Novel biocides as potential antibacterial alternatives for dairy associated pathogens

Background Two diseases of economic and welfare impact in the dairy industry are mastitis and digital dermatitis (infectious lameness). To control and treat these two diseases under field conditions, antibiotics or toxic chemicals are first line treatments. In the current study, we evaluated novel biocides with potential for low environmental or human toxicity for their antimicrobial activity under field-like conditions. Methods Fifteen biocides, including cuminaldehyde guanylhydrazone, and several other guanylhydrazone derivatives, were tested against two Treponema species, a Peptinophilus species, Streptococcus uberis , mastitis-associated E. coli , Pseudomonas aeruginosa , Staphylococcus aureus , Mannheimia haemolytica , Fusobacterium necrophorum , and Porphyromonas levii . Bactericidal concentrations were determined by serial dilution of the biocide, incubation of log phase bacteria with the biocide for 10 min or longer and transfer to fresh growth media. Results Biocide compounds cuminaldehyde guanylhydrazone, related guanylhydrazone derivatives, thymol and ethyl lauroyl arginate were bactericidal in less than 10 min and effective in the presence of manure and milk. Additionally, these biocides demonstrate antibacterial activity in the presence of pre-formed biofilms. Conclusions Given the broad range effectiveness of these biocides, further testing at larger scale and in vivo is needed to further develop these products as alternatives to traditional antibiotics or chemical treatments for use in livestock.