Antibacterial activity of bovine lactoferrin hydrolysate against mastitis pathogens and its effect on superoxide production of bovine neutrophils.

Antibacterial activity of bovine lactoferrin hydrolysates (LFH) on microorganisms isolated from bovine mastitis, and superoxide (O(2)(-)) production of bovine neutrophils were evaluated. Antibacterial effects of LFH were measured in vitro against Staphylococcus aureus, coagulase-negative staphylococci, Streptococci, Enterococci, Escherichia coli, Klebsiella pneumoniae, yeast-like fungi and Prototheca zopfii isolated from clinical cases of bovine mastitis. To compare susceptibilities against LFH, minimal inhibitory concentration (MIC) values were determined by a micro-plate assay method. Most organisms were sensitive to LFH. Prototheca zopfii was highly sensitive to LFH; the growth of the microorganism was inhibited completely even at 1 mug/ml. Staphylococcus aureus and Escherichia coli were resistant to LFH. The production of O(2)(-) by bovine neutrophils was used to evaluate the effect of LFH administration on functional activity. Increase in O(2)(-) production by bovine neutrophils occurred upon addition of LFH to neutrophils. These results demonstrate that LFH possesses antibacterial activity against pathogens that cause mastitis and activates neutrophil superoxide production.