Effects of human milk fortifier with iron on the bacteriostatic properties of breast milk.

OBJECTIVE To compare bacterial growth in pure colostrum versus colostrum with human milk fortifier (HMF) containing iron. METHODS The growth of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa in 78 samples of pure colostrum or colostrum with added iron-containing HMF was compared. For qualitative analysis, filter paper discs were immersed in samples from each group and incubated for 48 hours with 10(1) colony forming units (CFUs)/mL of each strain. For quantitative assessment, 1 mL of each strain containing 10(7) CFUs/mL was homogenized with 1 mL of either colostrum or colostrum with human milk fortifier, seeded into a Petri dish, and incubated at 37°C. Twenty-four hours later, the number of CFUs was counted. RESULTS The qualitative analysis showed no difference in bacterial growth. In the quantitative evaluation, E. coli growth in the control group was 29.4±9.7×10(6)CFU/mL, while in the HMF group it was 31.2±10.8×10(6)CFU/mL. The difference between the average growth was 1.9±4.9×10(6)CFU/mL (p=0.001). There were no differences in S. aureus and P. aeruginosa growth. CONCLUSION Addition of iron at this concentration reduces breast milk bacteriostatic action against E. coli.