OxyFile #344

Bactericidal Effects of Ozone at Nonspermicidal Concentrations

C. Gradil, M.D. Eaglesome, B. Stewart, M.M. Garcia, and F. Quimby

Canadian Journal of Veterinarian Research 1995; 59: 183-186

ABSTRACT

A study was conducted to assess the use of ozone (O3) to control 
pathogens or contaminants of concern to animal breeders and 
regulatory officials. In separate experiments, samples of fresh 
bovine semen and Pseudomonas aeruginosa, Escherichia coli, or 
Camplylobacter fetus subsp. veneralis were diluted with 
antibiotic-free milk (10 ^6 sperm and 10 ^6 organisms/mL of 
diluted semen), exposed in the previous day to a constantly 
monitored level of 5,10,15 or 20 ug.\mL of O3 for 3-5 min. After 
10 min at 30 degrees C, sperm motility was assessed and the 
samples cooled to 5 degrees C. Two and 18 h after the beginning of 
cooling, aliquots of each semen sample were evaluated for motility 
and cultured for organisms. Reductions were observed in P. 
aeruginosa and E. coli colony counts of 2 logs, and in C. fetus of 
5 logs, after exposure for 2 h to O3 at a concentration of 5ug/mL 
that had a moderate effect on sperm motility (reduction of 20%). 
Fewer than 100 colonies, i.e., a 4 logs reduction of all bacteria, 
were counted after dilution with ozonized-treated milk at 20 ug/mL 
of O3. However, this concentration of O3 reduced sperm motility by 
50% 10 min after dilution. The results of these experiments 
indicate that a concentration and exposure time to O3 can be 
selected to reduce P. aeruginosa, E. coli, and C. fetus in 
contaminated bull semen diluted with milk while having only 
minimal effects on sperm motility.