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- Author or Editor: Larry K. Fox x
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Abstract
Objective—To determine patterns of mycoplasma shedding in the milk of dairy cows with intramammary mycoplasma infection.
Design—Prospective clinical trial.
Animals—10 Holstein cows with intramammary mycoplasma infection.
Procedure—Milk samples were collected from each cow daily for 28 days and plated on mycoplasma agar to evaluate shedding patterns. To determine whether enrichment improved recovery of organisms, some samples were also inoculated in mycoplasma enrichment medium and incubated for 4 days prior to plating. Somatic cell count (SCC) was determined in samples collected weekly.
Results—Mycoplasma organisms were not isolated from 81 of 280 (29%) composite milk samples, but > 106 colonies/mL were obtained from 151 (54%). Similarly, mycoplasma organisms were not isolated from 433 of 1,008 (43%) quarter milk samples, but > 106 colonies/mL were obtained from 392 (39%). For 71 of 104 (68%) samples, mycoplasma organisms were isolated both following direct plating and following enrichment; for 24 of 104 (23%), mycoplasma organisms were isolated only following enrichment; and for 9 of 104 (9%), mycoplasma organisms were isolated only after direct plating. There was a linear correlation between logarithm of the SCC and logarithm of the number of colony-forming units of mycoplasma per milliliter of milk for composite and quarter milk samples.
Conclusions and Clinical Relevance—Shedding of organisms was inconsistent in dairy cows with intramammary mycoplasma infection, increasing the risk of misdiagnosis if multiple milk samples are not tested. (J Am Vet Med Assoc 2003;223:1163–1166).
Abstract
Objective—To determine the epidemiologic pattern of intramammary infections (IMIs) with Staphylococcus aureus during implementation of a control program in 9 commercial dairy herds.
Design—Cohort study.
Animals—1,651 lactating cows and 53,098 quarter milk samples.
Procedures—Nine herds located in different regions of Italy were enrolled. Control of S aureus infections followed the general principles of contagious mastitis control and was based on precise diagnostic procedures and strict control and segregation of infected cows. All lactating cows in each herd were tested, and those free of S aureus IMI were enrolled as the cohorts. Further additions to the cohort group were cows and heifers free of S aureus IMI, as determined from aseptically collected milk samples taken approximately 7 and 14 days after calving.
Results—After the ninth month of the program, incidence decreased to < 2 new IMIs/100 cow-months in 7 of the herds. At the end of the study, 8 of 9 herds had an incidence of ≤ 1 new IMI/100 cow-months. Heifers were most at risk of developing an IMI.
Conclusions and Clinical Relevance—Results suggest that control of S aureus IMIs can be achieved by use of a control program based on segregation and use of hygienic and therapeutic protocols. Analysis of incidence and identification of risk factors in a herd could avoid the possible shortcomings of the program, maximizing the probability of success. (J Am Vet Med Assoc 2003;223:684–688)
Abstract
Objective—To determine whether Mycoplasma strains typically associated with mastitis in dairy cattle can be isolated from body sites other than the mammary gland.
Design—Prospective clinical trial.
Animals—7 Holstein cows in various stages of lactation with intramammary Mycoplasma infection.
Procedure—Milk samples, antemortem swab specimens from various body sites, and postmortem swab and tissue specimens were submitted for Mycoplasma culture. Pulsed-field gel electrophoresis (PFGE) was performed on chromosomal digests of all Mycoplasma isolates. Isolates with the same number and size of chromosomal digest bands were considered to be of the same type.
Results—For each cow, all isolates obtained from milk, mammary gland parenchyma, and supramammary lymph nodes had the same PFGE pattern. All cows had at least 1 isolate from nonmammary system tissues that had the same PFGE pattern as isolates from the mammary system. Overall, 44 of the 70 (63%) Mycoplasma isolates obtained from body sites other than mammary system sites had the same PFGE pattern as did mammary system isolates.
Conclusions and Clinical Relevance—Results confirmed our hypothesis that Mycoplasma strains isolated from the milk of dairy cattle with Mycoplasma mastitis frequently have PFGE patterns identical to those for strains isolated from other body sites, suggesting that there is at least a potential for internal transmission of Mycoplasma organisms. (J Am Vet Med Assoc 2005;227:455–459)
