The bacteriocin nisin, an effective agent for the treatment of staphylococcal mastitis during lactation.

Eight women with clinical signs of staphylococcal mastitis were randomly divided in 2 groups. A solution of the bacteriocin nisin (6 microg/mL) was applied to the nipple and mammary areola of those assigned to the nisin group for 2 weeks, and a similar preparation devoid of nisin was applied to the control group. On day 0, staphylococcal counts in breast milk of the nisin and control groups were similar (5.04+/-0.19 and 4.88+/-0.21 log10 CFU/mL, respectively). However, on day 14, the mean in the nisin group (3.22+/-0.43 log10 CFU/mL) was statistically lower than that of the control group (5.01+/-0.21 log10 CFU/mL). No clinical signs of mastitis were observed among the women of the nisin group on day 14, whereas they persisted throughout the study in the women of the control group. In conclusion, nisin seems to be an efficient alternative to antibiotics for the treatment of staphylococcal mastitis.