Biomedical subjects

C T Hutton

Publications and source records attributed to C T Hutton.

3 recordsLinked to original sources

PubMed1992

Comparison of media to isolate Staphylococcus aureus from teat skin and milking unit liners.

Four procedures were compared for isolation of Staphylococcus aureus from swabbing solutions of teat skin and milking unit liners from commercial dairies. In 2 procedures, 0.1 ml of swabbing solutions were added to either 5 ml Vogel-Johnson or Baird Parker broth media and enriched at 37 degrees C, 4 h. Following enrichment, 0.1 ml culture was transferred to modified Baird-Parker agar and incubated at 37 degrees C, 48 h. In the other 2 procedures, 0.1 ml of swabbing solution was directly placed on either blood or modified Baird-Parker agar plates and incubated at 37 degrees C 48 h. Combining results from all methods, Staphylococcus aureus were isolated from 72 of 913 (7.9%) skin samples, and 34 of 268 liners (12.6%). On average, 43.1% (31/72) of the S. aureus isolates were found by the enrichment in liquid Vogel-Johnson procedure. The average isolation percentage for other methods ranged from 19.4% to 25.0%. Isolation of S. aureus from milking unit liner or teat skin swabbing solutions was approximately twice as likely after enrichment in Vogel-Johnson liquid media as opposed to other methods of isolation. This indicates that enrichment in Vogel-Johnson liquid media improved recovery of S. aureus from swabbing solutions.

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PubMed1991

Fomites and reservoirs of Staphylococcus aureus causing intramammary infections as determined by phage typing: the effect of milking time hygiene practices.

We studied the association of milkers' hands and milking unit liners as fomites, and teat skin as a reservoir, with S. aureus intramammary infections (IMI). Samples were collected from 40 commercial herds and S. aureus isolates were phage typed. Only 10 of 257 isolates were not typable. Of the milk samples, 8.4% had typable S. aureus; 4.5% and 9.2% of the skin and liner swabbings had typable S. aureus. Twenty-three different phage types were identified, 1 type was found in nearly 75% of the herds. Herds in which milking unit backflush was used were less likely to have the same phage type on the liners and the teat skin, and on the liners and milk samples, than herds that did not backflush. A greater percentage of liners had S. aureus of the same type as those causing S. aureus IMI, than skin swabbing solutions with the same type as that associated with IMI. Herds which did not use post-milking teat asepsis (teat dip) did not have a greater percentage of S. aureus isolates on the teat skin, nor were the S. aureus test skin isolates more likely to be of the same type as those causing intramammary infection. Results would suggest that the liner appears to be a significant fomite, that backflushing reduces its significance, and that teat skin is a less significant reservoir for S. aureus intramammary infection.

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PubMed1990

Mastitis control practices: differences between herds with high and low milk somatic cell counts.

Effects of differences in herd mastitis control management in maintaining low herd average SCC, was studied. Washington State DHI herds with Holstein cattle and enrolled in the SCC program (n = 309) were ranked by percentage of cows in their herd with SCC less less than or equal to 283,000 cells/ml. "Low herds" (n = 28) were among the 56 herds with the highest percentage of cows with SCC less than or equal to 283,000 cells/ml and "high herds" (n = 31) were among the 75 with the lowest percentage of cows with SCC less than or equal to 283,000 cells/ml. Herds were visited annually for 2 yr by a technician who collected samples and recorded data. Geometric mean bulk tank SCC during the year between herd visits was 175,000 and 460,000 cells/ml for low and high herds. Milking time hygiene practices, teat dipping, and dry cow therapy were practiced with equal frequency on low and high herds. Differences in function and maintenance of milking equipment did not discriminate between herd groups. Differences in mastitis control management of low versus high SCC herds were that managers of excellent control herds more frequently had highest producers milked first and clinical cows milked last; had automatic milking unit detachers; kept moisture content of cow bedding lower; and had workers disinfect teat ends prior to intramammary antibiotic treatment. Managers of low herds were more likely to use computers and attend dairy informational meetings. Results suggest subtle differences in mastitis control strategies differentiate the low and high SCC herd groups.

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