RESUMO
The genetic diversity and clonal relationships among 77 Escherichia coli strains isolated in France from diarrhoeic rabbits and that belonged to seven O serogroups including the predominant O103 serogroup, were estimated by ribotyping and random amplified polymorphic DNA (RAPD) assays. Fifteen ribotypes were defined. Most of the highly pathogenic O103 strains could be assigned to two major groups. Non-pathogenic strains were clearly distinguished. RAPD assays generally matched ribotyping, or gave more precision for subdividing strains from the two main O103 groups. The results on strains isolated from different areas and over a 9-year period showed the relevance of the association of these two methods for the survey of the spread of strains in breeding flocks and illustrated clonal diffusion in rabbit production structures.
Assuntos
Diarreia/veterinária , Infecções por Escherichia coli/veterinária , Escherichia coli/classificação , Escherichia coli/genética , Coelhos/microbiologia , Animais , Técnicas de Tipagem Bacteriana/veterinária , Sequência de Bases , Clonagem Molecular , Impressões Digitais de DNA/veterinária , Diarreia/microbiologia , Infecções por Escherichia coli/microbiologia , Variação Genética , Dados de Sequência MolecularRESUMO
Seventy selected strains of Salmonella typhimurium and S. enteritidis isolated from related poultry flocks in three independent geographical areas were characterized by phenotypic and genotypic methods to compare the usefulness of the methods in epidemiological studies. The 56 S. typhimurium isolates were poorly discriminated by their biotypes, resistance patterns, and plasmid profiles. Nine different ribotypes were obtained after DNA digestion by BglII, PvuII, and SmaI. Seven IS200 types, characterized by six to nine copies of IS200 on the chromosome, were detected after digestion of genomic DNA by PstI. These studies resulted in the definition of 15 clonal lineages distributed in three clusters. The 14 S. enteritidis strains were not discriminated either by ribotyping or by detection of IS200 (IS200 typing), but were separated on the basis of antibiotic resistance and plasmid profiling. The stability of the insertion sequence type was confirmed by inoculation of an S. typhimurium strain to axenic chickens reared for 15 weeks in sterile isolators.
Assuntos
Técnicas de Tipagem Bacteriana , Doenças das Aves Domésticas/epidemiologia , Salmonelose Animal/epidemiologia , Salmonella enteritidis/classificação , Salmonella typhimurium/classificação , Animais , Aves , Galinhas , Elementos de DNA Transponíveis/genética , DNA Ribossômico/genética , Resistência Microbiana a Medicamentos , Patos , França/epidemiologia , Plasmídeos/genética , Doenças das Aves Domésticas/microbiologia , Coelhos , Salmonelose Animal/microbiologia , Salmonella enteritidis/genética , Salmonella typhimurium/genética , PerusRESUMO
Seventy-one Escherichia coli strains isolated from diarrhoeic weaned rabbits from different areas of France were tested for the presence of DNA sequences specific for the EPEC, EHEC, DAEC and EAggEC strains and 16 of them were tested for pathogenicity in animal experiments. High pathogenicity was observed only with strains unable to ferment rhamnose. DNA from all 55 rhamnose-negative O103, O26 and rough strains hybridised with the eaeA probe. Similar hybridisation was obtained with six non-pathogenic rhamnose-positive strains belonging to serogroups O128 and O132. No hybridisation was observed with the other probes. This is the first report of the presence of eaeA sequences in genomic DNA of non-pathogenic strains.
Assuntos
Adesinas Bacterianas , Proteínas da Membrana Bacteriana Externa/genética , Proteínas de Transporte , Diarreia/veterinária , Infecções por Escherichia coli/veterinária , Proteínas de Escherichia coli , Escherichia coli/genética , Coelhos/microbiologia , Animais , Proteínas da Membrana Bacteriana Externa/química , Southern Blotting/veterinária , Contagem de Colônia Microbiana/veterinária , Sondas de DNA , DNA Bacteriano/análise , DNA Bacteriano/química , Diarreia/microbiologia , Escherichia coli/patogenicidade , Infecções por Escherichia coli/microbiologia , Fezes/microbiologia , Genes Bacterianos , Plasmídeos , Organismos Livres de Patógenos Específicos , DesmameRESUMO
A stock of Trichostrongylus colubriformis infective larvae (L3) was stored for up to 15 weeks at 24 degrees C. At three weeks intervals, samples of L3 were taken to assess exsheathment rate and enzyme activity Leucine Amino Peptidase (LAP) and Alkaline Phosphatase (AP). From 0 to 9 weeks of storage, a decrease in enzyme activity was observed correlated with a decrease in exsheathment rate (percentage of L3 exsheathed in vitro after 20 min); the maximum percentage of exsheathed larvae (L3 exsheathed after 180 min) was then 75%. From 9 to 15 weeks of storage, both enzyme activity and exsheathment rate were low and constant; the maximum percentage of exsheathed larvae never exceeded 30%. The role of enzymes in the mechanism of exsheathment is discussed.
Assuntos
Fosfatase Alcalina/metabolismo , Leucil Aminopeptidase/metabolismo , Trichostrongylus/fisiologia , Animais , Larva/fisiologia , Fatores de Tempo , Trichostrongylus/enzimologiaRESUMO
Infective larvae of two trichostrongyle parasites of the small intestine were stored from 0 to 22 weeks at 24 degrees C for T colubriformis and from 0 to 82 weeks at 4 degrees C for H polygyrus. A loss in infectivity with ageing was observed in vivo as well as a decrease in the exsheathment potential (number of larvae exsheathed in vitro after 20 min of incubation). A linear regression was established between the number of larvae exsheathed in vitro within 20 min and the number of adult worms developed in vivo.