RESUMEN
The clinical and microbial efficacy of antimicrobial treatments of avian colibacillosis was studied, using an experimental model on chickens previously inoculated with multiresistant commensal Escherichia coli strains. One E. coli with pMG252 plasmid containing bla(FOX5) and qnrA1 genes and another E. coli with pMG298 plasmid containing bla(CTX-M15) and qnrB1 genes were first orally inoculated to chickens Both isolates were also resistant to chloramphenicol, sulphamethoxazole, trimethoprim, streptomycin, gentamicin, kanamycin, and tetracycline. The birds were then experimentally infected with an avian pathogenic E. coli (APEC), via the air sac. Treatments (oxytetracycline (OTC), trimethoprim-sulfadimethoxin (SXT), amoxicillin (AMX) or enrofloxacin (ENR) were then offered at the therapeutic doses. Symptoms, lesions in dead or sacrificed birds, and isolation and characterization of APEC from internal organs were studied. Results showed that OTC, SXT or ENR treatments could control the pathology. AMX worsened the disease, possibly due to endotoxin shock. All APEC re-isolated from internal organs showed the same antimicrobial susceptibility as the APEC inoculated strain, except for one APEC isolate from an infected OTC-treated bird, which acquired tetracycline resistance only, and one APEC isolate recovered from the air sacs of a chicken in the infected SXT-treated group, which acquired the pMG252 plasmid and became multi-resistant. Thus three antimicrobials could control the disease but the experimental model enabled, to our knowledge, the first observation of plasmid transfer from a bacterium of the intestinal tract to a pathogenic isolate from the respiratory tract.
Asunto(s)
Antibacterianos/uso terapéutico , Pollos/microbiología , Infecciones por Escherichia coli/veterinaria , Escherichia coli/efectos de los fármacos , Enfermedades de las Aves de Corral/tratamiento farmacológico , Amoxicilina/efectos adversos , Animales , Farmacorresistencia Bacteriana , Enrofloxacina , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Infecciones por Escherichia coli/tratamiento farmacológico , Infecciones por Escherichia coli/microbiología , Femenino , Fluoroquinolonas/uso terapéutico , Masculino , Oxitetraciclina/uso terapéutico , Plásmidos , Enfermedades de las Aves de Corral/microbiología , Sulfadimetoxina/uso terapéutico , Trimetoprim/uso terapéuticoRESUMEN
The aim of this assay was to develop an experimental model of digestive colonization of chickens with bacteria harboring qnr, extended-spectrum beta-lactamase, or ampC genes. Specific pathogen-free chickens were orally inoculated with two Escherichia coli strains containing either the plasmid pMG252 bearing bla(FOX) and qnrA genes, or pMG298 bearing bla(CTX-M) and qnrB genes. Analysis of strains isolated from fecal samples showed that the two strains were able to persist for several weeks in the digestive flora of inoculated birds and could rapidly spread to noninoculated ones. However, the multi-resistant isolates were maintained as a small proportion of the overall enterobacterial population. The qnr, extended-spectrum beta-lactamase, and ampC resistance genes could be transferred, in vivo, in the absence of selective pressure, to other chicken E. coli or Klebsiella pneumoniae isolates.
Asunto(s)
Proteínas Bacterianas/genética , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Tracto Gastrointestinal/microbiología , beta-Lactamasas/genética , Animales , Pollos , Modelos Animales de Enfermedad , Farmacorresistencia Bacteriana Múltiple , Escherichia coli/aislamiento & purificación , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/aislamiento & purificación , Plásmidos , Factores de TiempoAsunto(s)
Enterococcus , Infecciones por Bacterias Grampositivas/epidemiología , Infecciones por Bacterias Grampositivas/veterinaria , Enfermedades de las Aves de Corral/epidemiología , Enfermedades de las Aves de Corral/microbiología , Enfermedades de los Porcinos/epidemiología , Enfermedades de los Porcinos/microbiología , Resistencia a la Vancomicina , Mataderos , Animales , Medios de Cultivo , Enterococcus/efectos de los fármacos , Enterococcus/genética , Heces/microbiología , Francia/epidemiología , Infecciones por Bacterias Grampositivas/microbiología , Resistencia a la Vancomicina/genéticaRESUMEN
Campylobacter fetus causes severe infections in humans and can be isolated from various mammals and reptiles. However, although poultry are considered to be the main reservoir of Campylobacter jejuni, little is known about the presence of C. fetus in poultry. Thus, specific pathogen-free chickens were experimentally inoculated with a mixture of either three non-thermotolerant or four thermotolerant human strains of C. fetus. Faecal samples were regularly sampled after inoculation and caeca and intestines were collected 21 or 40 days after inoculation. All samples were analysed for the presence of Campylobacter using culture techniques. No Campylobacter could be re-isolated. This result strongly suggests that broilers do not play an important part in the C. fetus contamination of humans.