Alternative Methods of Evaluation of Antimicrobial Activity of Breast Milk Serum.

Antimicrobial properties are traditionally evaluated by the seeding technique, which is laborious, time-consuming, and rather imprecise. We studied the possibility of using microscopy and spectrophotometry methods for evaluation of cytotoxic activity of breast milk serum against opportunistic microbes. Activity of 50 breast milk samples obtained from healthy women at different lactation stages was tested against opportunistic yeast C. albicans. Microscopy showed that incubation of cell suspension with lactoserum led to destruction of cell walls and cytoplasmic membranes with the formation of vesicular debris that absorbed the dye from the medium. Spectrophotometric measurement of the dye remained in the medium revealed a dose-depended effect of the lactoserum on C. albicans cells and strong inverse correlation between the lactation period and cytotoxic activity of the lactoserum (r=-0.948). These methods can be used in veterinary and food processing for estimation of biological activity of milk.