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Am J Vet Res. 1996 Jan;57(1):39-42.

Epidemiological characteristics of bovine clinical mastitis caused by Staphylococcus aureus and Escherichia coli studied by DNA fingerprinting.

Author information

1
Department of Herd Health and Reproduction, Utrecht University, Netherlands.

Abstract

OBJECTIVE:

To study the epidemiology of clinical mastitis caused by Escherichia coli and Staphylococcus aureus by differentiating isolates with DNA fingerprinting techniques, using polymerase chain reaction.

DESIGN:

Milk samples were collected from cases of clinical mastitis in dairy cows. Escherichia coli and S aureus isolates from these cases were compared within and between cows and herds.

SAMPLE POPULATION:

Seven dairy herds with an average bulk milk somatic cell count < 150,000/ml, and incidence of cows with clinical mastitis of > 25%/y.

PROCEDURE:

Chromosomal DNA was isolated from E coli and S aureus strains isolated from cases of clinical mastitis, and amplified by polymerase chain reaction, using enterobacterial repetitive intergenic consensus primers for E coli and a random amplified polymorphic DNA primer for S aureus. Escherichia coli and S aureus strains were identified and differentiated, using their DNA polymorphism pattern.

RESULTS:

Multiple E coli genotypes were found in each of the herds. Persistent infections with E coli were sporadic. Only a limited number of different S aureus genotypes was found in each of the herds studied. Recurrent cases of S aureus mastitis were found in 25% of quarters with clinical S aureus mastitis. Comparing S aureus isolates from different herds indicated that 1 S aureus genotype was most prevalent.

CONCLUSIONS:

Because different quarters were infected with different genotypes, it was concluded that E coli is an environmental pathogen, and does not generally spread from quarter to quarter. The hypothesis that S aureus mastitis is a contagious disease, spreading from infected to uninfected quarters, could not be rejected.

PMID:
8720235
[Indexed for MEDLINE]

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