Date of Award:

5-2010

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Animal, Dairy, and Veterinary Sciences

Committee Chair(s)

David Wilson

Committee

David Wilson

Committee

Brian Gowen

Committee

Kerry Rood

Committee

Ken White

Abstract

Mycoplasmas are a group of bacteria which are small in size, lack a cell wall, and have small genomes in comparison to other bacteria. The members of the group that are pathogenic utilize several mechanisms to evade the host's immune system. These processes affect surveillance and control mechanisms such as serologic testing and vaccination. Many of these organisms cause diseases of livestock, which heavily impact production parameters such as weight gain, milk yield, and egg production. Mycoplasmas also cause disease in people.

Mycoplasma spp. can cause mastitis, metritis, pneumonia, and arthritis. The currently documented routes of transmission of Mycoplasma spp. are through fomites and by direct animal contact. The existence of environmental sources for Mycoplasma spp. and their role in transmission are poorly characterized. Mycoplasma spp. (confirmed as M. bovis using PCR) was found in recycled bedding sand from a dairy experiencing an outbreak of mycoplasma mastitis. The possibility of a persistent environmental source of Mycoplasma spp. in recycled bedding sand was further investigated using recycled sand from the dairy. Study objectives included determining factors associated with the persistence of Mycoplasma spp. in recycled bedding sand and the duration of survival of mycoplasmas in the sand. We also evaluated 2 disinfectants at 2 different concentrations each for the elimination of Mycoplasma spp. from contaminated sand.

Mycoplasma spp. survived in the sand pile intermittently over a period of 8 months. The concentration of Mycoplasma spp. within the sand pile was directly related to temperature and precipitation. The survival of Mycoplasma spp. at a greater than expected range of temperatures suggests the formation of a biofilm. Ideal temperatures for replication of Mycoplasma spp. occurred between 15 °C and 20 °C. Moisture in the sand and movement of the sand pile also appeared to play a role in replication of mycoplasmas. Sodium hypochlorite (0.5%) and chlorhexidine (2%) were efficacious in eliminating Mycoplasma spp. from contaminated bedding sand. Recycled bedding sand could be an environmental source of Mycoplasma spp. infections, including M. bovis, in dairy cows. Future studies should investigate the contribution of this environmental source to the epidemiology of mycoplasma infections in dairy cattle and other ruminants.

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This work made publicly available electronically on August 30, 2010.

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