Human Milk Antibacterial Factors
Bovine milk will eventually spoil at refrigeration temperatures, but endogenous or exogenous pathogenic or spoilage bacteria in human milk stored for delayed feeding will die. We investigated the mechanism for these antibacterial properties and their response to high-tempertature, short-time (HTST, 72°C-75°C, 15 sec) and low-temperature long-time (LTLT, 65°C, 30min) pasteurization. NonpathogenicListeria innocua(106cfu/mL) was inoculated into raw and processed bovine and human milk; bacterial plate counts twice weekly determined antibacterial activities. Up to 99% ofL. innocuawere killed and further growth was inhibited in raw and pasteurized human milk for at least 60 days at 4°C. Reactive IgA antibodies againstListeriaantigens were demonstrated by enzyme immunoassay in some human milk samples; sIgA activity againstEscherichia coliO antigens was significantly decreased by heat treatments (raw, 1.8; HTST, 1.1; LTLT, 1.3 activity units). Adding human lactoferrin (0.5-20 mg/mL) to theListeriainoculum (-107cfu/mL) in 1% peptone water did not inhibit bacterial growth.
KeywordsMilk Sample Human Milk Bovine Milk Peptone Water Refrigeration Temperature
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