Effects of Temperature and Humidity on the Survival of Mycoplasma Organisms in Recycled Bedding Sand

Abstract

Mycoplasma bovis, along with other species, is responsible for a number of disease syndromes in cattle which impact both the dairy and beef industries. An outbreak of mycoplasma mastitis in conjunction with a number of positive environmental samples from the farm initiated a study of the survival of mycoplasma organisms in recycled bedding sand. A pile of bedding sand was obtained from the affected dairy and brought to Utah State University, where it was stored outside. The pile was cultured for mycoplasmas and mastitis pathogens on a weekly basis for four months, and then sampled every two to four weeks for another four months. In addition, samples of the sand were subjected to controlled experiments in the laboratory involving temperature, humidity, and chemical disinfection. The results indicate that M. bovis can remain viable and detectable by culture in recycled bedding sand for eight months at the ambient temperatures found in Logan, Utah. The optimal temperature for survival is between 39°F (4°C) and 64°F (18°C). The numbers of M. bovis organisms (measured as colony forming units) in the sand increased at different times during the study, indicating replication. M. bovis reproduced in bedding sand at ambient maximum temperatures between 59°F and 68°F (15°C and 20°C). In the controlled experiment, mycoplasmas reproduced in the bedding sand at 97°F (36°C) when the sand was kept damp, but were not cultivable when it was allowed to dry out. Both 2% chlorhexidine and 0.5% hypochlorite were capable of disinfecting the bedding sand.