Abstract
Recent recommendations have discouraged the use of frozen human breast milk for the feeding of preterm or sick newborns, based on animal model data which demonstrated a failure of frozen rat milk to inhibit bacterial growth in vitro or prevent bacterial induced necrotizing enterocolitis in vivo. Nine human breast milk samples were collected and aliquots were maintained at room temperature, frozen, and pasteurized. Samples were inoculated with 10-50 colony forming units per ml (CFU/ml) of E. coli (K1) or group B streptococcus (la) and incubated at 37°C. Quantitative growth was measured at eight and 24 hours. Control broth, commercial formula, and pasteurized breast milk showed no inhibition with a rapid logarithmic growth to a maximum of 108 - 109 CFU/ml at 24 hours. Compared to these controls, fresh breast milk, fresh frozen breast milk, and that frozen for 21 days demonstrated significant inhibition of growth (p < 0.001). A trend toward loss of inhibiting activity for group B streptococcus was noted with prolonged freezing of breast milk but not for E. coli. The bacterial growth inhibiting effect of human breast milk may be multifactorial (cells, antibodies, complement, lactoferrin, lysozyme). Although freezing may quantitatively decrease the amount of some of these factors, it cannot be assumed that comparable functional reductions will necessarily result.
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Hernandez, J., Lemons, P., Lemons, J. et al. 977 EFFECT OF PASTEURIZATION AND FREEZING M THE BACTERIAL GROWTH INHIBITING ACTIVITY OF HUMAN BREAST MILK. Pediatr Res 12 (Suppl 4), 526 (1978). https://doi.org/10.1203/00006450-197804001-00983
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DOI: https://doi.org/10.1203/00006450-197804001-00983
