Staphylococcus aureus shedding pattern throughout lactation in dairy cows with naturally occurring intramammary infection.
J Am Vet Med Assoc
; 242(10): 1410-8, 2013 May 15.
Article
en En
| MEDLINE
| ID: mdl-23634687
ABSTRACT
OBJECTIVE:
To evaluate shedding patterns of Staphylococcus aureus, specifically the association between clonal relatedness and shedding patterns of S aureus for cows with naturally occurring S aureus intramammary infection.DESIGN:
Longitudinal field study. SAMPLE Milk samples from 22 lactating cows (29 mammary glands) of varied numbers of lactations on 2 dairies. Procedures-Foremilk samples were collected weekly for 26 to 44 weeks during lactation from individual mammary glands. Milk samples were cultured bacteriologically with a 0.01-mL inoculum. Samples were considered culture positive for S aureus if ≥ 1 colony-forming units were obtained. Milk samples from known S aureus-positive mammary glands that were culture negative for S aureus or culture positive with a single colony of S aureus were cultured bacteriologically a second time with a 0.1-mL inoculum. Longitudinal shedding patterns of S aureus and the effect of strain type on ln(colony forming unit count) were examined.RESULTS:
With the 0.01-mL inoculum, 914 of 1,070 (85%) samples were culture positive. After reculturing of negative samples with a 0.1-mL inoculum, 1,011 (95%) of the samples were culture positive. There was no significant difference in the detection of S aureus between genotypic clusters when either the 0.01- or 0.1-mL inoculum was used. There was no significant difference in the amount of shedding between mammary glands infected with isolates in genotypic cluster 1 or 2. No consistent shedding patterns were identified among or within cows. There was a significant difference in mammary gland linear score and test day (composite) linear score between mammary glands infected with isolates in genotypic clusters 1 and 2. CONCLUSIONS AND CLINICAL RELEVANCE S aureus was shed consistently in cows with naturally occurring intramammary infection in cows, and regardless of the pulsotype, variations in the amount of S aureus shedding had no significant effect on the ability to detect S aureus with a 0.1-mL inoculum.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Infecciones Estafilocócicas
/
Staphylococcus aureus
/
Lactancia
/
Derrame de Bacterias
/
Mastitis Bovina
Tipo de estudio:
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
J Am Vet Med Assoc
Año:
2013
Tipo del documento:
Article
País de afiliación:
Estados Unidos