Immune and experimental infection responses of dairy cows vaccinated with the combination of six Staphylococcus aureus proteins that are expressed during bovine intramammary infection and a triple adjuvant

Abstract Purpose Staphylococcus aureus (S. aureus) is the most important pathogen involved in bovine mastitis in dairy production. S. aureus produces a spectrum of extracellular protein toxins and virulence factors which are thought to contribute to the pathogenicity of the organism. The aim of this work was to isolate and molecular characterize S. aureus associated with bovine subclinical mastitis in the central part of Ethiopia. Methods A total of 265 lactating dairy cows from various dairy farms in four different geographical locations were screened by the California mastitis test (CMT) for bovine subclinical mastitis. One hundred thirty CMT-positive milk samples were collected and transported to the laboratory. Different biochemical tests and polymerase chain reaction (PCR) were used for the identification of S. aureus isolates. Finally, PCR was performed for molecular detection of virulence genes. Results From a total of 265 lactating dairy cows screened, 49% (n = 130) were positive for bovine subclinical mastitis. One hundred thirty mastitic milk samples were subjected to bacterial culturing, and one hundred (76%) S. aureus isolates were identified based on phenotypic characters. Sixty-eight confirmed S. aureus isolates were obtained using PCR. The confirmed S. aureus isolates were tested for six virulence genes (tsst-1, hlb, eta, sea, clfA, and icaD) using PCR. Of the six virulence genes screened from all the isolates, only two (clfA and eta) were detected in the isolates. Out of 68 isolates, 25% and 22% were possessed the eta and clfA genes, respectively. Conclusion The presence of Staphylococcus aureus having virulence genes (eta and clfA) revealed that mastitis is a major concern nowadays affecting animal health, milk quality, and yield. Further genomic study of these isolates will provide broad new insights on virulence.

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The effect of inoculating the bovine teat duct with small numbers of Staphylococcus aureus

Journal of Dairy Research ◽

10.1017/s0022029900018501 ◽

1965 ◽

Vol 32 (2) ◽

pp. 171-179 ◽

Cited By ~ 25

Author(s):

F. H. S. Newbould ◽

F. K. Neave

Keyword(s):

Staphylococcus Aureus ◽

Stainless Steel ◽

Post Inoculation ◽

Intramammary Infection ◽

Colony Forming Units ◽

Previous Infection ◽

Glass Rods

SummaryFifty-seven inoculations of a strain of Staphylococcus aureus were made into the outer 4 mm of the teat ducts of 8 cows. The inocula ranged from 10 to 600 colony-forming units (CFU) and were made with a stainless steel instrument designed to overcome the disadvantages of glass rods and cotton swabs hitherto used.A single inoculation resulted in either no colonization of the duct, in temporary colonization for up to 7 days, or in colonization followed by intramammary infection.The recovery of the organisms depended on the size of the inoculum. When 70–100 CFU were placed in the teat duct no organisms were recovered from 12 of 24 quarters after the 1st post-inoculation milking. When 500–600 CFU were used, organisms were recovered from all of 31 quarters for at least 3 milkings, and from 61% for 6 milkings or more, in spite of dipping the teats in a strong disinfectant twice daily.Intramammary infection developed in 1 of 12 quarters (8%) inoculated in the teat duct with about 600 CFU when the animals were milked twice daily, and in 5 of 19 (23%) quarters if the 1st post-inoculation milking was omitted.There was no evidence of sensitization resulting from previous infection.

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