which are closely related to ISMag1 (Mycoplasma agalactiae), ISMmy1 and IS1634 (both Mycoplasma in mycoides subsp. in mycoides SC), respectively, have been discovered in Mycoplasma bovis, an important pathogen of cattle. Southern blotting showed that the genome of M. bovis harbours 6-12 copies of ISMbov1, 11-15 copies of ISMbov2 and 4-10 copies of ISMbov3, depending on the strain. A fourth insertion element, the IS30-like element, is present in 4-8 copies. This high number of IS elements in AI bovis, which represent a substantial part of its genome, and their relatedness with IS elements of both M. agalactiae and M. mycoides subsp. mycoides SC suggest the occurrence of two evolutionary events: (i) a divergent evolution into ill. agalactiae and M. bovis upon infection of different hosts; (ii) a horizontal transfer of IS elements during co-infection with M. mycoides subsp. mycoides SC and Ad. bovis of a same bovine host. (c) 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved. [less ▲]

Mycoplasma bovis shares insertion sequences with Mycoplasma agalactiae and mycoplasma mycoides subsp. mycoides: evolutionary and developmental aspects

in FEMS Microbiology Letters (2005), 245(2), 249-255

Three new insertion elements, ISMbov1, ISMbov2 and ISMbov3, which are closely related to ISMag1 (Mycoplasma agalactiae), ISMmy1 and IS1634 (both Mycoplasma mycoides subsp. mycoides SC), respectively, have ... [more ▼]

Three new insertion elements, ISMbov1, ISMbov2 and ISMbov3, which are closely related to ISMag1 (Mycoplasma agalactiae), ISMmy1 and IS1634 (both Mycoplasma mycoides subsp. mycoides SC), respectively, have been discovered in Mycoplasma bovis, an important pathogen of cattle. Southern blotting showed that the genome of M. bovis harbours 6-12 copies of ISMbov1, 11-15 copies of ISMbov2 and 4-10 copies of ISMbov3, depending on the strain. A fourth insertion element, the IS30-like element, is present in 4-8 copies. This high number of IS elements in M. bovis, which represent a substantial part of its genome, and their relatedness with IS elements of both M. agalactiae and M. mycoides subsp. mycoides SC suggest the occurrence of two evolutionary events: (i) a divergent evolution into M. agalactiae and M. bovis upon infection of different [less ▲]

A comparison of somatic cell count and antimicrobial susceptibility of subclinical mastitis pathogens in organic and conventional dairy herds

in Annales de Médecine Vétérinaire (2005), 149(3), 173-182

A comparison of somatic cell count and antimicrobial susceptibility of subclinical mastitis pathogens in organic and conventional dairy herds.Bovine subclinical mastitis is the most important disease ... [more ▼]

A comparison of somatic cell count and antimicrobial susceptibility of subclinical mastitis pathogens in organic and conventional dairy herds.Bovine subclinical mastitis is the most important disease affecting dairy cows. The fluctuating increase in somatic cell count (SCC) that occurs causes major economic losses in dairy industry. This comparative study between conventional and organic dairy herds was conducted in the aim to better characterize which consequences might have different management practices on SCC but also on the frequency of pathogens isolated and their antimicrobial susceptibility. Four conventional and four organic herds, with bulk milk SCC >300x103cells/ml were selected, in which respectively 47 and 44 cows were investigated. Each quarter was sampled 3 times at 15 days interval for SCC, microbiological analysis and antimicrobial susceptibility. In both herd categories, major pathogens isolated were by order of importance Streptococcus uberis, Staphylococcus aureus and Streptococcus dysgalactiae with a great impact on SCC. Coagulase negative staphylococci were the most frequent minor germs and had a moderated but real impact on SCC. In certified organic dairy farms, the three most frequently isolated major pathogens were significantly more susceptible to antimicrobials in vitro. This study suggests that the limited use of antibiotics in organic dairy herds could explain, at least in part, the lower resistance obtained from analysed isolates. [less ▲]

Synergistic action of E. coli endotoxin and Pasteurella multocida type A for the induction of bronchopneumonia in pigs

in Veterinary Journal (2005), 169(3), 417-426

This study aimed to investigate whether Escherichia coli endotoxin (LPS) may predispose the lung to an infection with Pasteurella multocida type A (Pma) and to determine the LPS concentration needed to ... [more ▼]

This study aimed to investigate whether Escherichia coli endotoxin (LPS) may predispose the lung to an infection with Pasteurella multocida type A (Pma) and to determine the LPS concentration needed to reproduce clinical signs of bronchopneumonia. Twenty-four hours before inoculating Pma or sterile growth medium, piglets were tracheally instilled with 10, 100 or 400 microg/kg LPS. Cough, body temperature, daily weight gain (DWG) bronchoalveolar lavage fluid (BALF) cells and volume of pneumonic lung were measured. Changes in breathing pattern (Penh) were assessed by whole body barometric plethysmography. No significant changes were observed in Pma-treated or in control animals. Each LPS doses induced DWG reduction while the higher generated a severe subacute interstitial pneumonia causing hyperthermia and an increase in Penh. The combination of the lower LPS doses with Pma produced an asymptomatic bronchopneumonia leading to DWG reduction, rise in Penh and an increase in BALF macrophages and neutrophils. With 400 microg/kg LPS, Pma worsened the inflammatory process as illustrated by cough, hyperthermia, major DWG reduction and by a greater Penh response. Lung lesions consisted of severe exudative bronchopneumonia. We concluded that LPS may negatively influence growth, predispose to persisting lung inflammatory process and promote Pma infection depending on the dose previously administered. [less ▲]

