Bacterial growth in expressed breast-milk

We determined the degree of bacterial contamination and the rate of bacterial growth in expressed breast-milk stored in a tropical environment with high ambient temperatures and humidity. Colostrum or mature milk obtained from mothers who were delivered preterm or at term was stored at room temperature (27-32°C) and in a refrigerator (4°C) over a 24-h period. Bacterial isolates represented normal skin flora. Our study showed that colostrum was more inhibitory than mature milk, and term colostrum more so than preterm colostrum. At room temperature, mature milk from term mothers could be stored for 6 h without a significant increase in bacterial counts. Term colostrum could be stored for 12 h without significant bacterial growth. Preterm milk could be stored for 4 hr. Our findings should be of practical value to lactating mothers without access to refrigerators.