American journal of veterinary research · 1996
Epidemiological characteristics of bovine clinical mastitis caused by Staphylococcus aureus and Escherichia coli studied by DNA fingerprinting.
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Lam T J, Lipman L J, Schukken Y H, Gaastra W, Brand A
Аннотация
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.
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.