Author(s): Cao LT, Wu JQ, Xie F, Hu SH, Mo Y
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Abstract Nisin is an antimicrobial polypeptide produced by Lactococcus lactis and is believed nontoxic to humans. The objective of this study was to evaluate a nisin-based formulation for the treatment of bovine clinical mastitis in lactating dairy cattle. A total of 92 cows with 107 clinically mastitic quarters were randomly assigned to nisin- (48 cows with 51 quarters) and gentamicin (GM)-treated (44 cows with 56 quarters) groups. In the nisin-treated group, cows received an intramammary infusion of nisin at a dose of 2,500,000 IU; in the GM-treated group, intramammary infusion of GM was administered at a dose of 0.8 g. Results indicated that nisin offered a clinical cure rate similar to GM (90.2 vs. 91.1\%) and no difference in bacteriological cure rate than GM-treated group (60.8 vs. 44.6\%, respectively). Proportion of the quarters with milk somatic cell counts <500,000 cells/mL was not different in the nisin-treated group (50.0 and 47.8\%) compared with the GM-treated group (33.3 and 37.3\%) 1 and 2 wk after treatment. Of 17 Staphylococcus aureus isolates, 82.5\% were resistant to penicillin, and 35.3\% to GM, but none of them to nisin. Nisin therapy eliminated 54.5\% (6 of 11) of S. aureus IMI, whereas GM eliminated 33.3\% (2 of 6). Nisin in milk (4.5 +/- 0.8 IU/mL) was detected only at 12 h following intramammary infusion, which was much lower than the upper limit (500 mg/mL) allowed as preservative in milk by the China authority. Because of its efficacy in the treatment of bovine clinical mastitis, especially resistant Staph. aureus-caused IMI, as well as its safety in humans, nisin deserves further study to clarify its effects on mastitis caused by different mastitis pathogens on a larger scale.
This article was published in J Dairy Sci
and referenced in Advances in Dairy Research