Radiometric pooled faecal culture for the detection of Mycobacterium avium subsp paratuberculosis in low-shedder cattle.
Aust Vet J
; 86(7): 259-65, 2008 Jul.
Article
en En
| MEDLINE
| ID: mdl-18616475
ABSTRACT
OBJECTIVE:
To identify the optimum pooling rate for pooled faecal culture (PFC) as a diagnostic tool in bovine Johne's disease control, for detection of cattle shedding low concentrations of Mycobacterium avium subsp paratuberculosis (Map).METHOD:
Thirteen target animals were selected by delayed growth of Map from initial individual radiometric faecal cultures (first growth index at 5 weeks or later). A procedure based on radiometric culture and IS900 polymerase chain reaction and restriction endonuclease analysis confirmation was then used for PFC.RESULTS:
Eight samples (stored for up to 17 months at -80 degrees C) yielded Map on subsequent culture, either from undiluted faeces or those mixed with normal cattle faeces at dilution rates from 1 in 5 to 1 in 50. From a regression equation, culture-positive animals were considered to be shedding relatively low levels of Map (< 6 x 10(4)/g of faeces). Pooling dilutions of more than 1 in 5 reduced PFC sensitivity. A minimum incubation period of 10 weeks at a dilution of 1 in 5 is recommended to detect such infected cattle. This pooling rate in radiometric culture is probably capable of detecting cattle shedding < or = 5 x 10(3) Map organisms/g of faeces, representing an estimated inoculum per culture vial of fewer than 20 viable organisms.CONCLUSION:
Map was detected in more than 50% of the stored faecal samples from cattle shedding low concentrations of the organism. A pooling rate of 5 samples per pool is required to reliably detect infected low-shedder cattle using PFC based on radiometric culture.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Paratuberculosis
/
Radiometría
/
Enfermedades de los Bovinos
/
Mycobacterium avium subsp. paratuberculosis
/
Heces
Tipo de estudio:
Diagnostic_studies
/
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Aust Vet J
Año:
2008
Tipo del documento:
Article