Detection of Mycoplasma bovis in Preservative-Treated Field Milk Samples

¹ Microbiology Research and Development, Hospital Products Division, Abbott Laboratories, Abbott Park, IL 60064
² Veterinary Medical Research Institute, Iowa State University, Ames 50011
³ Federal Institute for Health Protection of Consumers and Veterinary Medicine, Jena, Germany
⁴ Department of Animal Science, Iowa State University, Ames 50011

Control of mycoplasmal mastitis requires individual cow milk sampling for culture and identification of Mycoplasma bovis. This sampling is time-consuming and expensive. Currently, some herds sample cows monthly with the dairy herd improvement (DHI) program, but a preservative is added to this milk that kills M. bovis. In this paper, a nested polymerase chain reaction (PCR) procedure that allows for rapid testing of preservative-treated milk is validated. The specificity of the nested PCR assay was confirmed by testing isolated nucleic acids of other organisms phylogenetically related to M. bovis or common to milk. A comparison against blind-passage culture on 53 field milk samples determined its sensitivity. Exposure of seeded milk samples to the procedure resulted in a sensitivity of 5.1 cfu equivalents per milliliter. Analysis of these results proved that the nested PCR assay was as sensitive as traditional culture and can be used on preservative-treated milk.

Key Words: Mycoplasma bovis • mycoplasma detection • polymerase chain reaction • preservative-treated milk

Submitted on August 11, 2000
Accepted on February 23, 2001