Verotoxigenic Escherichia coli from animals, humans and foods: who's who?

in Journal of Applied Microbiology (2005), 98(6), 1332-1344

Verocytotoxigenic (shigatoxigenic) and enterohaemorrhagic Escherichia coli, VTEC ( STEC) and EHEC, produce a toxin active on Vero cells in vitro. VTEC and EHEC have been isolated from humans and different ... [more ▼]

Verocytotoxigenic (shigatoxigenic) and enterohaemorrhagic Escherichia coli, VTEC ( STEC) and EHEC, produce a toxin active on Vero cells in vitro. VTEC and EHEC have been isolated from humans and different animal species, mainly ruminants and pigs. The verocytotoxins, also named shiga toxins (Stx), are active in vivo on the endothelial cells of the blood vessels of the gastro-intestinal mucosa, the kidneys, the brain, and other tissues of humans and piglets, leading to fluid leakage or haemorrhages. Conversely, their role in diseases of young ruminants remains unclear. Adult ruminants can also act as asymptomatic carriers of VTEC and EHEC strains similar to those causing diseases in humans. And they are incriminated as an important source of direct or indirect contamination of humans by the most famous EHEC strain belonging to the O157: H7 serotype, through faecal contamination of either foods of animal origin, or other foodstuffs ( fruit, vegetables, etc.), or the environment. But dozens of non-O157 human and ruminant VTEC and EHEC strains with similar general and virulence-associated properties, have been described, whose epidemiology is much less well understood. The purpose of this review manuscript is to describe and compare the properties of human, ruminant and food VTEC and EHEC strains. [less ▲]

DNA vaccination for the priming of neutralizing antibodies against non-immunogenic STa enterotoxin from enterotoxigenic Escherichia coli

in Vaccine (2005), 23(27), 3618-3627

Development of disease : bacterial toxins and their interaction with host cells

Conference given outside the academic context (2005)

Genetics and regulation of bacterial virulence: towards the molecular version of Koch's postulates

Conference given outside the academic context (2005)

The p40* adhesin pseudogene of Mycoplasma bovis

in Veterinary Microbiology (2004), 104(3-4), 213-217

An analogue of the adhesin gene p40 of Mycoplasma agalactiae was found in Mycoplasma bovis. Nucleotide sequence analysis of the p40* gene in M. bovis revealed the presence of a large deletion involving a ... [more ▼]

An analogue of the adhesin gene p40 of Mycoplasma agalactiae was found in Mycoplasma bovis. Nucleotide sequence analysis of the p40* gene in M. bovis revealed the presence of a large deletion involving a frameshift that causes premature truncation of the translated protein, indicating that p40* exists as a pseudogene in M. bovis. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

Pathogenicity of pap-negative avian Escherichia coli isolated from septicaemic lesions

in Microbes & Infection (2004), 6(7), 637-645

Recent studies by DNA-DNA hybridisation assays conducted on a large collection of Escherichia coli strains isolated from chickens, ducks and turkeys suffering from colibacillosis, showed that 76% of the ... [more ▼]

Recent studies by DNA-DNA hybridisation assays conducted on a large collection of Escherichia coli strains isolated from chickens, ducks and turkeys suffering from colibacillosis, showed that 76% of the strains were negative for the presence of the pap gene cluster. The objective of this paper was to study the virulence associated with the avian E. coli strains negative for the P fimbriae, but carrying the f17 or the afa-8 gene cluster coding for adhesins associated with strains pathogenic for mammals. Three strains carrying the f17 fimbriae and three carrying the afa-8 adhesin-encoding gene cluster were studied in three in vivo experimental models of avian colibacillosis: subcutaneous inoculation of 1-day-old chicks, inoculation of specific-pathogen-free (SPF) chickens via the intra-thoracic air sac, and intra-tracheal inoculation of axenic chickens. The results showed that the six P-negative E. coli isolates carrying the f17 or the afa-8 gene cluster were lethal for 1-day-old chicks. They were also able to reproduce clinical signs and lesions of colibacillosis (aerosacculitis, pericarditis, perihepathitis), with bacteraemia and septicaemia, in SPF chickens inoculated via the thoracic air sacs as well as in axenic chickens inoculated by the intra-tracheal route. Further studies with f17 and afa-8 allelic mutants constructed by disruption must be performed to confirm a role of F17 fimbrial and Afa-VIII afimbrial adhesins in the pathogenesis of avian colibacillosis. (C) 2004 Elsevier SAS. All rights reserved. [less ▲]