Chicken embryo lethality assay for determining the lethal dose and virulence of Enterococcus faecalis.
Avian Pathol
; 46(5): 548-555, 2017 Oct.
Article
en En
| MEDLINE
| ID: mdl-28470098
ABSTRACT
Enterococcus faecalis is the major pathogen found in field cases of amyloid arthropathy in chickens. Given the need for a better understanding of the virulence mechanisms of the causative strains, the embryo lethality assay (ELA) is proposed in the present study as a model to evaluate the virulence of E. faecalis strains, specifically the pathogenic avian strain K923/96, which was previously related with amyloid arthropathy. Hence, 0.2â
ml of five doses of the cited strain (from 2.5 to 2500 colony-forming units (CFU) per ml) were inoculated into the allantoic cavity of 10-day-old embryos. The embryo mortality rate (EMR) was determined by daily candling of the eggs over a period of seven days and based on this information the median lethal dose (LD50) was calculated. The ELA was repeated four times on a sample of 3443 eggs. The infectious dose showed a significant effect on the EMR. The EMR with the doses of 2.5, 5, 25, 250 and 2500â
CFU/ml was 43%, 45%, 63%, 90% and 93%, respectively. The estimated dose at LD50 was 6.6â
CFU/ml. As expected, the higher the infectious dose, the greater the EMR and the lower the embryo survival time. The highest EMR was recorded after three and four days post-inoculation in all doses. In conclusion, these results can be used as a basis for further researches on the E. faecalis virulence. In order to corroborate its model capacity to predict the virulence of this bacterium, more ELAs with different E. faecalis strains are required.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Enfermedades de las Aves de Corral
/
Embrión de Pollo
/
Infecciones por Bacterias Grampositivas
/
Enterococcus faecalis
Tipo de estudio:
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Avian Pathol
Año:
2017
Tipo del documento:
Article
País de afiliación:
Alemania